Robotic assisted versus conventional laparoscopic ovarian suture reapproximation in ovarian cystectomy of ovarian endometriomas in preserving ovarian reserve

Patient data were extracted from electronic medical records within the timeframe of February 1, 2017, to December 31, 2023, using the keyword “ovarian endometriosis.” A total of 259 patient records were retrieved. Inclusion criteria: (1). Age > 18 years; (2). Underwent surgical treatment, specifically laparoscopy or the Da Vinci robotic system; (3). Postoperative histopathological confirmation of ovarian endometriosis; (4). Presence of an OMA larger than 4 cm in diameter. Exclusion criteria: Exclusion criteria: (1) Incomplete general patient information; (2) History of ovarian surgery or hormone treatment within six months prior to surgery; (3) Other surgeries performed during the operation besides excision of ovarian endometriotic cysts, such as myomectomy, salpingectomy, etc.; (4) Incomplete postoperative follow-up data; (5) Presence of severe systemic diseases, such as malignant tumors, serious disorders of the heart, liver, kidney, hematologic, endocrine systems, or autoimmune diseases. Ultimately, 154 patients were included in the study, with 85 in the laparoscopy group and 69 in the Da Vinci robotic group (Supplemental Fig. 1). All procedures were conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Jeonbuk National University, Korea (Approval No. 2024-08-037-004). Written informed consent was obtained from all participants prior to inclusion. All CL and ROS-RAL OMA surgeries were performed under general anesthesia by the same gynecologic surgeon, H.S. Chae, with assistance from C. Lin. Using a Veress needle, a pneumoperitoneum was established through a 10 mm vertical incision below the umbilicus, followed by the insertion of a 10 mm laparoscope. Two additional 5 mm trocars were placed to insert auxiliary instruments. After performing ovarian adhesion dissection, the endometriotic cyst was opened, and its contents were aspirated. Once the cleavage plane between the normal ovarian tissue and the cyst wall was identified, the cyst wall was separated from the ovarian parenchyma using atraumatic forceps and counter-traction. If the cleavage plane was unclear, scissors were used to trim the cyst wall. After cyst excision, the subsequent surgical steps can be divided into two types based on whether bipolar electrocoagulation is applied to the bleeding site. One approach involves achieving hemostasis with electrocoagulation before suturing, while the other completely avoids electrocoagulation and achieves hemostasis solely through ovarian suturing. The sutures were applied from the ovarian surface to the vicinity of the mesovarium to ensure effective hemostasis (Fig.  1 ). Fig. 1 Schematic diagram of the procedure for CL OMA surgery: expose the cyst and make a longitudinal incision along the free side of the ovary, cutting through the ovarian cortex to the cyst wall. Aspirate the cyst fluid, and use dissecting forceps to bluntly separate the boundary between the cyst wall and the ovarian cortex. Completely peel off the cyst wall and hemostasis can be divided into two types: One approach involves achieving hemostasis with electrocoagulation before suturing, while the other completely avoids electrocoagulation and achieves hemostasis solely through ovarian suturing. The suturing involved the full thickness of the ovarian cortex and the medulla, including both the inner and outer cortical layers, and was performed using interrupted figure-of-eight stitches Schematic diagram of the procedure for CL OMA surgery: expose the cyst and make a longitudinal incision along the free side of the ovary, cutting through the ovarian cortex to the cyst wall. Aspirate the cyst fluid, and use dissecting forceps to bluntly separate the boundary between the cyst wall and the ovarian cortex. Completely peel off the cyst wall and hemostasis can be divided into two types: One approach involves achieving hemostasis with electrocoagulation before suturing, while the other completely avoids electrocoagulation and achieves hemostasis solely through ovarian suturing. The suturing involved the full thickness of the ovarian cortex and the medulla, including both the inner and outer cortical layers, and was performed using interrupted figure-of-eight stitches After making a 12 mm transverse subumbilical incision, a camera port was inserted through the incision to create pneumoperitoneum. Then two 8 mm da Vinci ports were placed in the left and right lower quadrants of abdomen, respectively. A 12 mm trocar as an assistant port was placed between camera port and left da Vinci port. An incision is made on the cyst and the contents of OMA were suctioned. Adhesions between OMA and surrounding structures were lysed to expose the ovary. The cleavage plane between the normal ovarian tissue and the capsule of OMA was identified. Then, OMA were removed by stripping the capsule of the cyst from the normal ovarian tissue using traction and countertraction forces. Then, only the stroma was closed, without penetrating the cortex, thereby minimizing mechanical injury to functional ovarian tissue. The reconstruction was completed using interrupted figure-of-eight sutures. In most cases, the edge of the ovarian incision was left unsutured. However, sometimes, only the edges of the ovarian incision were sutured to close the ovary in order to maintain its shape (Fig.  2 ). All sutures used were 3 − 0 polyglactin 910 (Vicryl ® , Ethicon Ltd., Edinburgh, UK). Fig. 2 Schematic diagram of ROS-RAL suturing the OMA: The cyst removal process is performed similarly to CL techniques. During suturing, absorbable sutures are inserted into the ovarian stroma, passed through the bleeding deep tissues, and exited through the stroma on the opposite side. This process is repeated, and the sutures are tightened to form an “X” shape. A knot is tied at the crossing point. The sutures do not pass through the ovarian surface cortex, and hemostasis is achieved by intermittently suturing only the ovarian stroma. Postoperatively, the edge of the ovarian incision was left unsutured. In most cases, the ovarian incision was left unsutured; however, to preserve the ovarian shape, sutures may occasionally be applied starting from the edges of the incision, with hemostasis performed as described above Schematic diagram of ROS-RAL suturing the OMA: The cyst removal process is performed similarly to CL techniques. During suturing, absorbable sutures are inserted into the ovarian stroma, passed through the bleeding deep tissues, and exited through the stroma on the opposite side. This process is repeated, and the sutures are tightened to form an “X” shape. A knot is tied at the crossing point. The sutures do not pass through the ovarian surface cortex, and hemostasis is achieved by intermittently suturing only the ovarian stroma. Postoperatively, the edge of the ovarian incision was left unsutured. In most cases, the ovarian incision was left unsutured; however, to preserve the ovarian shape, sutures may occasionally be applied starting from the edges of the incision, with hemostasis performed as described above Preoperative data recorded included patient age, body mass index (BMI), cyst size, cyst number, laterality, serum cancer antigen (CA) 125 levels. Endometriosis was classified according to the revised American Society for Reproductive Medicine (rASRM) classification [ 16 ]. The size of the cyst was determined as the average of the sum of the long and transverse axes of the cyst, and in the case of bilateral cysts, it was determined as the sum of the sizes of the cysts on both sides. The number of cysts is referenced from the operative records, but in the case of laparoscopy, there are cases where it is not recorded, and in these cases, the number of cysts was determined based on magnetic resonance imaging. The total operation time was defined as the time from skin incision to closure. Serum hemoglobin (Hb) levels were measured preoperatively and on the 1st days postoperatively. Anti-Müllerian hormone (AMH) levels were measured preoperatively and at 1, 6, 12, 24, and 36 months postoperatively. The serum AMH level was determined using a commercial kit (AMH Gen II assay; Beckman Coulter Inc., USA) and the result was recorded in ng/ml. The changes and decline rates in AMH levels (ΔAMH%) at each postoperative time point were documented, as well as the incidence of diminished ovarian reserve (DOR). ΔAMH% was calculated using the formula: 100 x (preoperative AMH - postoperative AMH) / preoperative AMH. According to the Bologna criteria, DOR was defined as AMH < 1.1 ng/ml [ 28 ]. Continuous variables following a normal distribution were expressed as mean ± standard deviation (χ ± s) and compared using an independent samples t-test. Categorical variables were expressed as percentages or frequencies and compared using Pearson’s chi-squared test. Univariate and multivariate analyses were conducted using binary logistic regression models, with odds ratios (OR) and 95% confidence intervals (CI) calculated. Statistical analyses were performed using SPSS version 22.0. All hypothesis tests were two-sided, with a significance level set at p  < 0.05.

A total of 154 patients were included in this study, with 85 undergoing CL surgery and 69 undergoing RAL surgery (Table  1 ). There were no significant differences between the two groups in terms of age (CL: 30.13 ± 6.15 vs. RAL: 29.38 ± 6.26, p  = 0.457) and BMI (CL: 21.45 ± 2.80 vs. RAL: 21.50 ± 2.73, p  = 0.689). However, the RAL group had significantly larger cyst sizes (7.25 ± 3.47 vs. 6.19 ± 2.28, p  = 0.024) and a higher number of cysts (3.90 ± 2.60 vs. 2.40 ± 1.42, p  < 0.001) compared to the CL group. Additionally, the proportion of bilateral cases was higher in the RAL group (50.72% vs. 31.76%, p  = 0.017), and most patients in this group were at stage IV of endometriosis (84.06% vs. 62.35%, p  = 0.003). The rASRM score was also significantly higher in the RAL group (75.29 ± 35.37 vs. 57.09 ± 35.54, p  = 0.002). There were no significant differences between the two groups in CA 125 levels, duration of surgery, and hemoglobin decline. Table 1 Baseline characteristics of CL group versus the RAL group Total CL RAL p N  = 154 N  = 85 N  = 69 Age, years 29.79 ± 6.19 30.13 ± 6.15 29.38 ± 6.26 0.457 BMI, kg/m 2 21.56 ± 3.09 21.45 ± 2.80 21.50 ± 2.73 0.689 Cyst size, cm 6.67 ± 2.92 6.19 ± 2.28 7.25 ± 3.47 0.024 Cyst number 3.07 ± 2.16 2.40 ± 1.42 3.90 ± 2.60 < 0.001 Laterality , n (%) 0.017 Unilateral 92 (59.74) 58 (68.24) 34 (49.28) Bilateral 62 (40.26) 27 (31.76) 35 (50.72) CA 125, U/ml 65.22 ± 136.8 52.07 ± 62.84 81.43 ± 191.71 0.186 Endometriosis stage , N (%) 0.003 III 43 (27.92) 32 (37.65) 11 (15.94) IV 111 (72.08) 53 (62.35) 58 (84.06) r ASRM score 65.25 ± 36.50 57.09 ± 35.54 75.29 ± 35.37 0.002 Duration of operation, min 91.71 ± 36.21 89.19 ± 32.67 94.81 ± 40.17 0.339 Hb loss, g/dl 1.63 ± 0.80 1.57 ± 0.84 1.70 ± 0.76 0.315 BMI: body mass index, CA125: cancer antigen 125, CL: conventional laparoscopy, Hb: Hemoglobin, RAL: robot-assisted laparoscopy, r-ASRM score: revised American Society for Reproductive Medicine score Baseline characteristics of CL group versus the RAL group BMI: body mass index, CA125: cancer antigen 125, CL: conventional laparoscopy, Hb: Hemoglobin, RAL: robot-assisted laparoscopy, r-ASRM score: revised American Society for Reproductive Medicine score The intraoperative images demonstrate notable differences in the ovarian presentation between the CL and RAL groups. Supplemental Fig. 2A depicts the typical intraoperative findings of CL OMA surgery. Following cyst excisionconventional suturing techniques are employed to perform full-thickness suturing of both the ovarian cortex and stroma. Bluish discoloration observed in portions of the surgical-side ovary suggests potential ischemic injury. In contrast, Supplemental Fig. 2B illustrates the intraoperative findings during RAL surgery. The innovative ROS suturing technique eliminates the need for suturing the ovarian cortex, selectively targets the vascular-rich ovarian stroma, effectively reducing the mechanical stress exerted on ovarian tissue by sutures. This approach not only improves ovarian perfusion, but also allows tissue suturing to be performed more easily and with greater precision and control compared with conventional laparoscopic suturing, owing to the enhanced dexterity provided by the robotic system, thereby improving operative efficiency. Notably, Supplemental Fig. 2-B3 reveals that the surgical-side ovary in the ROS-RAL group exhibits coloration consistent with the non-operated contralateral ovary, indicating that ovarian perfusion has been well preserved. At this time, the edges of the ovarian incision were sutured to close the ovary. Supplemental Fig. 2-B3 shows that the surgical-side ovary in the ROS-RAL group demonstrates no discoloration compared with the non-operated contralateral ovary, indicating that ovarian perfusion has been well preserved. Preoperative AMH levels showed no significant difference between the two groups (CL: 3.68 ± 2.69 ng/ml, RAL: 3.78 ± 2.43 ng/ml, p  = 0.817). However, at 1 month postoperatively, the AMH levels in the RAL were higher than those in the CL group (2.78 ± 1.91 vs. 2.20 ± 1.70 ng/ml, p  = 0.047). This significant difference persisted at 12 months (2.62 ± 1.82 vs. 2.06 ± 1.59 ng/ml, p  = 0.043) and 36 months (2.27 ± 1.64 vs. 1.66 ± 1.50 ng/ml, p  = 0.018) postoperatively (Table  2 , Supplemental Fig. 3A). Regarding the decline rates in AMH levels, the RAL group had lower rates at all measured time points: 1 month (17.40 ± 36.00% vs. 40.76 ± 26.95%, p  < 0.001), 6 months (19.74 ± 40.09% vs. 43.08 ± 34.85%, p  < 0.001), 12 months (21.68 ± 38.79% vs. 43.35 ± 28.58%, p  < 0.001), 24 months (24.08 ± 37.89% vs. 44.00 ± 28.88%, p  < 0.001), and 36 months (30.43 ± 37.30% vs. 48.27 ± 35.76%, p  < 0.001) (Table  2 , Supplemental Fig. 3B). Table 2 AMH levels and AMH decline rate between CL group and RAL group CL RAL p AMH , ng/ml Pre-operation 3.68 ± 2.69 3.78 ± 2.43 0.817 1 month 2.20 ± 1.70 2.78 ± 1.91 0.047 6 months 2.07 ± 1.43 2.53 ± 1.58 0.062 12months 2.06 ± 1.59 2.62 ± 1.82 0.043 24 months 2.00 ± 1.51 2.48 ± 1.69 0.065 36 months 1.66 ± 1.50 2.27 ± 1.64 0.018 Δ AMH , % 1 month 40.76 ± 26.95 17.40 ± 36.00 < 0.001 6 months 43.08 ± 34.85 19.74 ± 40.09 < 0.001 12 months 43.35 ± 28.58 21.68 ± 38.79 < 0.001 24 months 44.00 ± 28.88 24.08 ± 37.89 < 0.001 36 months 48.27 ± 35.76 30.43 ± 37.30 < 0.001 AMH: anti-Müllerian hormone, CL: conventional laparoscopy, RAL: robot-assisted laparoscopy AMH levels and AMH decline rate between CL group and RAL group AMH: anti-Müllerian hormone, CL: conventional laparoscopy, RAL: robot-assisted laparoscopy There was no significant difference in the preoperative incidence of DOR between the CL group and the RAL group (CL: 12.94%, RAL: 14.49%, p  = 0.780). At 1 month postoperatively, the incidence of DOR was similar between the two groups (CL: 18.82%, RAL: 18.84%, p  = 0.998). Over time, the incidence of DOR gradually increased in the CL group. By 36 months postoperatively, the incidence of DOR in the CL group was significantly higher than in the RAL group, with this difference being statistically significant (27.54% vs. 44.71%, p  = 0.028) (Table  3 , Supplemental Fig. 3C). Table 3 DOR between CL group and RAL group The incidence of DOR Pre-operation 1 month 6 months 12 months 24 months 36 months CL, n (%) ( n  = 85) 11 (12.94) 16(18.82) 20 (23.53) 23 (27.06) 29 (34.12) 38(44.71) RAL, n (%) ( n  = 69) 10 (14.49) 13 (18.84) 14 (20.29) 16 (23.19) 18 (26.09) 19 (27.54) P 0.780 0.998 0.630 0.583 0.282 0.028 AMH: anti-Müllerian hormone, CL: conventional laparoscopy, DOR: diminished ovarian reserve, RAL: robot-assisted laparoscopy DOR between CL group and RAL group AMH: anti-Müllerian hormone, CL: conventional laparoscopy, DOR: diminished ovarian reserve, RAL: robot-assisted laparoscopy In the univariate and multivariate logistic regression analysis of DOR incidence at 3 years post-surgery between the CL group and the RAL group, several variables were found to be significantly associated with DOR. Univariate analysis revealed that age (OR: 1.20, p  < 0.001), laterality (bilateral, OR: 2.26, p  = 0.017), surgical duration (OR: 1.01, p  = 0.041), RAL surgery (OR: 0.47, p  = 0.029), and preoperative AMH levels (OR: 0.41, p  < 0.001) were associated with DOR. In contrast, variables such as the number and size of ovarian cysts, BMI, CA 125 levels, and endometriosis stage (III and IV) did not show significant associations in the univariate analysis. In the multivariate analysis, younger age (OR: 0.12, 95% CI: 0.08–0.16, p  < 0.001), bilateral cysts (OR: 3.36, 95% CI: 1.24–9.74, p  = 0.020), RAL surgery (OR: 0.207, 95% CI: 0.068–0.561, p  = 0.003), and higher preoperative AMH levels (OR: 0.43, 95% CI: 0.29–0.59, p  < 0.001) remained significantly associated with DOR (Table  4 ). Table 4 The regression analysis of DOR at 36 months after surgery Variable Univariate analysis Multivariate analysis OR (95% CI) p OR (95% CI) p Age 1.20 (1.12, 1.28) < 0.001 -0.12 (-0.16, -0.08), < 0.001 BMI 1.02 (0.92, 1.14) 0.655 NA Cyst size 0.95 (0.85, 1.07) 0.429 NA Cyst number 1.01 (0.86, 1.17) 0.943 NA Laterality Unilateral Ref Ref Bilateral 2.26 (1.15, 4.41) 0.017 3.36 (1.24, 9.74) 0.020 CA 125 0.99 (0.99, 1.00) 0.055 NA Endometriosis stage Ⅲ Ref NA Ⅳ 1.76 (0.82, 3.79) 0.148 NA r ASRM score 1.01 (1.00, 1.02) 0.062 NA Duration of operation 1.01 (1.00, 1.02) 0.041 1.01 (0.997, 1.02) 0.170 Hb loss 0.99 (0.66, 1.48) 0.949 NA Surgical approach CL Ref Ref RAL 0.47 (0.24, 0.93) 0.029 0.207 (0.068, 0.561) 0.003 Pre-operation AMH 0.41 (0.31, 0.56) < 0.001 0.43 (0.29, 0.59) < 0.001 AMH: anti-Müllerian hormone, BMI: body mass index, CA125: cancer antigen 125, CL: conventional laparoscopy, DOR: diminished ovarian reserve, Hb: Hemoglobin, NA: not available, RAL: robot-assisted laparoscopy, r-ASRM score: revised American Society for Reproductive Medicine score, Ref: reference The regression analysis of DOR at 36 months after surgery AMH: anti-Müllerian hormone, BMI: body mass index, CA125: cancer antigen 125, CL: conventional laparoscopy, DOR: diminished ovarian reserve, Hb: Hemoglobin, NA: not available, RAL: robot-assisted laparoscopy, r-ASRM score: revised American Society for Reproductive Medicine score, Ref: reference During a 36-month postoperative follow-up, five patients in the CL group experienced a recurrence of OMA, resulting in a recurrence rate of 5.88%, whereas no cases of recurrence were observed in the RAL group (Supplemental Fig. 3D). The average age of the five patients who experienced recurrence was 29.8 years, and their cysts had an average diameter of 5.5 cm. All five patients received postoperative pharmacological therapy to prevent recurrence; specifically, two patients were prescribed oral dienogest (Visanne ® ), while the remaining three were administered combined oral contraceptives.

ROS-RAL OMA surgery offers significantly favorable long-term outcomes in preserving ovarian function in OMA patients and positively impacts reducing postoperative cyst recurrence. Larger, multicenter studies are recommended to further validate these findings.

Preserving ovarian reserve during OMA surgery remains a significant challenge, whether performed using RAL or CL. Despite the greater precision and flexibility offered by RAL, the preservation of ovarian reserve following RAL-OMA surgery does not differ significantly from that of CL. Growing evidence indicates that both CL and RAL OMA surgeries have significantly negative impacts on ovarian reserve [ 29 , 30 ]. In both surgical methods, hemostasis of the vascular-rich ovarian stroma, from which the OMA is removed, is typically achieved through cauterization prior to suturing or by tightly ligating the incised ovary using the suturing method. While these approaches are effective for achieving hemostasis, they result in ischemic damage to the operated ovary. The cauterization method achieves hemostasis by burning the bleeding vessels, and the burned site inevitably causes ischemic damage, leading to a reduction in ovarian reserve. Studies on OMA surgery repeatedly reported that cauterization method significantly reduces ovarian reserve and function, and can even cause ovarian dysfunction or failure [ 31 , 32 ]. Due to the limitations of ovarian reserve preservation with cauterization method, suturing method, which achieve hemostasis by tightly ligating the bleeding ovary, have been explored. Comparative studies have shown that suture-based hemostatic methods, compared to cauterization method, slightly reduce the impact on ovarian reserve, but the improvement is not significant [ 33 – 36 ]. The limitation of suturing methods lies in ischemic damage to the distal area of the blood vessel due to restricted blood flow, highlighting the need for the development of new surgical methods. The unsatisfactory outcomes of current OMA surgeries result from ischemic damage caused by both cauterization and suturing methods, regardless of whether they are performed using CL or RAL. However, the surgical flexibility of RAL offers significant potential for the development of innovative surgical techniques. Leveraging this flexibility, we developed a novel OMA surgical method, termed ROS-RAL, which has demonstrated a dramatic improvement in the preservation of ovarian reserve and function. In ROS-RAL OMA surgery, hemostasis in the vascular-rich ovarian stroma, where the OMA is removed, is achieved through meticulous interrupted suturing to reapproximate the incised ovary. Unlike previous cauterization or suturing methods, where hemostasis is harshly achieved through forcible techniques causing ischemic damage, hemostasis in ROS-RAL surgery is passively achieved by interrupted suturing of the incised ovarian stroma. The reapproximation of the incised ovarian stroma by interrupted suturing in ROS-RAL surgery provides sufficient hemostasis and allows the natural closure of the incised ovarian cortex. Overzealous hemostasis using energy devices can lead to thermal spread, resulting in ischemic damage to the inner ovarian stromal connective tissue that contains ovarian follicles. The ROS-RAL technique allows for targeted and precise suture ligation of bleeding sites, preventing unnecessary devascularization and destruction of normal ovarian tissue, optimizing the restoration of ovarian blood supply, and thereby better preserving ovarian reserve. Considering that targeted suturing on connective tissues such as stroma, widely adopted in general surgery, has been shown to be effective for hemostasis, it is not surprising that the reapproximation of the incised ovarian stroma achieves sufficient hemostasis in the ROS-RAL surgical method. The most unique aspect of ROS-RAL OMA surgery is its use of targeted interrupted sutures on the incised ovarian stroma to achieve hemostasis through reapproximation of the incised ovarian stroma. This method reapproximates the incised ovarian stroma, allowing the ovarian cortex to close naturally and the incised ovary to heal gradually. This approach minimizes trauma to ovarian tissue and optimizes postoperative restoration of ovarian blood supply, thereby more effectively preserving ovarian reserve. Our study demonstrated that ROS-RAL OMA surgery was significantly more effective in preserving ovarian reserve in patients with OMA compared to current OMA surgical methods. The ROS-RAL OMA group exhibited significantly higher AMH levels at all postoperative time points (1, 12, and 36 months) (Table  2 ) compared to the CL group, with a notably lower rate of AMH decline. Furthermore, the incidence of DOR at the 36-month follow-up was significantly lower in the RAL group than in the CL group (27.54% vs. 44.71%, P  = 0.028) (Table  3 ). In addition, the study explored factors influencing postoperative DOR and identified that age, bilateral endometriomas, the CL surgical platform, and preoperative AMH levels were associated with DOR incidence (Table  4 ). Notably, during the 36-month postoperative follow-up, five patients in the CL group experienced a recurrence of OMA, resulting in a recurrence rate of 5.88%. In contrast, no cases of recurrence were observed in the RAL group (Supplemental Fig. 3D). In summary, this study demonstrated the clinical advantages of RAL using the ROS surgical technique for the excision of OMA, offering superior postoperative ovarian function preservation compared to traditional RAL or CL. With a follow-up period of up to three years, this study provides long-term data illustrating the impact of ROS-RAL OMA surgery on ovarian reserve. However, despite the statistical significance of these findings, our study had some limitations. First, the relatively small sample size may limit its generalizability. Second, as a single-center study, the results may be influenced by the specific surgical team’s expertise, potentially limiting the broader applicability of the conclusions. Additionally, surgical skills and experience may impact outcomes, and future studies should consider this factor.

Ovarian endometriosis (endometrioma, OMA) is a disease in which endometrial-like tissues grow inside or on the surface of the ovaries, undergoing hemorrhagic changes with each menstrual cycle [ 1 ]. Endometrial-like tissue invades the ovaries, forming cysts knowns as OMA. OMA is the most common manifestation of endometriosis, accounting for 17% to 44% of cases [ 2 ]. As the condition progresses, the cysts enlarge, causing extensive adhesions with surrounding pelvic tissues and damaging the ovarian cortex, thereby impairing its function. Patients with OMA experience symptoms such as pelvic pain, dyspareunia, abnormal menstruation, infertility, and decreased ovarian function, severely affecting their quality of life and reproductive health [ 3 ]. Lifestyle factors and dietary patterns have also been shown to influence the development and progression of endometriosis [ 4 ]. OMA negatively impact fertility and can reduce ovarian reserve [ 5 ]. With the growing demand for fertility preservation, protection of ovarian function has become particularly critical [ 6 , 7 ]. Despite its seriousness, there is currently no medication specifically for OMA, and only management drugs, such as hormonal treatments, are used for the purpose of relieving the symptoms. Surgical excision is generally recommended to treat OMA, particularly for patients with cysts larger than 4 cm in diameter, significant pain, poor response to medication, or infertility issues with a desire for childbearing [ 8 ]. Application of laparoscopy in OMA treatment improves clinical outcomes compared to conventional laparotomy. Laparoscopic surgery offers several advantages, including less postoperative pain, shorter hospital stays, lower rates of adhesion formation, and a smaller impact on ovarian function [ 9 , 10 ]. Additionally, laparoscopic cystectomy effectively reduces the recurrence of endometriotic cysts [ 11 ], and when combined with progestins or short-term contraceptives, can significantly lower postoperative pain rates. Consequently, laparoscopic excision is widely used in clinical [ 12 ]. However, conventional laparoscopy (CL) has certain limitations. For example, the restricted range and flexibility of the instruments can make the surgery more challenging [ 13 ]. The two-dimensional surgical view makes it difficult to identify and completely excise hidden pathological lesions. Furthermore, prolonged surgeries can lead to surgeon fatigue, potentially affecting surgical precision. In particularly, CL has not shown satisfactory results for OMA, especially in advanced-stage endometriosis of stage 3 or higher [ 14 ]. Although advanced magnetic resonance imaging techniques have improved preoperative assessment of deep infiltrating lesions and complex pelvic anatomy, they do not fundamentally address the ovarian damage caused by the surgical procedure itself [ 15 ]. The advent of da Vinci robot-assisted laparoscopy (RAL) has demonstrated the potential to overcome the limitations of CL. In patients with stage III-IV OMA, classified according to the ASRM endometriosis scoring system, which often involves extensive and dense pelvic adhesions1 [ 16 ], RAL—featuring 360° rotating mechanical arms and multiple degrees of freedom—improves surgical ergonomics and enables more precise adhesion dissection in most surgical cases [ 17 ]. Compared to CL, RAL allows surgeons to perform complex and delicate procedures in confined spaces, facilitating the full dissection of “frozen pelvis” conditions in stage IV endometriosis patients without requiring colon resection [ 18 ]. Despite the advancements in surgical flexibility offered by RAL, the current surgical outcomes of OMA surgery performed with RAL does not demonstrate a clear benefit in preserving postoperative ovarian re serve [ 19 ]. This is because the surgical procedures employed in both methods are fundamentally the same. In typical CL and RAL OMA surgeries, bleeding sites encountered after a stripping cystectomy are cauterized before suturing. However, cauterization inevitably causes significant thermal damage to the ovary, as the process involves burning tissue to achieve hemostasis. Suture techniques have been proposed due to concerns about ischemic irreversible thermal damage caused by cauterization. In the case of a method of achieving hemostasis through pure suturing without cauterization, the ovary is penetrated, and the entire ovary is ligated multiple times during suturing. While this approach avoids the thermal damage caused by cauterization, the tight physical force exerted on the entire ovary results in ischemic damage by reducing blood flow to the ovarian cortex and stroma. Consequently, the surgical outcomes of the suturing method are not significantly better than those of the cauterization method [ 20 ]. Since current surgical techniques for OMA are basically similar regardless of whether CL or RAL is used, the outcomes of RAL OMA surgery are not markedly different from those of CL [ 19 ]. Considering the surgical flexibility of RAL compared to CL, RAL has the potential to facilitate the development of new surgical methods that could overcome the limitations of current OMA surgeries. By leveraging its advanced capabilities, RAL may pave the way for improved approaches to enhance surgical outcomes and better preserve ovarian function in patients with OMA. Preservation of ovarian function is one of the primary clinical concerns in patients with OMA. With the widespread use of assisted reproductive technologies, accumulating evidence suggests that assisted reproductive technologies may be associated with an increased risk of certain birth defects, such as congenital heart disease, and may impose a substantial psychological burden on patients [ 21 – 24 ]. Therefore, promoting natural conception while reducing reliance on assisted reproductive technologies has become an important goal in the clinical management of OMA. Accordingly, numerous studies have explored the beneficial effects of optimizing ovarian physiology and improving metabolic homeostasis on reproductive outcomes [ 25 – 27 ]. Given the critical importance of ovarian reserve for fertility and pregnancy, there is an urgent need to develop a new surgical method that effectively removes OMA while preserving ovarian reserve. In this work, we developed a novel RAL surgical method called Reapproximation of Ovarian Stroma (ROS), leveraging the surgical flexibility offered by RAL. This ROS-RAL OMA surgical method is to suture only the vascular-rich ovarian stroma while avoiding the cortex after cystectomy, with the aim of avoiding thermal damage caused by cauterization and reducing physical damage to the ovarian cortex caused by tightly sewn sutures. At this time, the ovarian incision site is either tied with a suture just around the edges of the incision to maintain the shape of the ovary, or left unsutured. This approach proved effective in treating advanced-stage endometriosis and demonstrated a significant advantage in preserving ovarian function postoperatively, even in patients with OMA of advanced-stage endometriosis.

Below is the link to the electronic supplementary material. Supplementary Material 1 Supplementary Material 1