Small bowel length in RYGB: Does limb length matter? Questions remain; Adapting the biliopancreatic and alimentary limb lengths to the total small bowel length in RYGB leads to better postoperative outcomes, such as quality of life, satisfaction with body weight, resolution of comorbidities and iron deficiency

Small bowel length in RYGB: Does limb length matter? Questions remain; Adapting the biliopancreatic and alimentary limb lengths to the total small bowel length in RYGB leads to better postoperative outcomes, such as quality of life, satisfaction with body weight, resolution of comorbidities and iron deficiency | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Small bowel length in RYGB: Does limb length matter? Questions remain; Adapting the biliopancreatic and alimentary limb lengths to the total small bowel length in RYGB leads to better postoperative outcomes, such as quality of life, satisfaction with body weight, resolution of comorbidities and iron deficiency Luise Eva Köhler, Ulrich Stefenelli, Resa Puffert, Ioana Andreea Bollenbach, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8464981/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 13 You are reading this latest preprint version Abstract Objective: Roux-en-Y gastric bypass (RYGB) does not account for individual variations in total small bowel length (SBL), which may contribute to variability in outcomes. This study aimed to determine whether postoperative outcomes differ between patients undergoing RYGB with equal BPL and AL lengths, adjusted to the total SBL, resulting in a proportional CC length (NS-RYGB), and patients undergoing standard RYGB (S-RYGB). Methods: In July 2021, our institution switched from performing S-RYGB to new standard RYGB technique (NS-RYGB). In NS-RYGB, the total SBL was measured intraoperatively and equal BPL and AL lenghts were selected, depending on the total SBL, resulting in a proportional CC length. We retrospectively analyzed preoperative and one-year postoperative data from 242 patients, including BMI, resolution of comorbidities, quality of life (QoL), satisfaction with body weight and postoperative iron deficiency. Results: QoL and satisfaction with body weight were significantly higher in the NS-RYGB group one year after surgery. Resolution of arterial hypertension (aHT) and Type-II-diabetes mellitus (T2DM) occured in a significantly greater percentage of NS-RYGB patients. Grade II and III iron deficiency, postoperative complications and hospital readmissions were significantly less frequently in the NS-RYGB group. Mean postoperative weight loss was comparable between the groups. Conclusion: NS-RYGB results in better QoL, higher resolution of aHT and T2DM, greater satisfaction with body weight and less iron deficiency, while achieving similar weight loss. These findings support proportional limb length selection as a promising approach. Further long-term studies are needed to confirm these clinical benefits. Introduction Laparoscopic Roux-en-Y gastric bypass (RYGB) is the most common surgical procedure for treatment of morbid obesity. According to the IFSO Worldwide Survey, 604,099 bariatric procedures, of which 159,543 Roux-en-Y gastric bypass (RYGB) procedures were performed in 2021 [ 1 ]. RYGB results in significant weight loss, i.e. a decrease in BMI of approximately 15 points and 60–70% sustainable excess weight loss (EWL) [ 2 , 7 , 17 – 19 ]. In the western world, RYGB is considered the gold standard of metabolic and bariatric surgery (MBS). Despite its efficacy, RYGB shows considerable interindividual variability in metabolic outcomes [ 4 , 14 , 20 – 21 ]. Furthermore, nutritional deficiencies, particularly iron deficiency, remains common [ 6 , 10 , 23 ]. These inconsistencies may be related to the use of fixed limb lengths that do not consider variations in SBL [ 7 , 9 ]. Therefore, selecting equal lengths for BPL and AL, taking the SBL into account, and resulting in a proportional adjustet CC length, may improve metabolic and nutritional outcomes. In contrast to earlier assumption, RYGB does not merely prevent the absorption of nutrients and decrease the digestion time. Studies have shown that RYGB leads to weight loss through complex metabolic changes, including increases in the serum concentrations of bile acids and increases in the supply of nutrients and bile acids to the ileum [ 5 , 20 – 23 ]. Furthermore, the secretion of incretins following the ingestion of nutrients, especially glucagon-like peptide-1 (GLP-1), is significantly enhanced after RYGB. This is caused by the accelerated transport of nutritional elements from the gastric pouch to the distal ileum [ 5 ]. The selection of limb lengths in RYGB may affect weight loss outcomes and the occurrence of nutritional deficiencies or comorbidities [ 3 ]. In a recent review, Dietrich et al described significant variations in the SBL among individuals and recommended that the length of the CC should not be less than 200 cm. Additionally, they recommended to measure the total SBL prior to RYGB [ 7 ] to avoid malnutrition. A small number of patients seem to have a very short total SBL. Tacchino et al. measured the total SBL of 443 individuals and reported that it was 800 cm in 20% of the individuals [ 9 ]. In contrast, it may be assumed that patients with a SBL > 800 cm could benefit from a longer BLP and AL length, as the use of fixed limb lengths result in a proportionally longer CC, which reduces malabsorbtion and metabolic effects and may contributes to weight loss failure, as 30% of patients experience gastric bypass failure, defined as a percentage of EWL less than 50% [ 9 , 11 , 12 , 14 ]. Another multicenter US cohort study revealed that the CC length is highly variable between individuals [ 8 ]. Most surgeons performing RYGB measure the length of the AL and BPL but not that of the CC because measuring the length of the CC can lead to a longer operation time or small bowel injury [ 3 ]. Early research focused on the impact of the AL length on RYGB outcomes. Historically, the primary aim of the Roux-Y procedure was to prevent bile reflux. Thus, randomized controlled trials (RCTs) have focused on the AL length. However, evidence suggests that lengthening the AL does not provide a weight loss benefit in patients with a BMI < 50 kg/m^2 [ 16 ]. Furthermore, few studies have investigated the influence of the BPL length on weight loss, quality of life (QoL) and comorbidities, especially in the long term. For instance, Homan et al found a significant higher %EWL for the first postoperative years, but no difference in long-term %TWL when lengthening the BPL to 150 cm, compared with standard RYGB [ 4 ]. In contrast, Mahawar et al and Gislasson et al demonstrated that choosing a longer BPL length appears to have a more beneficial effect on weight and comorbidities than choosing a longer AL length does [ 12 , 13 ]. Felsenreich et al suggested that if the BPL length is longer than 150 cm, the total SBL should be measured to ensure a sufficient CC length. Furthermore, at least 300 cm of the small bowel (the CC and AL) should remain in the food stream to prevent deficiencies and malnutrition [ 14 ]. A systematic review by Stefanidis et al. revealed that the extent of malabsorption after gastric bypass is influenced mainly by the length of the CC rather than the length of the AL or BPL. Furthermore, they reported that a longer AL and BPL lead to a shorter CC, which may contribute to malnutrition [ 15 ]. Currently, there is no scientific consensus regarding the optimal BPL or alimentary limb (AL) length relative to the SBL in RYGB. Moreover, although the S3 guidelines of the AWMF suggest a BPL length of 50–80 cm and an AL length of 150–200 cm [ 6 ], there are currently no recommendations regarding the length of the common channel (CC). It is well known that the selection of BPL and AL lengths directly determine the length of the CC. In individuals with a very short total SBL, there is a risk of creating a very short CC during RYGB, which increases the risk of malnutrition, particularly leading to anemia and iron and vitamin B12 deficiency [ 10 ]. In consequence of not defining a clear consensus about the optimal lengths for BPL and AL there is no standardized recommendation on the CC length. Current guidelines, such as the AWMF guideline, provide general recommendations, but do not define an ideal configuration for the selection of limb length [ 6 ]. This lack of evidence represents a substantial knowledge gap addressed in the present study. In this study, we aimed to determine whether postoperative outcomes differ between patients undergoing RYGB in which equal BPL and AL lengths are selected based on the total SBL, resulting into a proportional CC length, and patients undergoing standard RYGB, in which the total SBL is not measured. Considering these findings and the absence of standardized recommendations regarding limb length, we switched from performing standard RYGB (S-RYGB) to new standard RYGB (NS-RYGB) at our institution in July 2021, which represents a complete novel method at our institution. For NS-RYGB, we measured the total SBL intraoperatively and selected equal lengths for the BPL and AL depending on the total SBL. Patient records and follow-up examination data were retrospectively analyzed to determine whether postoperative outcomes differ between patients undergoing RYGP in which equal BPL and AL lengths are selected based on the total SBL and patients undergoing S-RYGP in which the total SBL is not measured. The primary endpoints were the change in body mass index (BMI) and the change in health-related QoL from before surgery to the one-year follow-up. Secondary endpoints included changes in obesity-related comorbidities, patient satisfaction with body weight, iron deficiency incidence, and procedure-related complications before surgery and at the 1-year follow-up. This approach represents a new concept that may reduce variability in postoperative outcomes after RYGB and contributes to a clearer consensus on the optimal limb length. Methods In this study, data that were prospectively collected for patients who underwent MBS at the Obesity Center of Herzogin Elisabeth Hospital in Braunschweig, Germany were retrospectively analyzed. A total of 242 patients were included. The clinical data were prospectively documented in the Quality Assurance Registry of the German Society for General and Visceral Surgery (StuDoQ, DGAV). This study was performed in accordance with the Declaration of Helsinki. Patient selection/Study population Patients were selected and managed by a multidisciplinary team, consisting of bariatic surgeons and clinical nutritionists. Patients with a BMI > 40 kg/m² or a BMI > 35 kg/m² and obesity-related comorbidities, in accordance with the interdisciplinary European guidelines on severe obesity [ 6 ], were included in this study. Exclusion criteria contain refusal of informed consent, incomplete or missing follow-up data, language barrier or severe comorbidities, for e.g. renal diseases (GFS < 30 mL/min), indicating a contraindication for bariatric surgery. All patients were informed about the details of the procedure, benefits and potential risks and were asked if they participate to studies. All patients provided written informed consent to officially confirm participation in the study. Ethical approval was not needed for this retrospective study, as only preexisting, deidentified data from the Quality Assurance Registry of the German Society for General and Visceral Surgery (StuDoQ, DGAV) database were analyzed. Data collection The dataset consisted of patient demographics (age, sex, and BMI), operative details (duration of surgery, CC, BPL, and AL length in cm and total SBL length in cm), and information on the incidence of obesity-associated comorbidities such as arterial hypertension (aHT), type 2 diabetes mellitus (T2DM), obstructive sleep apnea syndrome (OSAS), and gastroesophageal reflux disease (GERD). Additional parameters included iron deficiency, as a type of malnutrition; postoperative complications within one year; QoL and satisfaction with body weight. Data were obtained preoperatively, at 1 year post-operatively and annually thereafter. The procedures were performed by the same surgical team, led by PD Dr. med. habil H. Köhler. Patient groups In this study, two groups were compared. The first group consisted of 113 patients who underwent RYGB in which standard limb lengths were chosen for the BPL and AL, such as a BPL length of 50–80 cm and an AL length of 150–200 cm, following the S3 guidelines of the AWMF [ 6 ] (S-RYGB), from 07/2019 until 11/2020. As we switched from performing S-RYGB to NS-RYGB at our institution in 07/2021, the second group consisted of 129 patients who underwent RYGB in which the total SBL was measured, and equal lengths were selected for the BPL and AL based on the SBL, resulting into a proportional CC length, between 07/2021 and 05/2022. Until today, no identical surgical approach has been described in the literature, thus our method is novel. Surgical Procedure RYGB was performed laparoscopically in an antecolic and antegastric manner in all patients. A small gastric pouch of 40–50 mL was constructed using a 60-mm linear stapler with a blue cartridge (Echelon, Ethicon, Johnson & Johnson, New Brunswick, NJ, USA). The small bowel was measured using a marked grasper. For S-RYGB, the small bowel was separated 80 cm below the ligament of Treitz, a gastroenterostomy was created, and an AL length of 150 cm was selected. For NS-RYGB, the whole bowel was measured from the ligament of Treitz to the ileocecal valve; the small bowel was separated (70–150 cm) below the ligament of Treitz depending on the total SBL; and the selected AL length was the same as the selected BPL length. In both procedures, anastomosis was performed in the same manner. For patients with an SBL 280 cm, and BPL and AL lengths of 100–120 cm was selected. For patients with an SBL > 700 cm, a CC length of > 360 cm and BPL and AL lengths of ≥ 120 cm was selected. Gastrojejunostomy was performed by inserting a 60-mm linear stapler with a blue cartridge (Echelon, Ethicon, Johnson & Johnson, New Brunswick, NJ, USA) 45 mm into the gut, and running absorbable sutures were used to close the gap (V-loc, Medtronic, Minneapolis, MN, USA). Entero-enterostomy was performed with a 60-mm linear stapler with a white cartridge (Echelon, Ethicon, Johnson & Johnson, New Brunswick, NJ, USA) and running absorbable sutures (V-loc, Medtronic, Minneapolis, MN, USA). At the end of the procedure, the mesenteric defect of the entero-enterostomy was closed with nonabsorbable sutures. Postoperative Follow-up Prior to surgery, patients underwent a structured preoperative program including dietary modification and physical activity. Postoperatively, all patients underwent a standardized follow-up examination at our institution. Furthermore, after surgery, all patients were given multivitamins, calcium and vitamin D, as recommended by the S3 guidelines of the AWMF [ 6 ]. Outcomes Resolution of T2DM was defined as an HbA1c level < 6.5% without the need for antidiabetic medication. Resolution of aHT was defined as a median blood pressure < 140/90 mmHg without the need for antihypertensive medication. Patients requiring continuous positive airway pressure (CPAP) were classified as having OSAS. Resolution of GERD was defined as a reduction in or disappearance of symptoms and related complications. Patients with grade I iron deficiency receive oral iron supplements, whereas patients with grade II iron deficiency receive intravenous iron supplements, usually administered in an ambulant setting. Grade III iron deficiency require hospital-based treatment involving red blood cell transfusions. Postoperative complications were defined as the need for computertomographie-scan (CT-scan) or endoscopy, or hospital readmission caused by MBS, within one year after surgery. To assess QoL and satisfaction with body weight, we extracted data for the Bariatric Quality of Life (BQL) Index from the Quality Assurance Registry of the German Society for General and Visceral Surgery (StuDoQ, DGAV); responses to this questionnaire are provided on a numeric scale from 1 to 5, where 1 indicates “very poor” and 5 indicates “very good.” Statistical Methods In this study, frequency data are reported as absolute and relative frequencies (%), and numerical data are reported as the arithmetic mean, the standard deviation (as a measure of variability), the minimum and maximum, the number of cases, and percentiles. SPSS version 22 (SPSS, 2016) and R version 4.3 were used for analysis. A series of statistical tests was used to explore differences. The main tests used were assumption-free tests (Fisher’s test or rank tests such as the Mann‒Whitney U test or analysis of variance by ranks; Lehmann, 1998). When using these tests, it is not necessary to prove (e.g., from the literature or with data from the population of interest) whether the data are normally distributed and whether the variances are homogeneous (all of these are necessary prerequisites, for example, for analysis of variance (ANOVA)). All of these tests were used purely for exploratory purposes. Therefore, none of the corresponding findings provide proof or are confirmatory. To test differences between the two groups, the Mann‒Whitney U test (Lehmann, 1998), which is used to test differences in continuous data, was used. The Kruskal and Wallis one-way analysis of variance by ranks was used to test multigroup differences. Differences in frequency data were tested using the chi-square test or, if the number of cases was small, the Fisher–Yates test (Bortz & Schuster, 2010). Results T able 1 Patient demographics: no significant differences between patients with NS-RYGB and S-RYGB in gender and age at OP. Baseline characteristics are comparable between groups. The OP-duration is significantly longer in the NS-RYGB group. A total of 242 patients were included in the study and underwent MBS over a period of 3 years, from 07/2019 until 05/2022. The data were assessed preoperatively and 1 year post-operatively. Table 1 shows the patient demographics. Patient characteristics were comparable between the two groups. The patients were predominantly female (75.2%) and in their forties (median age of 45 years). The median operation time was 81.3 minutes and was significantly shorter in the S-RYGB group (74.9 minutes) than in the NS-RYGB group (86.9 minutes; p < 0.001) (Table 1) Two groups of patients were analyzed. Patients in the S-RYGB group (n=113) underwent MBS in which standard limb lengths were selected following the S3 guidelines of the AWMF [6]. Patients in the NS-RYGB group (n=129) underwent LRYGB in which the total SBL was measured intraoperatively, and equal lengths were selected for the BPL and AL, with a CC length of not less than 200 cm. The CC, BPL, and AL lengths selected for different SBLs are shown in Table 2. Table 2 Limb lengths selection of the NS-RYGB group on the basis of the SBL: small bowel length [cm] (SBL), number of patients (n), common channel length [cm], biliopancreatic limb (BPL) and alimentary limb (AL) lengths [cm] Table 3 NS-RYGB group: Intraoperatively measured small bowel length [cm] (SBL), mean (m), standard deviation (sd), minimum (min), median (md), maximum (max), number (n) Before the operation, the mean weight was 128.8 kg (81–205) in the NS-RYGB group and 128.4 (64-193) in the S-RYGB group (Table 4). The mean BMI was preoperative 43.8 (30.2–63.3) in the NS-RYGB group and 44.7 (26-62.6) in the S-RYGB group. The mean postoperative weight loss was 40.5 kg and was comparable between the groups: -39.8 kg in the NS-RYGB group and -41.3 kg in the S-RYGB group. Therefore, we cannot detect a significant difference in weight loss outcome between both groups. Table 4 Changes in body weight [kg] and body mass index (BMI) [kg/m^2] pre- and 1 year post-operative in both groups. Number of cases (n), mean (m), standard deviation (sd), minimum (min), median (md), maximum (max). The postoperative weightloss outcome is comparable between both groups. In conclusion both groups showed comparable baseline characteristics, such as gender and age at MBS. Also, the pre-operative weight and the postoperative weight loss outcome is comparable between groups. Thus, the study population seems to be appropriate for evaluating the impact of the selection of BPL and AL length based on SBL on postoperative outcomes. Table 5 Percentages of patients with aHT, T2DM, reflux and sleep apnea preoperatively and 1 year post-operatively, compared between NS-RYGB group and S-RYGB group. The NS-RYGB group shows significant greater reductions in aHT and T2DM, while resolution of OSAS and GERD is comparable between groups. Table 5 presents the percentages of patients with obesity-related comorbidities and the changes in these percentages after RYGB surgery. A significant difference was found between the groups with respect to the percentages of patients with aHT and T2DM. In the NS-RYGB group, 53.5% of patients had aHT and 23.3% of patients had T2DM before surgery. The percentages of patients with aHT and T2DM decreased to 17.1% and 4.7%, respectively, within 1 year post-operatively. In contrast, the percentages of patients with aHT and T2DM in the S-RYGB group were 62.8% and 22.1%, respectively, before surgery and 35.4% and 13.3%, respectively, after surgery. Thus, the postoperative reductions in the percentages of patients with aHT (p=0.001) and T2DM (p=0.018) were significantly greater in the NS-RYGB group than in the S-RYGB group. The changes in the percentages of patients with OSAS (p=0.580) and GERD (p=0.109) from before to after surgery were not significantly different between the groups (Table 5). These data indicate that the NS-RYGB leads to resolution of obesity-related comorbidities in both groups, with substantially greater reductions of aHT and T2DM in the NS-RYGB group, while outcomes of GERD and OSAS were comparable in both groups. Table 6 Percentage of patients with iron deficiency, requiring hospital readmission, and requiring CT-scan/endoscopy within 1 year post-operatively. The NS-RYGB group shows significant less iron deficiency, hospital readmissions and requires less CT-scans/endoscopies. Overall, 89.1% of patients in the NS-RYGB group did not experience iron deficiency after surgery, 9.3% experienced grade II iron deficiency and 1.6% experienced grade III iron deficiency. In contrast, only 55.8% of patients in the S-RYGB group did not experience iron deficiency, whereas 28.3% experienced grade II iron deficiency and 15.9% experienced grade III iron deficiency. Therefore, grade II and II iron deficiency was significantly less common in the NS-RYGB group than in the S-RYGB group (p < 0.001) (Table 6). Within one year after surgery, 11.6% of patients in the NS-RYGB group but 30.1% of patients in the S-RYGB required hospital readmission, representing a statistically significant difference (p = 0.001). Further, only 10,1% of the NS-RYGB group required CT-scan or endoscopy after MBS, compared with 19,5% in the S-RYGB group (p=0,038). Thus, the data revealed that the percentages of patients with postoperative complications, with the need for CT-scan or endoscopy, and requiring hospital readmission, caused by MBS, were decreased significantly in the NS-RYGB group compared with the S-RYGB group. Table 7 Body weight satisfaction and quality of life (QoL) scores before and after surgery. The data shows significant better outcomes in QoL and satisfaction with body weight in the NS-RYGB group. QoL and body weight satisfaction were also assessed preoperatively and postoperatively. The changes in both QoL and body weight satisfaction were significantly different between the NS-RYGB and S-RYGB groups (p <0.001). Patients in the NS-RYGB group reported an average increase in body weight satisfaction of approximately 4 points and an average increase in QoL of 3 points after surgery. In contrast, patients in the S-RYGB group showed an average increase in body weight satisfaction of approximately 3 points and an average increase in QoL of approximately 2 points after surgery. In conclusion, the data indicates that the NS-RYGB was associated with less postoperative iron deficiency, lower complications within one year after surgery and greater postoperative QoL and satisfaction with body weight, compared with S-RYGB. Discussion In the present study, we aimed to determine whether postoperative outcomes differ between patients undergoing RYGB in which equal BPL and AL lengths are selected based on the total SBL, resulting into a proportional CC length (NS-RYGB), and patients undergoing standard RYGB, in which the total SBL is not measured (S-RYGB). This approach was developed in response to the lack of consensus regarding the optimal lengths for BPL, AL, a standardized recommendation on the CC length. Establishing a proportional limb-lengths concept may reduce variability in postoperative outcomes after RYGB and contributes to a clearer consensus on the optimal limb length. The main findings of our study show that NS-RYGB was associated with a significantly higher resolution of aHT and T2DM in the NS-RYGB group, higher QoL scores and satisfaction with body weight and lower rates of iron deficiency, hospital readmissions and the need for CT-scan or endoscopy due to MBS. One of the key findings of this study was the significantly lower incidence of aHT and T2DM in the NS-RYGB group compared with the S-RYGB group one year after surgery. Since aHT and T2DM have a known endocrine component, these findings suggest that selecting equal BPL and AL lengths adapted to the total SBL may have a beneficial effect on endocrine regulation in individuals with these diseases. These findings are in line with a meta-analysis by Kwon et al. revealed that a longer BPL length leads to a greater likelihood of T2DM resolution within one year after surgery [Kwon, 20]. Another meta-analysis and systematic review by Kamocka et al. also revealed that a longer BPL length promotes the resolution of aHT and T2DM [ 21 ]. In contrast, the prevalence of GERD and OSAS decreased to a comparable extent in both groups within one year after surgery. This may indicate a direct association of GERD and OSAS with body weight loss, which was equivalent between the two groups. In conclusion, these findings suggest that a proportional limb length selection improves postoperative outcomes of endocrine comorbidities, such as aHT and T2DM, whereas weight-loss-dependant comorbidities, such as GERD and OSAS, do not appear to be impacted by this approach. Contrary to our expectations, we found that significantly fewer patients in the NS-RYGB group experienced iron deficiency. A multicentric randomized controlled trial by Leeman et al. compared S-RYGB to very long Roux-en-Y limb RYGB (VLRL-RYGB), with a BPL length of 60 cm in both groups. The researchers reported significantly higher rates of malnutrition, including iron deficiency, in the VLRL-RYGB group, which may be due to the shorter CC length, one year after surgery [ 22 ]. This finding supports the hypothesis that a shorter CC could contribute to postoperative iron deficiency. The lower percentage of patients with iron deficiency in the NS-RYGB group in our study may have been due to the adaptation of the BPL and AL length to the total SBL, as this may have led the CC to be long enough to prevent iron deficiency within one year after surgery. Further investigations are needed to determine whether the lower prevalence of iron deficiency after NS-RYGB is maintained in the long term. The mean total SBL of all patients in the NS-RYGB group was 585 cm (350–830). This finding is comparable to the findings of Gislasson et al., who reported a mean total SBL of 620 cm (420–870) [ 23 ]. There is strong evidence that the extent of malabsorption after gastric bypass surgery is influenced mainly by the length of the CC rather than by the length of the BPL or AL [ 15 ]. When the BPL and AL are extended, more tissue is taken from the small bowel at the expense of the CC. Thus, patients with a short SBL may have a greater risk for postoperative malnutrition. When we adapted the BPL and AL length to the total SBL, the median CC length was 373.4 cm (210–590). Therefore, in the NS-RYGB group, the CC was likely long enough to avoid iron deficiency. Importantly, the change in BMI within one year after surgery was comparable between the two groups in our study. In contrast to other studies, we did not observe significantly higher change in BMI when the BLP and AL length were adapted to the SBL. In both groups, the mean postoperative weight loss was between 39.8 and 41.3 kg within one year after surgery. Consistent to our findings, a randomized controlled trial by Homan et al. initially reported significantly better results in terms of weight loss when a longer BLP length was chosen, although this effect could no longer be detected after four years of follow-up, so the weight-loss was comparable in both groups. Furthermore, Homan et al. did not report significantly better outcomes in terms of the resolution of comorbidities or QoL [ 4 ]. Similarly, a systematic review and meta-analysis by Kamocka et al. reported no differences in BMI-reduction over 12–72 months across studies comparing different lengths of the BPL. Despite some studies showed weight-loss advantages at 24 months when a longer BPL was chosen, these effects did not persist in the long term [ 21 ]. In consensus with the existing literature, our data supports the thesis that equally selected BPL and AL lengths, based on the total SBL, resulting into a proportional CC length, does not substantially influence the weight loss outcome, compared to a S-RYGB. The advantage of this approach appears to lie in improving metabolic and endocrine comorbidities, such as aHT and T2DM, rather than augmenting weight loss itself. Another key finding of this study is that patients in the NS-RYGB group reported significantly greater QoL and satisfaction with body weight than those in the S-RYGB group did at one year after surgery. Significant improvements in QoL accompanied by extensive weight following MBS have been reported by many authors [ 24 ]. The finding that the QoL score of patients in the NS-RYGB group was significantly higher than that of patients in the S-RYGB group at one year after surgery could be attributed to the significantly lower incidence of aHT and T2DM, as it is well known that the resolution of comorbidities such as aHT and T2DM improves QoL [ 25 ]. Furthermore, reducing the need for medication, such as antihypertensive or antidiabetes drugs, can also positively influence QoL [ 26 ]. A systematic review by Tajeu et al. confirmed that extensive weight loss following MBS reduces or eliminates the need for antihypertensive medication in most patients [ 27 ]. Taken together, our findings suggest that implementing NS-RYGB on a broader scale may have a positive influence on the postoperative QoL and satisfaction with body weight, beyond what is commonly achieved with S-RYGB. Interestingly, we noted a significantly lower rate of postoperative complications in the NS-RYGB group within one year after surgery. Thus, we found no evidence that measuring the SBL intraoperatively leads to an increased risk of surgical injury. Currently, the reason for the significantly lower rate of complications in the NS-RYGB group remains unclear, several factors could be considered. One possibility is that the measurement of the SBL, and equal selected BPL and AL lengths, resulting into a proportional CC length, results in a more balanced configuration, which reduces tension or variability of the anastomosis and therefore lowers the risk of postoperative complications. Another hypothesis could be the improved consistency of surgical workflow due to more standardized and structured limb length selection while performing the RYGB. Taken together, these findings indicate that the NS-RYGB may have beneficial effects on the postoperative complication rate. However, further investigations are needed to determine whether proportional limb length selection can reliably reproduce these improved postoperative outcomes and reduced complication rates. Furthermore, the operation time in the NS-RYGB group was on average 12 minutes longer than that in the S-RYGB group. This may be attributed to the time needed for the intraoperative measurement of the SBL and the adaptation of the AL and BPL lengths. This finding is in line with the findings of Soong et al., who found that measuring the total SBL to ensure that the length of the CC remained above 400 cm significantly prolonged the operation time [ 28 ]. Although an increase of operation time is not uncommon when implementing an individualized surgical approach, it raises questions regarding the feasibility and whether this aspect of the NS-RYGB might pose barriers to wider adoption of this procedure, particularly in high-volume centers where operating room efficiency is critical. However, considering that we observed no increase of postoperative complications and identified significantly better outcomes in terms of aHT and T2DM resolution, higher QoL and satisfaction with body weight, and lower rates of iron deficiency one year after NS-RYGB, the longer operation time may not represent a major contraindication to the implementation of this technique. Further investigation is needed to determine whether these clinical benefits can be reproduced more broadly and sustained in the long term. One strength of this study is that it is one of the first studies to provide evidence regarding the optimization of RYGB in relation to the SBL, in which equal BPL and AL lengths are selected based on the total SBL, resulting into a proportional CC length. Furthermore, the group size appears to be sufficient, as 242 patients provide sufficient statistical power to attribute weight loss, changes in QoL and changes in comorbidities to the optimized procedure. However, there are several limitations of the study. The patients were not randomly divided into groups; instead, the preferred procedure at our institution was changed to NS-RYGB and a retrospective data analysis was conducted. Although our study design limits the ability to control for all confounders, the comparable baseline characteristics of the two groups reduce the possibility that group differences were caused by selection bias. Additionally, comparisons with other studies were complicated due to a lack of standardization regarding the definition of limb length in the literature, as some studies refer to “short” limbs and other to “long” limbs, but these terms are used inconsistently in the literature. Moreover, we collected data for only the first postoperative year, preventing us from drawing long-term conclusions; ideally, the same parameters should be reassessed at 3-year and 5-year follow-up examinations. We are currently conducting these follow-up analyses in this same patient cohort, which will allow us to determine whether the observed effects can be reproduced on a broader scale and maintain in the long term. Conclusion Compared with S-RYGB, NS-RYGB - where equal BPL and AL lengths are selected based on the total SBL, resulting into a proportional CC length - leads to significantly better outcomes in terms of QoL, resolution of aHT and T2DM, satisfaction with body weight and iron deficiency, while achieving a similar reduction in BMI. These findings support a more individualized approach and suggest that incorporating proportional limb length selection into RYGB may improve metabolic and QoL-related outcomes. Further long-term studies are needed to confirm these clinical benefits and to determine whether this approach can refine bariatric surgical practice by enhancing long-term metabolic and QoL outcomes. Declarations Compliance with ethical standards The authors declare that they have no conflicts of interest. The authors declare that all procedures involving human patients were conducted in accordance with the Declaration of Helsinki and that all procedures were carried out with the adequate understanding and written informed consent of all patients. Ethical approval was not needed for this retrospective study, as only preexisting, deidentified data from the Quality Assurance Registry of the German Society for General and Visceral Surgery (StuDoQ, DGAV) database were analyzed. Conflict of interest statement Author 1 declares that she has no conflicts of interest. Author 2 declares that he has no conflicts of interest. Author 3 declares that she has no conflicts of interest. Author 4 declares that she has no conflicts of interest. Author 5 declares that she has no conflicts of interest. Author 6 declares that she has no conflicts of interest. Author 7 declares that he has no conflicts of interest. Author 8 declares that he has no conflicts of interest. Funding Sources No funding was received for this study. Data Availability Statement The raw data supporting the conclusions of this article are available from the authors. Author Contribution Luise Eva Köhler contributed to the study design, data acquisition, and drafting of the manuscript.Hinrich Köhler contributed to the study design, data acquisition, and drafting of the manuscript.Ulrich Stefenelli contributed to the statistical analysis and the drafting of the manuscript.Franziska Nieter contributed to the data acquisition.Ioana-Andreea Bollenbach contributed to the drafting of the manuscript.Resa Puffert contributed to the drafting of the manuscript.Clara Böker contributed to the critical revision of the manuscript.Julian W Mall contributed to the concept of the study design, drafting of the manuscript and critical revision of the manuscript. 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Bariatric surgery and obesity: influence on the incretins. Int J Obes Suppl. 2016;6(Suppl 1):S32–6. 10.1038/ijosup.2016.8 . Epub 2016 Nov 16. PMID: 28685028; PMCID: PMC5485883. - German Society for General and Visceral Surgery (DGAV). S3-Guideline: Surgery of Obesity and Metabolic Diseases. Version 2.3, February 2018 (AWMF Registry No. 088 – 001). Accessed. September 2024. - Seidemann L, Moulla Y, Dietrich A. Aktuelle Evidenz zur Schlingenlänge bei intestinalen Bypassverfahren. Die Chirurgie. 2023;94(6):506–11. - Ahmed B, King WC, Gourash W, et al. Proximal Roux-en-Y gastric bypass: Addressing the myth of limb length. Surgery. 2019;166(4):445–55. 10.1016/j.surg.2019.05.046 . Epub 2019 Aug 1. PMID: 31378475; PMCID: PMC6778033. - Tacchino RM. Bowel length: measurement, predictors, and impact on bariatric and metabolic surgery. Surg Obes Relat Dis. 2015;11(2):328–34. 10.1016/j.soard.2014.09.016 . Epub 2014 Sep 30. PMID: 25614357. - Kwon Y, Kim HJ, Lo Menzo E, et al. Anemia, iron and vitamin B12 deficiencies after sleeve gastrectomy compared to Roux-en-Y gastric bypass: a meta-analysis. Surg Obes Relat Dis. 2014;10(4):589–97. Epub 2013 Dec 17. PMID: 24582411. - Elnahas AI, Jackson TD, Hong D. Management of Failed Laparoscopic Roux-en-Y Gastric Bypass. Bariatr Surg Pract Patient Care. 2014;9(1):36–40. 10.1089/bari.2013.0012 . PMID: 24761371; PMCID: PMC3963694. - Mahawar KK, Kumar P, Parmar C, et al. Small bowel limb lengths and Roux-en-Y gastric bypass: a systematic review. Obes Surg. 2016;26(1):196–204. - Shah K, Nergård BJ, Fagerland MW, Gislason H. Limb Length in Gastric Bypass in Super-Obese Patients-Importance of Length of Total Alimentary Small Bowel Tract. Obes Surg. 2019;29(7):2012–2021. 10.1007/s11695-019-03836-1 . PMID: 30929197. - Felsenreich DM, Langer FB, Eichelter J, et al. Bariatric Surgery-How Much Malabsorption Do We Need?-A Review of Various Limb Lengths in Different Gastric Bypass Procedures. J Clin Med. 2021;10(4):674. 10.3390/jcm10040674 . PMID: 33578635; PMCID: PMC7916324. - Stefanidis D, Kuwada TS, Gersin KS. The importance of the length of the limbs for gastric bypass patients–an evidence-based review. Obes Surg. 2011;21(1):119 – 24. 10.1007/s11695-010-0239-3 . PMID: 20680504. - Choban PS, Flancbaum L. The effect of Roux limb lengths on outcome after Roux-en-Y gastric bypass: a prospective, randomized clinical trial. Obes Surg. 2002;12(4):540-5. 10.1381/096089202762252316 . PMID: 12194548. - Shah K, Nergård BJ, Fagerland MW, et al. Failed Roux-en-Y Gastric Bypass-Long-Term Results of Distalization with Total Alimentary Limb Length of 250 or 300 cm. Obes Surg. 2023;33(1):293–302. 10.1007/s11695-022-06388-z . Epub 2022 Dec 2. PMID: 36459358; PMCID: PMC9834116. - Buchwald H, Avidor Y, Braunwald E et al. Bariatric surgery: a systematic review and meta-analysis. JAMA. 2004;292(14):1724-37. 10.1001/jama.292.14.1724 . Erratum in: JAMA. 2005;293(14):1728. PMID: 15479938. - Colquitt JL, Pickett K, Loveman E, et al. Surgery for weight loss in adults. Cochrane Database Syst Rev. 2014;2014(8):CD003641. 10.1002/14651858.CD003641.pub4 . PMID: 25105982; PMCID: PMC9028049. - Kwon Y, Lee S, Kim D et al. Biliopancreatic Limb Length as a Potential Key Factor in Superior Glycemic Outcomes After Roux-en-Y Gastric Bypass in Patients With Type 2 Diabetes: A Meta-Analysis. Diabetes Care. 2022;45(12):3091–3100. 10.2337/dc22-0835 . PMID: 36455123. - Kamocka A, Chidambaram S, Erridge S, et al. Length of biliopancreatic limb in Roux-en-Y gastric bypass and its impact on post-operative outcomes in metabolic and obesity surgery-systematic review and meta-analysis. Int J Obes (Lond). 2022;46(11):1983–91. 10.1038/s41366-022-01186-0 . Epub 2022 Aug 4. PMID: 35927470; PMCID: PMC9584808. - Leeman M, Gadiot RPM, Wijnand JMA, et al. Effects of standard v. very long Roux limb Roux-en-Y gastric bypass on nutrient status: a 1-year follow-up report from the Dutch Common Channel Trial (DUCATI) Study. Br J Nutr. 2020;123(12):1434–40. 10.1017/S0007114520000616 . - Nergaard BJ, Leifsson BG, Hedenbro J, Gislason H. Gastric bypass with long alimentary limb or long pancreato-biliary limb–long-term results on weight loss, resolution of co-morbidities and metabolic parameters. Obes Surg. 2014;24(10):1595–602. 10.1007/s11695-014-1245-7 . PMID: 24744188; PMCID: PMC4153949. - Monpellier VM, Antoniou EE, Aarts EO, et al. Improvement of Health-Related Quality of Life After Roux-en-Y Gastric Bypass Related to Weight Loss. Obes Surg. 2017;27(5):1168–73. 10.1007/s11695-016-2468-6 . PMID: 27896646; PMCID: PMC5403839. - Julia C, Ciangura C, Capuron L, et al. Quality of life after Roux-en-Y gastric bypass and changes in body mass index and obesity-related comorbidities. Diabetes Metab. 2013;39(2):148–54. 10.1016/j.diabet.2012.10.008 . Epub 2013 Jan 10. PMID: 23313223. - Chen WS, Islam MR, Ambepitiya S. Factors associated with patient experiences of the burden of using medicines and health-related quality of life: A cross-sectional study. PLoS ONE. 2022;17(4):e0267593. 10.1371/journal.pone.0267593 . - Tajeu GS, Johnson E, Buccilla M, et al. Changes in Antihypertensive Medication Following Bariatric Surgery. Obes Surg. 2022;32(4):1312–24. 10.1007/s11695-022-05893-5 . Epub 2022 Jan 26. PMID: 35083703; PMCID: PMC9070659. - Soong TC, Almalki OM, Lee WJ, et al. Measuring the small bowel length may decrease the incidence of malnutrition after laparoscopic one-anastomosis gastric bypass with tailored bypass limb. Surg Obes Relat Dis. 2019;15(10):1712–8. Epub 2019 Aug 21. PMID: 31558409. Tables Tables 1 to 7 are available in the Supplementary Files section. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8464981","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":588650786,"identity":"57f802e8-37cb-4eae-b423-38e293dcb757","order_by":0,"name":"Luise Eva Köhler","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDElEQVRIie3RMUvDQBjG8acU7parrm+IJF8hRwaFFj9LQiBZMotbA4WbFNfr53BxDATapavQ0iUi6BpxUdCqLUKLcA1uIvefXo778R4cYLP9wQ7QKb5Hhq/5BOCbg66RsB+EAFG2kd1xQyhqIZSMmgaD+Kpgcf10Q97x+PH2WqDvmUmsHI001iWr5HhG4dEyP1toZOE+0u2tqhAlV25PUazdPJ03qOLCTEbPb/gI/TV5VzTUziydR6iGe0jhAqUXlGzidhRFRHyy3hIZHybulHOBxJMVS+SlIqlFzhY6yKRpyyHP7psXnApvqmT9qgY+8enDUpz3fdOWbduPEAEQtIPdeP27+zabzfbf+wT8N1CLD3Sa9AAAAABJRU5ErkJggg==","orcid":"","institution":"Herzogin Elisabeth Hospital","correspondingAuthor":true,"prefix":"","firstName":"Luise","middleName":"Eva","lastName":"Köhler","suffix":""},{"id":588650787,"identity":"a93987fc-4245-43fe-a1c8-cc66e1e64bfd","order_by":1,"name":"Ulrich Stefenelli","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Ulrich","middleName":"","lastName":"Stefenelli","suffix":""},{"id":588650788,"identity":"0ccbaac7-3ad8-41cf-b484-de52ded71542","order_by":2,"name":"Resa Puffert","email":"","orcid":"","institution":"Hannover Medical School","correspondingAuthor":false,"prefix":"","firstName":"Resa","middleName":"","lastName":"Puffert","suffix":""},{"id":588650789,"identity":"6673c21b-0108-47b6-bd3b-bfd32a1e1038","order_by":3,"name":"Ioana Andreea Bollenbach","email":"","orcid":"","institution":"Herzogin Elisabeth Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ioana","middleName":"Andreea","lastName":"Bollenbach","suffix":""},{"id":588650790,"identity":"ee865b0b-0e10-4935-80c1-7d5f61429566","order_by":4,"name":"Franziska Nieter","email":"","orcid":"","institution":"Herzogin Elisabeth Hospital","correspondingAuthor":false,"prefix":"","firstName":"Franziska","middleName":"","lastName":"Nieter","suffix":""},{"id":588650791,"identity":"a8b715f2-5df0-42e0-8ad2-f3a60d3a1a3d","order_by":5,"name":"Clara Böker","email":"","orcid":"","institution":"Klinikum Region Hannover","correspondingAuthor":false,"prefix":"","firstName":"Clara","middleName":"","lastName":"Böker","suffix":""},{"id":588650792,"identity":"5c8159e3-6220-4ed2-bdad-b6f08632b34a","order_by":6,"name":"Julian W Mall","email":"","orcid":"","institution":"Klinikum Region Hannover","correspondingAuthor":false,"prefix":"","firstName":"Julian","middleName":"W","lastName":"Mall","suffix":""},{"id":588650793,"identity":"4ed128b7-1660-4130-9603-b1968a106c7a","order_by":7,"name":"Hinrich Köhler","email":"","orcid":"","institution":"Herzogin Elisabeth Hospital","correspondingAuthor":false,"prefix":"","firstName":"Hinrich","middleName":"","lastName":"Köhler","suffix":""}],"badges":[],"createdAt":"2025-12-28 09:38:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8464981/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8464981/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102626506,"identity":"0a189e53-5869-4468-8615-427965614f13","added_by":"auto","created_at":"2026-02-13 17:55:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":610895,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8464981/v1/7c22f2f7-f722-4097-8516-d24d8a7f3b31.pdf"},{"id":102626445,"identity":"5ab7ef90-4038-4fa1-b269-ee8880b2242e","added_by":"auto","created_at":"2026-02-13 17:55:36","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":342993,"visible":true,"origin":"","legend":"","description":"","filename":"TablesandFigures.docx","url":"https://assets-eu.researchsquare.com/files/rs-8464981/v1/3c8139b8b18c647e8e092f62.docx"},{"id":102626444,"identity":"d7ba3574-7bc5-41fd-80ee-68fab42e4ef5","added_by":"auto","created_at":"2026-02-13 17:55:36","extension":"pptx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":504466,"visible":true,"origin":"","legend":"","description":"","filename":"LLVISUALABSTRACTOBSU.2.pptx","url":"https://assets-eu.researchsquare.com/files/rs-8464981/v1/33c7ad9368b9056c47db6f84.pptx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Small bowel length in RYGB: Does limb length matter? Questions remain; Adapting the biliopancreatic and alimentary limb lengths to the total small bowel length in RYGB leads to better postoperative outcomes, such as quality of life, satisfaction with body weight, resolution of comorbidities and iron deficiency","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLaparoscopic Roux-en-Y gastric bypass (RYGB) is the most common surgical procedure for treatment of morbid obesity. According to the IFSO Worldwide Survey, 604,099 bariatric procedures, of which 159,543 Roux-en-Y gastric bypass (RYGB) procedures were performed in 2021 [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. RYGB results in significant weight loss, i.e. a decrease in BMI of approximately 15 points and 60\u0026ndash;70% sustainable excess weight loss (EWL) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. In the western world, RYGB is considered the gold standard of metabolic and bariatric surgery (MBS).\u003c/p\u003e \u003cp\u003eDespite its efficacy, RYGB shows considerable interindividual variability in metabolic outcomes [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Furthermore, nutritional deficiencies, particularly iron deficiency, remains common [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. These inconsistencies may be related to the use of fixed limb lengths that do not consider variations in SBL [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Therefore, selecting equal lengths for BPL and AL, taking the SBL into account, and resulting in a proportional adjustet CC length, may improve metabolic and nutritional outcomes.\u003c/p\u003e \u003cp\u003eIn contrast to earlier assumption, RYGB does not merely prevent the absorption of nutrients and decrease the digestion time. Studies have shown that RYGB leads to weight loss through complex metabolic changes, including increases in the serum concentrations of bile acids and increases in the supply of nutrients and bile acids to the ileum [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan additionalcitationids=\"CR21 CR22\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Furthermore, the secretion of incretins following the ingestion of nutrients, especially glucagon-like peptide-1 (GLP-1), is significantly enhanced after RYGB. This is caused by the accelerated transport of nutritional elements from the gastric pouch to the distal ileum [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe selection of limb lengths in RYGB may affect weight loss outcomes and the occurrence of nutritional deficiencies or comorbidities [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn a recent review, Dietrich et al described significant variations in the SBL among individuals and recommended that the length of the CC should not be less than 200 cm. Additionally, they recommended to measure the total SBL prior to RYGB [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] to avoid malnutrition. A small number of patients seem to have a very short total SBL. Tacchino et al. measured the total SBL of 443 individuals and reported that it was \u0026lt;\u0026thinsp;400 cm or \u0026gt;\u0026thinsp;800 cm in 20% of the individuals [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn contrast, it may be assumed that patients with a SBL\u0026thinsp;\u0026gt;\u0026thinsp;800 cm could benefit from a longer BLP and AL length, as the use of fixed limb lengths result in a proportionally longer CC, which reduces malabsorbtion and metabolic effects and may contributes to weight loss failure, as 30% of patients experience gastric bypass failure, defined as a percentage of EWL less than 50% [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAnother multicenter US cohort study revealed that the CC length is highly variable between individuals [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Most surgeons performing RYGB measure the length of the AL and BPL but not that of the CC because measuring the length of the CC can lead to a longer operation time or small bowel injury [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEarly research focused on the impact of the AL length on RYGB outcomes. Historically, the primary aim of the Roux-Y procedure was to prevent bile reflux. Thus, randomized controlled trials (RCTs) have focused on the AL length. However, evidence suggests that lengthening the AL does not provide a weight loss benefit in patients with a BMI\u0026thinsp;\u0026lt;\u0026thinsp;50 kg/m^2 [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Furthermore, few studies have investigated the influence of the BPL length on weight loss, quality of life (QoL) and comorbidities, especially in the long term. For instance, Homan et al found a significant higher %EWL for the first postoperative years, but no difference in long-term %TWL when lengthening the BPL to 150 cm, compared with standard RYGB [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn contrast, Mahawar et al and Gislasson et al demonstrated that choosing a longer BPL length appears to have a more beneficial effect on weight and comorbidities than choosing a longer AL length does [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Felsenreich et al suggested that if the BPL length is longer than 150 cm, the total SBL should be measured to ensure a sufficient CC length. Furthermore, at least 300 cm of the small bowel (the CC and AL) should remain in the food stream to prevent deficiencies and malnutrition [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA systematic review by Stefanidis et al. revealed that the extent of malabsorption after gastric bypass is influenced mainly by the length of the CC rather than the length of the AL or BPL. Furthermore, they reported that a longer AL and BPL lead to a shorter CC, which may contribute to malnutrition [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCurrently, there is no scientific consensus regarding the optimal BPL or alimentary limb (AL) length relative to the SBL in RYGB. Moreover, although the S3 guidelines of the AWMF suggest a BPL length of 50\u0026ndash;80 cm and an AL length of 150\u0026ndash;200 cm [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], there are currently no recommendations regarding the length of the common channel (CC). It is well known that the selection of BPL and AL lengths directly determine the length of the CC. In individuals with a very short total SBL, there is a risk of creating a very short CC during RYGB, which increases the risk of malnutrition, particularly leading to anemia and iron and vitamin B12 deficiency [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn consequence of not defining a clear consensus about the optimal lengths for BPL and AL there is no standardized recommendation on the CC length. Current guidelines, such as the AWMF guideline, provide general recommendations, but do not define an ideal configuration for the selection of limb length [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This lack of evidence represents a substantial knowledge gap addressed in the present study.\u003c/p\u003e \u003cp\u003eIn this study, we aimed to determine whether postoperative outcomes differ between patients undergoing RYGB in which equal BPL and AL lengths are selected based on the total SBL, resulting into a proportional CC length, and patients undergoing standard RYGB, in which the total SBL is not measured. Considering these findings and the absence of standardized recommendations regarding limb length, we switched from performing standard RYGB (S-RYGB) to new standard RYGB (NS-RYGB) at our institution in July 2021, which represents a complete novel method at our institution. For NS-RYGB, we measured the total SBL intraoperatively and selected equal lengths for the BPL and AL depending on the total SBL. Patient records and follow-up examination data were retrospectively analyzed to determine whether postoperative outcomes differ between patients undergoing RYGP in which equal BPL and AL lengths are selected based on the total SBL and patients undergoing S-RYGP in which the total SBL is not measured. The primary endpoints were the change in body mass index (BMI) and the change in health-related QoL from before surgery to the one-year follow-up. Secondary endpoints included changes in obesity-related comorbidities, patient satisfaction with body weight, iron deficiency incidence, and procedure-related complications before surgery and at the 1-year follow-up.\u003c/p\u003e \u003cp\u003eThis approach represents a new concept that may reduce variability in postoperative outcomes after RYGB and contributes to a clearer consensus on the optimal limb length.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eIn this study, data that were prospectively collected for patients who underwent MBS at the Obesity Center of Herzogin Elisabeth Hospital in Braunschweig, Germany were retrospectively analyzed. A total of 242 patients were included. The clinical data were prospectively documented in the Quality Assurance Registry of the German Society for General and Visceral Surgery (StuDoQ, DGAV). This study was performed in accordance with the Declaration of Helsinki.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePatient selection/Study population\u003c/h2\u003e \u003cp\u003ePatients were selected and managed by a multidisciplinary team, consisting of bariatic surgeons and clinical nutritionists. Patients with a BMI\u0026thinsp;\u0026gt;\u0026thinsp;40 kg/m\u0026sup2; or a BMI\u0026thinsp;\u0026gt;\u0026thinsp;35 kg/m\u0026sup2; and obesity-related comorbidities, in accordance with the interdisciplinary European guidelines on severe obesity [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], were included in this study. Exclusion criteria contain refusal of informed consent, incomplete or missing follow-up data, language barrier or severe comorbidities, for e.g. renal diseases (GFS\u0026thinsp;\u0026lt;\u0026thinsp;30 mL/min), indicating a contraindication for bariatric surgery. All patients were informed about the details of the procedure, benefits and potential risks and were asked if they participate to studies. All patients provided written informed consent to officially confirm participation in the study.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEthical approval\u003c/strong\u003e \u003cp\u003ewas not needed for this retrospective study, as only preexisting, deidentified data from the Quality Assurance Registry of the German Society for General and Visceral Surgery (StuDoQ, DGAV) database were analyzed.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eData collection\u003c/h3\u003e\n\u003cp\u003eThe dataset consisted of patient demographics (age, sex, and BMI), operative details (duration of surgery, CC, BPL, and AL length in cm and total SBL length in cm), and information on the incidence of obesity-associated comorbidities such as arterial hypertension (aHT), type 2 diabetes mellitus (T2DM), obstructive sleep apnea syndrome (OSAS), and gastroesophageal reflux disease (GERD). Additional parameters included iron deficiency, as a type of malnutrition; postoperative complications within one year; QoL and satisfaction with body weight.\u003c/p\u003e \u003cp\u003eData were obtained preoperatively, at 1 year post-operatively and annually thereafter. The procedures were performed by the same surgical team, led by PD Dr. med. habil H. K\u0026ouml;hler.\u003c/p\u003e\n\u003ch3\u003ePatient groups\u003c/h3\u003e\n\u003cp\u003eIn this study, two groups were compared. The first group consisted of 113 patients who underwent RYGB in which standard limb lengths were chosen for the BPL and AL, such as a BPL length of 50\u0026ndash;80 cm and an AL length of 150\u0026ndash;200 cm, following the S3 guidelines of the AWMF [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] (S-RYGB), from 07/2019 until 11/2020. As we switched from performing S-RYGB to NS-RYGB at our institution in 07/2021, the second group consisted of 129 patients who underwent RYGB in which the total SBL was measured, and equal lengths were selected for the BPL and AL based on the SBL, resulting into a proportional CC length, between 07/2021 and 05/2022. Until today, no identical surgical approach has been described in the literature, thus our method is novel.\u003c/p\u003e\n\u003ch3\u003eSurgical Procedure\u003c/h3\u003e\n\u003cp\u003eRYGB was performed laparoscopically in an antecolic and antegastric manner in all patients. A small gastric pouch of 40\u0026ndash;50 mL was constructed using a 60-mm linear stapler with a blue cartridge (Echelon, Ethicon, Johnson \u0026amp; Johnson, New Brunswick, NJ, USA). The small bowel was measured using a marked grasper. For S-RYGB, the small bowel was separated 80 cm below the ligament of Treitz, a gastroenterostomy was created, and an AL length of 150 cm was selected. For NS-RYGB, the whole bowel was measured from the ligament of Treitz to the ileocecal valve; the small bowel was separated (70\u0026ndash;150 cm) below the ligament of Treitz depending on the total SBL; and the selected AL length was the same as the selected BPL length. In both procedures, anastomosis was performed in the same manner.\u003c/p\u003e \u003cp\u003eFor patients with an SBL\u0026thinsp;\u0026lt;\u0026thinsp;500 cm, a minimum CC length of 200 cm and BPL and AL lengths\u0026thinsp;\u0026le;\u0026thinsp;100 cm was selected. For patients with an SBL of 500\u0026ndash;700 cm, a CC length of \u0026gt;\u0026thinsp;280 cm, and BPL and AL lengths of 100\u0026ndash;120 cm was selected. For patients with an SBL\u0026thinsp;\u0026gt;\u0026thinsp;700 cm, a CC length of \u0026gt;\u0026thinsp;360 cm and BPL and AL lengths of \u0026ge;\u0026thinsp;120 cm was selected.\u003c/p\u003e \u003cp\u003eGastrojejunostomy was performed by inserting a 60-mm linear stapler with a blue cartridge (Echelon, Ethicon, Johnson \u0026amp; Johnson, New Brunswick, NJ, USA) 45 mm into the gut, and running absorbable sutures were used to close the gap (V-loc, Medtronic, Minneapolis, MN, USA). Entero-enterostomy was performed with a 60-mm linear stapler with a white cartridge (Echelon, Ethicon, Johnson \u0026amp; Johnson, New Brunswick, NJ, USA) and running absorbable sutures (V-loc, Medtronic, Minneapolis, MN, USA). At the end of the procedure, the mesenteric defect of the entero-enterostomy was closed with nonabsorbable sutures.\u003c/p\u003e\n\u003ch3\u003ePostoperative Follow-up\u003c/h3\u003e\n\u003cp\u003ePrior to surgery, patients underwent a structured preoperative program including dietary modification and physical activity. Postoperatively, all patients underwent a standardized follow-up examination at our institution. Furthermore, after surgery, all patients were given multivitamins, calcium and vitamin D, as recommended by the S3 guidelines of the AWMF [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eOutcomes\u003c/h2\u003e \u003cp\u003eResolution of T2DM was defined as an HbA1c level\u0026thinsp;\u0026lt;\u0026thinsp;6.5% without the need for antidiabetic medication. Resolution of aHT was defined as a median blood pressure\u0026thinsp;\u0026lt;\u0026thinsp;140/90 mmHg without the need for antihypertensive medication. Patients requiring continuous positive airway pressure (CPAP) were classified as having OSAS. Resolution of GERD was defined as a reduction in or disappearance of symptoms and related complications.\u003c/p\u003e \u003cp\u003ePatients with grade I iron deficiency receive oral iron supplements, whereas patients with grade II iron deficiency receive intravenous iron supplements, usually administered in an ambulant setting. Grade III iron deficiency require hospital-based treatment involving red blood cell transfusions.\u003c/p\u003e \u003cp\u003ePostoperative complications were defined as the need for computertomographie-scan (CT-scan) or endoscopy, or hospital readmission caused by MBS, within one year after surgery.\u003c/p\u003e \u003cp\u003eTo assess QoL and satisfaction with body weight, we extracted data for the Bariatric Quality of Life (BQL) Index from the Quality Assurance Registry of the German Society for General and Visceral Surgery (StuDoQ, DGAV); responses to this questionnaire are provided on a numeric scale from 1 to 5, where 1 indicates \u0026ldquo;very poor\u0026rdquo; and 5 indicates \u0026ldquo;very good.\u0026rdquo;\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStatistical Methods\u003c/h3\u003e\n\u003cp\u003eIn this study, frequency data are reported as absolute and relative frequencies (%), and numerical data are reported as the arithmetic mean, the standard deviation (as a measure of variability), the minimum and maximum, the number of cases, and percentiles. SPSS version 22 (SPSS, 2016) and R version 4.3 were used for analysis.\u003c/p\u003e \u003cp\u003eA series of statistical tests was used to explore differences. The main tests used were assumption-free tests (Fisher\u0026rsquo;s test or rank tests such as the Mann‒Whitney U test or analysis of variance by ranks; Lehmann, 1998). When using these tests, it is not necessary to prove (e.g., from the literature or with data from the population of interest) whether the data are normally distributed and whether the variances are homogeneous (all of these are necessary prerequisites, for example, for analysis of variance (ANOVA)). All of these tests were used purely for exploratory purposes. Therefore, none of the corresponding findings provide proof or are confirmatory.\u003c/p\u003e \u003cp\u003eTo test differences between the two groups, the Mann‒Whitney U test (Lehmann, 1998), which is used to test differences in continuous data, was used. The Kruskal and Wallis one-way analysis of variance by ranks was used to test multigroup differences. Differences in frequency data were tested using the chi-square test or, if the number of cases was small, the Fisher\u0026ndash;Yates test (Bortz \u0026amp; Schuster, 2010).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eT\u003c/strong\u003e\u003cstrong\u003eable 1\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatient demographics: no significant differences between patients with NS-RYGB and S-RYGB in gender and age at OP. Baseline characteristics are comparable between groups. The OP-duration is significantly longer in the NS-RYGB group.\u003c/p\u003e\n\u003cp\u003eA total of 242 patients were included in the study and underwent MBS over a period of 3 years, from 07/2019 until 05/2022. The data were assessed preoperatively and 1 year post-operatively.\u003c/p\u003e\n\u003cp\u003eTable 1 shows the patient demographics. Patient characteristics were comparable between the two groups. The patients were predominantly female (75.2%) and in their forties (median age of 45 years). The median operation time was 81.3 minutes and was significantly shorter in the S-RYGB group (74.9 minutes) than in the NS-RYGB group (86.9 minutes; p \u0026lt; 0.001) (Table 1)\u003c/p\u003e\n\u003cp\u003eTwo groups of patients were analyzed. Patients in the S-RYGB group (n=113) underwent MBS in which standard limb lengths were selected following the S3 guidelines of the AWMF [6]. Patients in the NS-RYGB group (n=129) underwent LRYGB in which the total SBL was measured intraoperatively, and equal lengths were selected for the BPL and AL, with a CC length of not less than 200 cm. The CC, BPL, and AL lengths selected for different SBLs are shown in Table 2.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLimb lengths selection of the NS-RYGB group on the basis of the SBL: small bowel length [cm] (SBL), number of patients (n), common channel length [cm], biliopancreatic limb (BPL) and alimentary limb (AL) lengths [cm]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNS-RYGB group: Intraoperatively measured small bowel length [cm] (SBL), mean (m), standard deviation (sd), minimum (min), median (md), maximum (max), number (n)\u003c/p\u003e\n\u003cp\u003eBefore the operation, the mean weight was 128.8 kg (81\u0026ndash;205) in the NS-RYGB group and 128.4 (64-193) in the S-RYGB group (Table 4). The mean BMI was preoperative 43.8 (30.2\u0026ndash;63.3) in the NS-RYGB group and 44.7 (26-62.6) in the S-RYGB group. The mean postoperative weight loss was 40.5 kg and was comparable between the groups: -39.8 kg in the NS-RYGB group and -41.3 kg in the S-RYGB group. Therefore, we cannot detect a significant difference in weight loss outcome between both groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eChanges in body weight [kg] and body mass index (BMI) [kg/m^2] pre- and 1 year post-operative in both groups. Number of cases (n), mean (m), standard deviation (sd), minimum (min), median (md), maximum (max). The postoperative weightloss outcome is comparable between both groups.\u003c/p\u003e\n\u003cp\u003eIn conclusion both groups showed comparable baseline characteristics, such as gender and age at MBS. Also, the pre-operative weight and the postoperative weight loss outcome is comparable between groups. Thus, the study population seems to be appropriate for evaluating the impact of the selection of BPL and AL length based on SBL on postoperative outcomes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePercentages of patients with aHT, T2DM, reflux and sleep apnea preoperatively and 1 year post-operatively, compared between NS-RYGB group and S-RYGB group. The NS-RYGB group shows significant greater reductions in aHT and T2DM, while resolution of OSAS and GERD is comparable between groups.\u003c/p\u003e\n\u003cp\u003eTable 5 presents the percentages of patients with obesity-related comorbidities and the changes in these percentages after RYGB surgery. A significant difference was found between the groups with respect to the percentages of patients with aHT and T2DM. In the NS-RYGB group, 53.5% of patients had aHT and 23.3% of patients had T2DM before surgery. The percentages of patients with aHT and T2DM decreased to 17.1% and 4.7%, respectively, within 1 year post-operatively. In contrast, the percentages of patients with aHT and T2DM in the S-RYGB group were 62.8% and 22.1%, respectively, before surgery and 35.4% and 13.3%, respectively, after surgery.\u003c/p\u003e\n\u003cp\u003e\u003cbr /\u003e Thus, the postoperative reductions in the percentages of patients with aHT (p=0.001) and T2DM (p=0.018) were significantly greater in the NS-RYGB group than in the S-RYGB group. The changes in the percentages of patients with OSAS (p=0.580) and GERD (p=0.109) from before to after surgery were not significantly different between the groups (Table 5). These data indicate that the NS-RYGB leads to resolution of obesity-related comorbidities in both groups, with substantially greater reductions of aHT and T2DM in the NS-RYGB group, while outcomes of GERD and OSAS were comparable in both groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 6\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePercentage of patients with iron deficiency, requiring hospital readmission, and requiring CT-scan/endoscopy within 1 year post-operatively. The NS-RYGB group shows significant less iron deficiency, hospital readmissions and requires less CT-scans/endoscopies.\u003c/p\u003e\n\u003cp\u003eOverall, 89.1% of patients in the NS-RYGB group did not experience iron deficiency after surgery, 9.3% experienced grade II iron deficiency and 1.6% experienced grade III iron deficiency. In contrast, only 55.8% of patients in the S-RYGB group did not experience iron deficiency, whereas 28.3% experienced grade II iron deficiency and 15.9% experienced grade III iron deficiency. Therefore, grade II and II iron deficiency was significantly less common in the NS-RYGB group than in the S-RYGB group (p \u0026lt; 0.001) (Table 6).\u003c/p\u003e\n\u003cp\u003eWithin one year after surgery, 11.6% of patients in the NS-RYGB group but 30.1% of patients in the S-RYGB required hospital readmission, representing a statistically significant difference (p = 0.001). Further, only 10,1% of the NS-RYGB group required CT-scan or endoscopy after MBS, compared with 19,5% in the S-RYGB group (p=0,038). Thus, the data revealed that the percentages of patients with postoperative complications, with the need for CT-scan or endoscopy, and requiring hospital readmission, caused by MBS, were decreased significantly in the NS-RYGB group compared with the S-RYGB group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 7\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBody weight satisfaction and quality of life (QoL) scores before and after surgery. The data shows significant better outcomes in QoL and satisfaction with body weight in the NS-RYGB group.\u003c/p\u003e\n\u003cp\u003eQoL and body weight satisfaction were also assessed preoperatively and postoperatively. The changes in both QoL and body weight satisfaction were significantly different between the NS-RYGB and S-RYGB groups (p \u0026lt;0.001). Patients in the NS-RYGB group reported an average increase in body weight satisfaction of approximately 4 points and an average increase in QoL of 3 points after surgery. In contrast, patients in the S-RYGB group showed an average increase in body weight satisfaction of approximately 3 points and an average increase in QoL of approximately 2 points after surgery. In conclusion, the data indicates that the NS-RYGB was associated with less postoperative iron deficiency, lower complications within one year after surgery and greater postoperative QoL and satisfaction with body weight, compared with S-RYGB.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn the present study, we aimed to determine whether postoperative outcomes differ between patients undergoing RYGB in which equal BPL and AL lengths are selected based on the total SBL, resulting into a proportional CC length (NS-RYGB), and patients undergoing standard RYGB, in which the total SBL is not measured (S-RYGB). This approach was developed in response to the lack of consensus regarding the optimal lengths for BPL, AL, a standardized recommendation on the CC length. Establishing a proportional limb-lengths concept may reduce variability in postoperative outcomes after RYGB and contributes to a clearer consensus on the optimal limb length.\u003c/p\u003e \u003cp\u003eThe main findings of our study show that NS-RYGB was associated with a significantly higher resolution of aHT and T2DM in the NS-RYGB group, higher QoL scores and satisfaction with body weight and lower rates of iron deficiency, hospital readmissions and the need for CT-scan or endoscopy due to MBS.\u003c/p\u003e \u003cp\u003eOne of the key findings of this study was the significantly lower incidence of aHT and T2DM in the NS-RYGB group compared with the S-RYGB group one year after surgery. Since aHT and T2DM have a known endocrine component, these findings suggest that selecting equal BPL and AL lengths adapted to the total SBL may have a beneficial effect on endocrine regulation in individuals with these diseases. These findings are in line with a meta-analysis by Kwon et al. revealed that a longer BPL length leads to a greater likelihood of T2DM resolution within one year after surgery [Kwon, 20]. Another meta-analysis and systematic review by Kamocka et al. also revealed that a longer BPL length promotes the resolution of aHT and T2DM [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn contrast, the prevalence of GERD and OSAS decreased to a comparable extent in both groups within one year after surgery. This may indicate a direct association of GERD and OSAS with body weight loss, which was equivalent between the two groups.\u003c/p\u003e \u003cp\u003eIn conclusion, these findings suggest that a proportional limb length selection improves postoperative outcomes of endocrine comorbidities, such as aHT and T2DM, whereas weight-loss-dependant comorbidities, such as GERD and OSAS, do not appear to be impacted by this approach.\u003c/p\u003e \u003cp\u003eContrary to our expectations, we found that significantly fewer patients in the NS-RYGB group experienced iron deficiency. A multicentric randomized controlled trial by Leeman et al. compared S-RYGB to very long Roux-en-Y limb RYGB (VLRL-RYGB), with a BPL length of 60 cm in both groups. The researchers reported significantly higher rates of malnutrition, including iron deficiency, in the VLRL-RYGB group, which may be due to the shorter CC length, one year after surgery [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. This finding supports the hypothesis that a shorter CC could contribute to postoperative iron deficiency. The lower percentage of patients with iron deficiency in the NS-RYGB group in our study may have been due to the adaptation of the BPL and AL length to the total SBL, as this may have led the CC to be long enough to prevent iron deficiency within one year after surgery. Further investigations are needed to determine whether the lower prevalence of iron deficiency after NS-RYGB is maintained in the long term.\u003c/p\u003e \u003cp\u003eThe mean total SBL of all patients in the NS-RYGB group was 585 cm (350\u0026ndash;830). This finding is comparable to the findings of Gislasson et al., who reported a mean total SBL of 620 cm (420\u0026ndash;870) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. There is strong evidence that the extent of malabsorption after gastric bypass surgery is influenced mainly by the length of the CC rather than by the length of the BPL or AL [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. When the BPL and AL are extended, more tissue is taken from the small bowel at the expense of the CC. Thus, patients with a short SBL may have a greater risk for postoperative malnutrition. When we adapted the BPL and AL length to the total SBL, the median CC length was 373.4 cm (210\u0026ndash;590). Therefore, in the NS-RYGB group, the CC was likely long enough to avoid iron deficiency.\u003c/p\u003e \u003cp\u003eImportantly, the change in BMI within one year after surgery was comparable between the two groups in our study. In contrast to other studies, we did not observe significantly higher change in BMI when the BLP and AL length were adapted to the SBL. In both groups, the mean postoperative weight loss was between 39.8 and 41.3 kg within one year after surgery. Consistent to our findings, a randomized controlled trial by Homan et al. initially reported significantly better results in terms of weight loss when a longer BLP length was chosen, although this effect could no longer be detected after four years of follow-up, so the weight-loss was comparable in both groups. Furthermore, Homan et al. did not report significantly better outcomes in terms of the resolution of comorbidities or QoL [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Similarly, a systematic review and meta-analysis by Kamocka et al. reported no differences in BMI-reduction over 12\u0026ndash;72 months across studies comparing different lengths of the BPL. Despite some studies showed weight-loss advantages at 24 months when a longer BPL was chosen, these effects did not persist in the long term [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn consensus with the existing literature, our data supports the thesis that equally selected BPL and AL lengths, based on the total SBL, resulting into a proportional CC length, does not substantially influence the weight loss outcome, compared to a S-RYGB. The advantage of this approach appears to lie in improving metabolic and endocrine comorbidities, such as aHT and T2DM, rather than augmenting weight loss itself.\u003c/p\u003e \u003cp\u003eAnother key finding of this study is that patients in the NS-RYGB group reported significantly greater QoL and satisfaction with body weight than those in the S-RYGB group did at one year after surgery. Significant improvements in QoL accompanied by extensive weight following MBS have been reported by many authors [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The finding that the QoL score of patients in the NS-RYGB group was significantly higher than that of patients in the S-RYGB group at one year after surgery could be attributed to the significantly lower incidence of aHT and T2DM, as it is well known that the resolution of comorbidities such as aHT and T2DM improves QoL [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Furthermore, reducing the need for medication, such as antihypertensive or antidiabetes drugs, can also positively influence QoL [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. A systematic review by Tajeu et al. confirmed that extensive weight loss following MBS reduces or eliminates the need for antihypertensive medication in most patients [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTaken together, our findings suggest that implementing NS-RYGB on a broader scale may have a positive influence on the postoperative QoL and satisfaction with body weight, beyond what is commonly achieved with S-RYGB.\u003c/p\u003e \u003cp\u003eInterestingly, we noted a significantly lower rate of postoperative complications in the NS-RYGB group within one year after surgery. Thus, we found no evidence that measuring the SBL intraoperatively leads to an increased risk of surgical injury. Currently, the reason for the significantly lower rate of complications in the NS-RYGB group remains unclear, several factors could be considered. One possibility is that the measurement of the SBL, and equal selected BPL and AL lengths, resulting into a proportional CC length, results in a more balanced configuration, which reduces tension or variability of the anastomosis and therefore lowers the risk of postoperative complications. Another hypothesis could be the improved consistency of surgical workflow due to more standardized and structured limb length selection while performing the RYGB.\u003c/p\u003e \u003cp\u003eTaken together, these findings indicate that the NS-RYGB may have beneficial effects on the postoperative complication rate. However, further investigations are needed to determine whether proportional limb length selection can reliably reproduce these improved postoperative outcomes and reduced complication rates.\u003c/p\u003e \u003cp\u003eFurthermore, the operation time in the NS-RYGB group was on average 12 minutes longer than that in the S-RYGB group. This may be attributed to the time needed for the intraoperative measurement of the SBL and the adaptation of the AL and BPL lengths. This finding is in line with the findings of Soong et al., who found that measuring the total SBL to ensure that the length of the CC remained above 400 cm significantly prolonged the operation time [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Although an increase of operation time is not uncommon when implementing an individualized surgical approach, it raises questions regarding the feasibility and whether this aspect of the NS-RYGB might pose barriers to wider adoption of this procedure, particularly in high-volume centers where operating room efficiency is critical. However, considering that we observed no increase of postoperative complications and identified significantly better outcomes in terms of aHT and T2DM resolution, higher QoL and satisfaction with body weight, and lower rates of iron deficiency one year after NS-RYGB, the longer operation time may not represent a major contraindication to the implementation of this technique. Further investigation is needed to determine whether these clinical benefits can be reproduced more broadly and sustained in the long term.\u003c/p\u003e \u003cp\u003eOne strength of this study is that it is one of the first studies to provide evidence regarding the optimization of RYGB in relation to the SBL, in which equal BPL and AL lengths are selected based on the total SBL, resulting into a proportional CC length. Furthermore, the group size appears to be sufficient, as 242 patients provide sufficient statistical power to attribute weight loss, changes in QoL and changes in comorbidities to the optimized procedure.\u003c/p\u003e \u003cp\u003eHowever, there are several limitations of the study. The patients were not randomly divided into groups; instead, the preferred procedure at our institution was changed to NS-RYGB and a retrospective data analysis was conducted. Although our study design limits the ability to control for all confounders, the comparable baseline characteristics of the two groups reduce the possibility that group differences were caused by selection bias. Additionally, comparisons with other studies were complicated due to a lack of standardization regarding the definition of limb length in the literature, as some studies refer to \u0026ldquo;short\u0026rdquo; limbs and other to \u0026ldquo;long\u0026rdquo; limbs, but these terms are used inconsistently in the literature. Moreover, we collected data for only the first postoperative year, preventing us from drawing long-term conclusions; ideally, the same parameters should be reassessed at 3-year and 5-year follow-up examinations. We are currently conducting these follow-up analyses in this same patient cohort, which will allow us to determine whether the observed effects can be reproduced on a broader scale and maintain in the long term.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eCompared with S-RYGB, NS-RYGB - where equal BPL and AL lengths are selected based on the total SBL, resulting into a proportional CC length - leads to significantly better outcomes in terms of QoL, resolution of aHT and T2DM, satisfaction with body weight and iron deficiency, while achieving a similar reduction in BMI. These findings support a more individualized approach and suggest that incorporating proportional limb length selection into RYGB may improve metabolic and QoL-related outcomes. Further long-term studies are needed to confirm these clinical benefits and to determine whether this approach can refine bariatric surgical practice by enhancing long-term metabolic and QoL outcomes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompliance with ethical standards\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflicts of interest.\u003c/p\u003e\n\u003cp\u003eThe authors declare that all procedures involving human patients were conducted in accordance with the Declaration of Helsinki and that all procedures were carried out with the adequate understanding and written informed consent of all patients.\u003c/p\u003e\n\u003cp\u003eEthical approval was not needed for this retrospective study, as only preexisting, deidentified data from the Quality Assurance Registry of the German Society for General and Visceral Surgery (StuDoQ, DGAV) database were analyzed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003einterest statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthor 1 declares that she has no\u0026nbsp;conflicts\u0026nbsp;of interest.\u003c/p\u003e\n\u003cp\u003eAuthor 2 declares that he has no\u0026nbsp;conflicts\u0026nbsp;of interest.\u003c/p\u003e\n\u003cp\u003eAuthor 3 declares that she has no\u0026nbsp;conflicts\u0026nbsp;of interest.\u003c/p\u003e\n\u003cp\u003eAuthor 4 declares that she has no\u0026nbsp;conflicts\u0026nbsp;of interest.\u003c/p\u003e\n\u003cp\u003eAuthor 5 declares that she has no\u0026nbsp;conflicts\u0026nbsp;of interest.\u003c/p\u003e\n\u003cp\u003eAuthor 6 declares that she has no\u0026nbsp;conflicts\u0026nbsp;of interest.\u003c/p\u003e\n\u003cp\u003eAuthor 7 declares that he has no\u0026nbsp;conflicts\u0026nbsp;of interest.\u003c/p\u003e\n\u003cp\u003eAuthor 8 declares that he has no\u0026nbsp;conflicts\u0026nbsp;of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Sources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe raw data supporting the conclusions of this article are available from the authors.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eLuise Eva K\u0026ouml;hler contributed to the study design, data acquisition, and drafting of the manuscript.Hinrich K\u0026ouml;hler contributed to the study design, data acquisition, and drafting of the manuscript.Ulrich Stefenelli contributed to the statistical analysis and the drafting of the manuscript.Franziska Nieter contributed to the data acquisition.Ioana-Andreea Bollenbach contributed to the drafting of the manuscript.Resa Puffert contributed to the drafting of the manuscript.Clara B\u0026ouml;ker contributed to the critical revision of the manuscript.Julian W Mall contributed to the concept of the study design, drafting of the manuscript and critical revision of the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe raw data supporting the conclusions of this article are available from the authors.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003e- Angrisani L, Santonicola A, Iovino P, et al. 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PMID: 31558409.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 7 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"obesity-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"obsu","sideBox":"Learn more about [Obesity Surgery](https://link.springer.com/journal/11695)","snPcode":"11695","submissionUrl":"https://submission.springernature.com/new-submission/11695/3","title":"Obesity Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8464981/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8464981/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Objective: Roux-en-Y gastric bypass (RYGB) does not account for individual variations in total small bowel length (SBL), which may contribute to variability in outcomes. This study aimed to determine whether postoperative outcomes differ between patients undergoing RYGB with equal BPL and AL lengths, adjusted to the total SBL, resulting in a proportional CC length (NS-RYGB), and patients undergoing standard RYGB (S-RYGB).\nMethods: In July 2021, our institution switched from performing S-RYGB to new standard RYGB technique (NS-RYGB). In NS-RYGB, the total SBL was measured intraoperatively and equal BPL and AL lenghts were selected, depending on the total SBL, resulting in a proportional CC length. We retrospectively analyzed preoperative and one-year postoperative data from 242 patients, including BMI, resolution of comorbidities, quality of life (QoL), satisfaction with body weight and postoperative iron deficiency.\nResults: QoL and satisfaction with body weight were significantly higher in the NS-RYGB group one year after surgery. Resolution of arterial hypertension (aHT) and Type-II-diabetes mellitus (T2DM) occured in a significantly greater percentage of NS-RYGB patients. Grade II and III iron deficiency, postoperative complications and hospital readmissions were significantly less frequently in the NS-RYGB group. Mean postoperative weight loss was comparable between the groups.\nConclusion: NS-RYGB results in better QoL, higher resolution of aHT and T2DM, greater satisfaction with body weight and less iron deficiency, while achieving similar weight loss. These findings support proportional limb length selection as a promising approach. Further long-term studies are needed to confirm these clinical benefits.","manuscriptTitle":"Small bowel length in RYGB: Does limb length matter? Questions remain; Adapting the biliopancreatic and alimentary limb lengths to the total small bowel length in RYGB leads to better postoperative outcomes, such as quality of life, satisfaction with body weight, resolution of comorbidities and iron deficiency","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-13 17:55:18","doi":"10.21203/rs.3.rs-8464981/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-02T14:52:27+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-27T08:03:50+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-26T13:35:38+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-23T19:10:00+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-22T11:42:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"182967575436970290924922445932119850874","date":"2026-02-21T07:52:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"170270996273843308465003051003004634482","date":"2026-02-20T17:47:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"206043924747016169182306221210643997292","date":"2026-02-20T14:23:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"101769873444679627065363155531069495502","date":"2026-02-20T06:31:10+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-10T02:48:00+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-05T16:10:58+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-03T00:39:15+00:00","index":"","fulltext":""},{"type":"submitted","content":"Obesity Surgery","date":"2025-12-28T09:21:46+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"obesity-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"obsu","sideBox":"Learn more about [Obesity Surgery](https://link.springer.com/journal/11695)","snPcode":"11695","submissionUrl":"https://submission.springernature.com/new-submission/11695/3","title":"Obesity Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"fb76c7f1-ce1e-49ca-88ff-3a54349a722a","owner":[],"postedDate":"February 13th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-11T11:45:44+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-13 17:55:18","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8464981","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8464981","identity":"rs-8464981","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}