Effects of Minimally Invasive Gynecologic Surgery Subspecialty Training on Outcomes of Hysterectomy for Benign Indications.

This was a retrospective cohort study that included all patients who underwent hysterectomy for benign indications between March 2015 and March 2020 within a Department of Obstetrics and Gynecology at a quaternary care academic hospital. Study approval was granted by the Cedars Sinai Medical Center IRB (#3352, March 28, 2024). We included patients who underwent any type of hysterectomy performed for benign indications during the study period by minimally invasive gynecologic surgeons (MIGS group), ob-gyns (OB-GYN group), and gynecologic oncologists (GO group). Gynecologic oncologist surgeons were included as a second reference group, because gynecologic oncologists at our institution perform a large number of benign surgical procedures and receive referrals from community practices for hysterectomy with benign indications. This reference group can serve to further isolate the effect of fellowship from the surgical volume aspect. Exclusion criteria were malignant or premalignant condition, pelvic mass (other than leiomyoma), concomitant correction of pelvic organ prolapse, and peripartum hysterectomy. Cases with malignancy suspected preoperatively were also excluded, because this can change the conversion to laparotomy rate. Data were collected from the electronic medical record. Baseline patient characteristics included age, body mass index (BMI, calculated as weight in kilograms divided by height in meters squared), American Society of Anesthesiologists classification, race, ethnicity, parity, preoperative anemia (defined as hemoglobin value less than 11 g/dL), prior laparotomies, and insurance type. Operative characteristics included surgical indications, surgical approach (conventional laparoscopy, robotic-assisted laparoscopy, abdominal, vaginal), hysterectomy type (total, supracervical), specimen weight, presence of deeply infiltrating endometriosis, EBL, total surgery time, total admission time, and same-day discharge. Surgical approach was classified into minimally invasive versus laparotomy. Minimally invasive hysterectomy was defined as any laparoscopic, robotic, or vaginal hysterectomies. Perioperative complications included intraoperative and postoperative complications within 30 days of surgery. Surgeons performing the surgery were classified into three categories according to their training: general ob-gyns, fellowship-trained gynecologic oncologists, and fellowship-trained minimally invasive gynecologic surgeons. We further collected data on surgeons' hysterectomy volume, calculated by surgeons' average number of hysterectomies performed annually. Compared with White patients, patients in minoritized groups previously have been found to have lower access to MIH, undergo more abdominal hysterectomies, and have increased risk of perioperative complications. 12 – 16 Therefore, we included race and ethnicity to provide information on the cohort's demographics and because we hypothesized that it might affect outcomes. Intraoperative complications were classified using the Classification of Intraoperative Complications scale, 17 and postoperative complications were classified using the Clavien-Dindo scale. 18 Both scales are widely accepted methods for grading and categorizing surgical complications based on severity and the interventions required to manage them. The classification systems provide a standardized framework for comparing complication rates across different surgical procedures and institutions. Intraoperative and postoperative complications were further classified into minor and major. For both intraoperative and postoperative scales, grades 1 and 2 were minor complications and grades 3–5 were major complications. Intraoperative complications included any of the following: bladder, bowel or ureteral injury, excessive intraoperative bleeding, blood transfusion, and other rare complications. Postoperative complications included infections (pelvic abscess, superficial surgical site infection, urinary tract infection), urinary retention, bleeding or hematoma, blood transfusion, ileus or small bowel obstruction, ureteral or bowel injury diagnosed postoperatively, vaginal cuff cellulitis or dehiscence, deep vein thrombosis, pulmonary embolism, cardiac complication, readmission, reoperation, mortality, and other rare complications. An intention-to-treat approach was adapted for the analysis. In cases where MIH, was planned and the final surgical approach was abdominal hysterectomy, the case was classified as MIH converted to laparotomy. We compared surgical outcomes among the three surgeon groups. The primary outcome was the odds of a composite of any intraoperative or postoperative complications by surgeon group. Secondary outcomes included conversion to laparotomy rates, EBL, and admission times by surgeon subspecialty. We hypothesized that the odds of experiencing the primary outcomes would be lower among minimally invasive gynecologic surgeons compared with the other two surgeon types. We compared ob-gyn, gynecologic oncology, and minimally invasive gynecologic surgeons. For categorical variables, we used chi-square and Fisher exact tests, as appropriate. When statistical significance was reached, we used the pairwise comparison of proportions using the Bonferroni correction to identify which pairs of groups differed significantly. For continuous variables we used the Kruskal-Wallis test. When statistical significance was reached, we used the post hoc Dunn test to identify which pairs of groups differed significantly. Categorical variables were reported as proportions and continuous variables as median (interquartile range). For the conversion to laparotomy outcome, the denominator excluded cases that were scheduled as abdominal hysterectomy. Multivariable logistic regression analyses were performed to identify variables independently associated with the primary and secondary outcomes. The multivariable logistic regression analysis models included factors that reached statistically significant difference in the univariate analysis and are clinically relevant. Results were reported as adjusted odds ratio (aOR) and 95% CI. Two-sided P <.05 was considered statistically significant. As this is a retrospective study, we performed a post hoc power analysis, considering the variables included in the multivariable regression analysis. For four variables, with a probability level of 0.05, a statistical power of 0.8 will be obtained to detect an odds ratio of 1.114 with 202 patients, and 1.075 with 301 patients. Based on the study's sample size, the power was sufficient for the primary outcome. Statistical analyses were performed using SPSS 27 and R. Sample size calculation was performed using the A-priori Sample Size Calculator for Multiple Regression. 19

A total of 946 hysterectomies were performed during the study period; 356 (37.6%) were performed by general ob-gyns, 220 (23.3%) by gynecologic oncologists, and 370 (39.1%) by minimally invasive gynecologic surgeons. Hysterectomies were performed by 34 general ob-gyns, seven gynecologic oncologists, and four minimally invasive gynecologic surgeons. Abdominal hysterectomies were performed in 36.8% of cases in the OB-GYN group and 30.0% of cases in the GO group, compared with 0.3% of cases in the MIGS group ( P <.001). Patient characteristics are presented in Table 1 . The following variables differed significantly among groups: age, BMI, race, parity, and insurance type. American Society of Anesthesiologists classification, ethnicity, preoperative anemia, and prior laparotomies were comparable among groups. Surgical characteristics are presented in Table 2 . Uterine leiomyomas were more often the surgical indication in the OB-GYN and MIGS groups compared with the GO group ( P <.001); endometriosis, adenomyosis and pelvic pain were more often the surgical indication in the MIGS group ( P <.001). Uterine weights were higher in the OB-GYN and MIGS groups compared with the GO group ( P <.001). Obstetrician–gynecologists asked for assistance from subspecialists in 34 cases (9.6%)—23 from minimally invasive gynecologic surgeons and 11 from gynecologic oncology surgeons. Gynecologic oncologists asked for assistance from minimally invasive gynecologic surgeons in three cases (1.4%), and minimally invasive gynecologic surgeons asked for assistance from a gynecologic oncologist in one case (0.3%, P <.001). Estimated blood loss, total admission time from surgery to discharge, and total days of hospitalization were all lower in the MIGS group compared with the other two groups ( P <.001 for all comparisons). Total surgery time was longer for the OB-GYN and MIGS groups compared with the GO group ( P <.001). The rate of same-day discharge was significantly higher in the MIGS group compared with the other two groups ( P <.001). Patient Demographic and Clinical Characteristics, Stratified by Surgeon Type Ob-Gyn, obstetrician–gynecologist; MIGS, minimally invasive gynecologic surgery; BMI, body mass index; ASA, American Society of Anesthesiology; Hb, hemoglobin; PPO, preferred provider organization; HMO, health maintenance organization. Data are median (interquartile range) or n (%) unless otherwise specified. Statistically significant difference ( P <.05) between gynecologic oncology and MIGS. Statistically significant difference ( P <.05) between general ob-gyn and gynecologic oncology. Statistically significant difference ( P <.05) between general ob-gyn and MIGS. ASA classifications 3 and 4 were collapsed into a single category because only two patients in the cohort had classification 4. Operative Characteristics, Stratified by Surgeon Type Ob-Gyn, obstetrician–gynecologist; MIGS, minimally invasive gynecologic surgery; EBL, estimated blood loss. Data are n (%) or median (interquartile range) unless otherwise specified. Surgeries could have more than one indication. Statistically significant difference ( P <.05) between the general ob-gyn and gynecologic oncology (GO) groups. Statistically significant difference ( P <.05) between the GO and MIGS groups. Statistically significant difference ( P <.05) between general ob-gyn and MIGS groups. Twenty-three were MIGS-assisted, and 11 were gynecologic oncologist–assisted. Minimally invasive gynecologic surgeon assistance. Gynecologic oncology assistance. Surgical outcomes are presented in Table 3 . The composite of any intraoperative or postoperative complications was significantly lower in the MIGS group compared with the OB-GYN group ( P =.005), as was any intraoperative or postoperative minor complications ( P =.009). Of 34 general ob-gyns, 20 (58.8%) experienced complications; all gynecologic oncologists and minimally invasive gynecologic surgeons experienced complications. The rate of conversion to laparotomy was higher in the OB-GYN and GO groups (7.6% and 7.1% respectively) compared with the MIGS group (0.3%, P <.001). Any postoperative and minor postoperative complications occurred more often in the OB-GYN group compared with the MIGS group ( P =.018 and P =.024 respectively). Detailed outcomes with specific complications are presented in Appendix 1, available online at http://links.lww.com/AOG/D910 . Rates of Perioperative Complications, Stratified by Surgeon Type Ob-Gyn, obstetrician–gynecologist; MIGS, minimally invasive gynecologic surgery. Data are n (%) unless otherwise specified. Statistically significant difference ( P <.05) between general ob-gyn and MIGS. The denominator excludes cases that were scheduled as abdominal hysterectomy (ie, were not converted after diagnostic laparoscopy). Statistically significant difference ( P <.05) between gynecologic oncology and MIGS. . Multivariable regression analyses of surgical outcomes are presented in Table 4 . The aOR for any intraoperative or postoperative complications was 1.79 (95% CI, 1.14–2.08) in the GO group and 1.64 (95% CI, 1.01–2.69) in the OB-GYN group compared with the MIGS group. The unadjusted odds ratios for conversion to laparotomy were 28.31 (95% CI, 3.62–221.26) in the GO group and 30.08 (95% CI, 3.97–227.63) for in the OB-GYN group compared with the MIGS group. No adjustment could be performed given only one conversion in the MIGS group. The aOR (95% CI) for same-day discharge was independently lower in the GO group (0.50, 0.29–0.86) and the OB-GYN group (0.23, 0.15–0.33) compared with the MIGS group. Multivariable Regression Analysis of Surgical Outcomes by Surgeon Type MIGS, minimally invasive gynecologic surgery; Ob-Gyn, obstetrics and gynecology. Data are adjusted odds ratio (95% CI). Adjusted for body mass index (BMI), surgical approach, and uterine weight. Unadjusted due to small number of conversions (n=29). Adjusted for BMI, American Society of Anesthesiology classification 3–4, surgical indication (endometriosis, adenomyosis, and pelvic pain), uterine weight, and surgical approach.

In this cohort of patients undergoing hysterectomy, the rate of MIH was significantly higher for minimally invasive gynecologic surgeons and the rates of complications were lower compared with gynecologic oncologists and ob-gyns. Minimally invasive gynecologic surgery cases were associated with less blood loss, fewer conversions to laparotomy, shorter admission time, and higher rates of same-day discharge compared with the reference groups. The association between fellowship training and surgical outcomes is well documented in the general surgery literature. In a systematic review and meta-analysis of general surgery studies, fellowship training was associated with fewer surgical complications, fewer conversions, and decreased mortality. 20 However, in gynecology, and minimally invasive gynecologic surgery specifically, data are scant. In our study, abdominal hysterectomy was performed in only one case in the MIGS group, compared with approximately a third of cases in the two other groups. In a study by Shirreff et al, 11 laparoscopic hysterectomy was performed in 80.7% of cases in the MIGS group compared with 50.0% of cases in the OB-GYN group. During fellowship, minimally invasive gynecologic surgery trainees are exposed to complex benign cases and learn how to manage them in a reproducible manner. The gynecologic oncology fellowship focuses on malignancy cases, potentially leading to heightened concern for malignancy even in cases with benign features such as very large leiomyomas or severe endometriosis. 21 These core differences between the study groups may explain the different proportions of laparotomies performed. The risk of complications was independently associated with the minimally invasive gynecologic surgery subspecialty compared with the two other groups. The risk of perioperative complications was similar in the two previously mentioned studies that compared minimally invasive gynecologic surgeons and ob-gyns. 10 , 11 Regarding conversions to laparotomy, a study by Clark et al 10 reported conversions and found a trend of fewer complications in minimally invasive gynecologic surgery cases, but it was limited by sample size and did not adjust for potential confounders. Another study on MIH found lower conversion rates among gynecologic subspecialists compared with ob-gyns, but did not stratify the types of subspecialties. 2 Although uterine sizes were comparable in surgeries performed by ob-gyn and minimally invasive gynecologic surgery subspecialists, they were larger than those in surgeries performed by gynecologic oncologists. Taken together, these studies and ours suggest that complications and conversions to laparotomy can be minimized when procedures are performed by minimally invasive gynecologic surgeons who are experienced with approaching very large and complex benign pathology with a minimally invasive approach. Discharge after minimally invasive surgery is faster compared with laparotomy and explains the differences found in the univariate analysis regarding length of stay. 22 However, this finding persisted after adjusting for confounders including surgical approach and comorbidities, and is comparable with a previous study on MIH. 10 Of note, the minimally invasive gynecologic surgery division at our institution implemented enhanced recovery after surgery guidelines in August of 2018. These guidelines have not been implemented uniformly in other divisions. Earlier discharge times in the MIGS group may therefore be partially explained by these differences. The proportion of Black or African American patients was higher in the OB-GYN group compared with the other groups. It has been previously shown that individuals in minoritized groups are less likely to be referred to subspecialists, less likely to undergo minimally invasive surgery, and experience lower private insurance coverage compared with White patients, in line with our findings. 23 – 26 These barriers should be addressed to provide equitable health care to all races and ethnicities. Of note, although there was statistical difference in the proportion of Black or African American patients among subspecialists groups, we found no association between race and complications. Therefore, race was not input in the multivariable regression analyses. The main strength of this study is the evaluation of the effect of minimally invasive gynecologic surgery training on surgical outcomes, with only a few prior studies reporting similar comparisons. Another strength is the comparison of minimally invasive gynecologic surgery with two other groups, allowing analysis of the effect of postgraduate training and experience. Specifically, the comparison with the GO group underlines the independent association between fellowship training and outcomes, especially given the comparable hysterectomy volumes for minimally invasive gynecologic surgery and gynecologic oncology subspecialists (Appendix 2, available online at http://links.lww.com/AOG/D910 ). A main limitation of this study is its retrospective design with inherent biases and potential factors that were not assessed (eg, preoperative imaging quality, surgical instruments used, postoperative visits at community practices outside our hospital system). In addition, the generalizability of the results is limited by the single-center design. Our medical center is a quaternary academic hospital, with a relatively high proportion of highly trained surgeons, and with referral patterns that can differ from other medical centers, further limiting the generalizability of the results. We did not evaluate outcomes by each surgeon, rather as subspecialty groups. Because a correlation between specific surgeons and outcomes is likely, this may limit the inference that can be drawn from the results. Furthermore, we used uterine weight as a factor in the regression models, as a surrogate of uterine size. Preoperative uterine size evaluation may be more clinically relevant, because uterine weight is known only postoperatively. Additionally, some of the ob-gyns practicing in our institution operate in other medical centers; thus, the surgical volume presented for this group may be an underestimation. However, the low number of average annual hysterectomies performed by general ob-gyns should still be acknowledged as a major limitation of this study. Finally, the sample size did not allow for measurement of specific outcomes. The results of this study underline the effect of minimally invasive gynecologic surgery fellowship training on patient outcomes in hysterectomy for benign indications and can assist in patient referrals, preoperative planning, and patient expectations.