Gasless vaginal natural orifice transluminal endoscopic surgery(vNOTES): a safe and feasible approach for adnexal procedures

The primary limitation of this study is its retrospective, non-comparative design. As a retrospective case series without a control arm, this study cannot definitively prove that gasless vNOTES is superior to conventional pneumoperitoneum vNOTES in terms of pain, recovery, or operative time. Our findings should therefore be considered preliminary, and prospective randomized controlled trials are needed to confirm them. Furthermore, the study population consisted predominantly of patients with ovarian teratomas who underwent ovarian cystectomy, which may restrict the generalizability of our findings. Consequently, whether gasless vNOTES is suitable for conditions associated with a higher risk of adhesions, such as ovarian endometriomas, still needs to be studied in larger and more diverse patient cohorts.

The study included patients treated between September 2024 and August 2025 at the International Peace Maternity and Child Health Hospital in Shanghai. Participants were selected through review of electronic medical records and had undergone vNOTES without pneumoperitoneum for benign adnexal conditions. Exclusion criteria comprised: obliterated pouch of Douglas on pelvic examination, suspected severe pelvic adhesions, suspected deep endometriosis (e.g., rectovaginal endometriosis), suspected gynecologic malignancy, acute vaginitis, acute pelvic inflammatory disease, and cases scheduled for vNOTES in which abdominal cavity access was not feasible for various reasons. Patient baseline demographics and perioperative characteristics were retrieved from our institutional medical database. The collected variables included age, body mass index (BMI), obstetric history, history of abdominal or pelvic surgery, pathological type of adnexal mass, surgical procedure, operative time, intraoperative blood loss, conversion rate to conventional gas-based vNOTES or laparoscopy, complications, pain assesed using a Visual Analog Scale (VAS, scored from 0 to 10) at 2 h, 6 h, and 12 h after surgery, time to first flatus, postoperative infection rate and postoperative hospital stay. Postoperative outcomes at 3 months were retrospectively collected from scheduled outpatient follow-up records, or from telephone interviews when in-person follow-up was unavailable. Prophylactic antibiotics (cefoxitin 2 g, or clindamycin 0.6 g for patients with cephalosporin allergy) were administered 30 min before surgery. Patients were placed in the lithotomy position and then in the Trendelenburg position. Following the induction of general anesthesia, transvaginal ultrasound was performed using the sliding sign technique to assess adhesions in the pouch of Douglas. The perineum and vagina were disinfected with 10% povidone iodine solution. A Foley catheter was inserted to drain the bladder and was removed immediately after surgery. The surgical team consisted of one expert surgeon (Dr. Lu) with more than two years of vNOTES experience and one assistant. A posterior colpotomy approximately 2.5 cm in length was first performed using cold scissors. Through this incision, the inner ring of the 7-cm wound retractor (Beijing Aerospace Kadi Technology Development Institute) was introduced. The surgeon manually checked that the ring was completely deployed. The outer ring was rolled inward twice. Under direct visualization with a 10-mm 30° laparoscope, one or two sterile gauze pads (9 cm × 10 cm) were inserted into the pelvic cavity to displace the bowel superior to the uterus, thereby creating a safe operative space. For ovarian masses located anterior to the uterus, the uterus was first elevated with a flat forceps to expose the abdominal cavity. In most cases, the mass could be displaced into the posterior pelvis either by gravity or by gentle instrumental manipulation. In rare cases where the mass remained obscured or proved difficult to mobilize, brief insufflation was performed. Once adequate intra-abdominal space was achieved, the mass gained increased mobility, facilitating its exposure and subsequent retraction into the posterior pelvis. Immediately thereafter, desufflation was carried out, and the standard gasless vNOTES procedure was resumed. Following adequate exposure of the adnexa, standard adnexal surgery was performed (Fig.  1 A). The assistant held the laparoscope with one hand while using an aspirator in the other to continuously clear smoke and blood from the surgical field, ensuring optimal visibility. If the excised specimen was large, it was placed into a retrieval bag before removal. In cases of ruptured ectopic pregnancy with significant hemoperitoneum, a reverse Trendelenburg (head-up) position was employed to facilitate gravitational drainage of blood from the upper abdomen toward the pelvic cavity, where it could be aspirated under direct endoscopic visualization. Upon completion of the procedure, the pelvic cavity was thoroughly cleaned, and the gauze was removed. After extraction of the single-port device, the colpotomy incision was closed with a continuous suture. Postoperative prophylactic antibiotics were readministered 12 h later to reduce the risk of infection. Fig. 1 ( A) Operative view of gasless vNOTES using the wound retractor and laparoscopic instruments; ( B - C ): Comparison of surgical field between gasless ( B ) and pneumoperitoneum vNOTES ( C ) in ovarian cystectomy; black arrow indicate gauze. vNOTES = vaginal natural orifice transluminal endoscopic surgery ( A) Operative view of gasless vNOTES using the wound retractor and laparoscopic instruments; ( B - C ): Comparison of surgical field between gasless ( B ) and pneumoperitoneum vNOTES ( C ) in ovarian cystectomy; black arrow indicate gauze. vNOTES = vaginal natural orifice transluminal endoscopic surgery All analyses were performed using SPSS version 21.0 (IBM, Armonk, NY, USA). Categorical variables were presented as numbers and percentages (%). Continuous variables following a normal distribution were expressed as mean ± standard deviation (SD), whereas non‑normally distributed variables were summarized as median with interquartile range (IQR). Given the low proportion of missing data and the assumption of missingness at random, a complete-case analysis was adopted, and no missing data were imputed. As no statistical comparisons were planned in this study, a formal significance threshold was not defined.

From September 2024 to August 2025, 373 patients underwent adnexal surgery via vNOTES. Only 3 cases (0.8%) required surgical conversion from gasless vNOTES. Among these, one patient was converted to gas‑based vNOTES and two to TU-LESS due to pelvic adhesions. The remaining 370 patients successfully completed gasless vNOTES procedures. Figure  1 B shows an example of surgical exposure. The mean age of these 370 patients was 31.03 ± 6.82 years, and the mean BMI was 21.61 ± 3.18 kg/m². Of these, 63.2% (234/370) were nulliparous, and 18.9% (70/370) had a history of abdominal or pelvic surgery. Patient characteristics are presented in Table  1 . Table 1 Patient characteristics Characteristics Total ( n  = 370) Age (years, mean ± SD) 31.03 ± 6.82 BMI (kg/m 2 , mean ± SD) 21.61 ± 3.18 Gravidity (n, %) 0 199 (53.8%) 1 98 (26.5%) ≥ 2 73 (19.7%) Parity (n, %) Nulliparous 234 (63.2%) Vaginal delivery 1 71 (19.2%) ≥ 2 23 (6.2%) Caesarean section 1 36 (9.7%) ≥ 2 6 (1.6%) Previous abdominal or pelvic surgery (n, %) 70 (18.9%) SD  standard deviation, BMI  body mass index Patient characteristics SD  standard deviation, BMI  body mass index As shown in Table  2 , the surgical and pathological distributions were as follows: ovarian cystectomy ( n  = 314, 84.9%), salpingectomy for ectopic pregnancy ( n  = 29, 7.8%), salpingotomy for embryo extraction ( n  = 10, 2.7%), adnexectomy ( n  = 10, 2.7%). Concurrent procedures included paratubal cystectomy ( n  = 66, 17.8%), hysteroscopies ( n  = 35, 9.5%), and adhesiolysis ( n  = 24, 6.5%). Pathologically, ovarian cysts ( n  = 323, 87.3%)—predominantly mature cystic teratoma ( n  = 292, 78.9%)—were most common, followed by tubal pregnancy ( n  = 38, 10.3%). The mean maximum lesion diameter of ovarian cysts was 6.06 ± 1.92 cm (range: 2.4–12.3 cm), with 18.0% (58/323) lesions ≥ 8 cm. Table 2 Surgical procedures and Pathologic outcomes Characteristics N  = 370 Surgical procedure Type of procedure (n, %) Ovarian cystectomy 314 (84.9%) Salpingectomy 29 (7.8%) Salpingo-oophorectomy 10 (2.7%) Salpingotomy for embryo extraction 10 (2.7%) Paratubal cystectomy 6 (1.6%) Excision of ovarian pregnancy 1 (0.3%) Additional procedure during surgery (n, %) Paratubal cystectomy 66 (17.8%) Hysteroscopies (with or without resection) 35 (9.5%) Lysis of adhesions 24 (6.5%) Myomectomy 12 (3.2%) Hydrotubation 3 (0.8%) Tubal ligation 2 (0.5%) Loop electrosurgical excision procedure 4 (1.1%) Trans-obturator tension-free vaginal tape  1 (0.3%) Pathological type of main diagnosis (n, %) Mature cystic teratoma 292 (78.9%) Mucinous cystadenoma 9 (2.4%) Serous cystadenoma 8 (2.2%) Endometriotic cyst 7 (1.9%) Simple cyst 4 (1.1%) Fibroma 2 (0.5%) Serous Borderline malignancy 1 (0.3%) Paratubal cyst 7 (1.9%) Tubal pregnancy 38 (10.3%) Ovarian pregnancy 1 (0.3%) Hydrosalpinx 1 (0.3%) Maximum diameter of ovarian cysts (cm, mean ± SD) 6.06 ± 1.92 Diameter of cyst ≥ 8 cm (n, %) 58 (18.0%) Diameter of cyst < 8 cm (n, %) 265 (82%) SD  standard deviation, cm  centimeter Surgical procedures and Pathologic outcomes SD  standard deviation, cm  centimeter The perioperative and postoperative outcomes of the 370 patients are summarized in Table  3 . The mean operative time was 54.41 ± 25.94 min (range: 13–190 min). When stratified by pathology, the mean operative time for ovarian cysts ≥ 8 cm was 83.84 ± 35.96 min, compared with 51.01 ± 19.04 min for cysts < 8 cm. The shortest mean operative time was observed in ectopic pregnancy cases (37.33 ± 15.21 min, range: 13–85 min). Intraoperative blood loss averaged 25.63 ± 14.31 mL. No intraoperative complications such as visceral injury or major hemorrhage occurred. In 5 cases (1.4%), the ovarian cyst was located anterior to the uterus, making exposure difficult. Brief intraoperative insufflation (< 5 min) was applied to retract the mass posterior to the uterus, and then gasless vNOTES was continued after desufflation. Table 3 Perioperative and postoperative outcomes Characteristics Total ( n  = 370) Total operation time (min, mean ± SD) 54.41 ± 25.94 for ovarian cysts ≥ 8 cm 83.84 ± 35.96 for ovarian cysts < 8 cm 51.01 ± 19.04 for ectopic pregnancy 37.33 ± 15.21 Estimated blood loss (mL, mean ± SD) 25.63 ± 14.31 Transient pneumoperitoneum (n, %) 5 (1.4%) Intraoperative complication (n, %) 0 (0%) Postoperative VAS pain score [ Median (P25, P75)] At 2 h 2.0 (1.0, 3.0) At 6 h 1.0 (0.0, 2.0) At 12 h 0.0 (0.0, 1.0) Postoperative fever Temperature ≥ 38 °C (n, %) 17 (4.6%) Postoperative infection (n, %) 7 (1.9%) Postoperative analgesia (n, %) 4 (1.1%) Postoperative urinary retention (n, %) 3 (0.8%) Time of first flatus (h, mean ± SD) 7.12 ± 4.51 Time of first postoperative ambulation (h, mean ± SD) 2.78 ± 1.34 Postoperative hospital stay (h, mean ± SD) 22.09 ± 10.36 SD  standard deviation, VAS  visual analog scale, mL  milliliter, cm  centimeter Perioperative and postoperative outcomes Time of first postoperative ambulation (h, mean ± SD) SD  standard deviation, VAS  visual analog scale, mL  milliliter, cm  centimeter The median postoperative VAS pain scores at 2, 6, and 12 h after surgery were 2.0 (1.0, 3.0), 1.0 (0, 2.0), and 0 (0, 1.0), respectively. Postoperative analgesia was administered on demand. Only 4 patients (1.1%) required rescue analgesia, all of whom received a single oral dose of ibuprofen sustained-release capsules (300 mg). No patient required opioids or intravenous analgesics. No routine prophylactic analgesics were given. Seventeen patients (4.6%) developed fever (temperature ≥ 38 °C), of whom seven (1.9%) were diagnosed with postoperative infection. These included three cases of mycoplasma pneumonia and one case of acute gastroenteritis. All postoperative infection cases recovered after antibiotic treatment. Other complications included urinary retention in three patients (0.8%), all of which resolved after a single catheterization. Recovery parameters were favorable: the mean time to first flatus was 7.12 ± 4.51 h, and the mean time to first ambulation was 2.78 ± 1.34 h. Most patients were discharged on the first postoperative day, with a mean postoperative hospital stay of 22.09 ± 10.36 h. During the 3‑month follow‑up via outpatient visit or telephone interview, no cases of wound infection or hematoma were observed.

Transvaginal natural orifice transluminal endoscopic surgery (vNOTES) for gynecology is a novel minimally invasive procedure first reported in 2012 [ 1 ]. It has gained widespread adoption due to its notable advantages over conventional laparoscopy, including less postoperative pain, quicker recovery, no abdominal scarring, and better cosmetic outcomes [ 2 , 3 ]. The procedure is now increasingly employed for a variety of gynecological operations such as ovarian cystectomy, salpingectomy, myomectomy, hysterectomy, and pelvic organ prolapse repair [ 4 – 10 ], with its safety and efficacy well documented in the literature [ 4 , 11 – 14 ]. Nevertheless, vNOTES has technical limitations compared with traditional laparoscopy, such as restricted instrument triangulation and increased intraoperative interference [ 15 , 16 ]. Moreover, conventional vNOTES depends on CO₂ pneumoperitoneum to maintain the operative space, which raises the risk of related complications like postoperative pain and hypercapnia [ 17 , 18 ]. Gasless vNOTES has been proposed to mitigate external instrument conflict and reduce pneumoperitoneum‑associated risks [ 18 – 20 ]. However, existing gasless techniques often require additional parietal invasive material to lift the abdominal wall, potentially adding to procedural complexity and causing additional abdominal trauma [ 18 , 20 ]. During conventional vNOTES adnexal surgery, we incidentally observed that the procedure could be performed smoothly without gas insufflation or abdominal wall retractors. This approach improved visual field clarity, operative convenience, and shorter operative time. To further evaluate this approach, we conducted a retrospective study of 373 patients who underwent gasless vNOTES for adnexal surgery at our institution. This study aimed to evaluate the feasibility and safety of gasless vNOTES in this clinical context.

In conclusion, gasless vNOTES is a safe and reliable technique for benign adnexal surgery, with a low conversion rate. It offers convenient operation, short operative time, low postoperative pain, fast recovery, and cost-effectiveness, positioning it as a promising approach to replace traditional gas‑based vNOTES and merits broader clinical adoption. However, given the retrospective and descriptive nature of this study, further randomized controlled trials are needed to determine its full clinical application.

This study demonstrates that gasless vNOTES is a safe and feasible approach for adnexal surgery. In September 2024, during a conventional vNOTES procedure, Dr. Lu observed that ovarian cystectomy could be successfully performed without pneumoperitoneum. Based on this finding, an observational study was conducted to evaluate gasless vNOTES for adnexal surgery. During the course of this research, with conclusions similar to ours, an early experience on gasless vNOTES without an abdominal wall traction device was reported [ 21 ]; however, that study had a small sample size and primarily involved salpingectomy for ectopic pregnancy. Our findings indicate no significant difference in the surgical field between gasless and pneumoperitoneum vNOTES ( Fig.  1 B and C). Under gasless conditions, the uterus is positioned superiorly in the surgical field, while the intestines are gently packed anteriorly with gauze, creating a semi-enclosed operating space. Owing to this semi-closed environment, even if the cyst ruptures, the cyst fluid does not drain easily into the upper abdomen. The packed gauze can both block and absorb the fluid. Moreover, under gasless vNOTES, the assistant can promptly suction away any cyst fluid using an aspirator. In our previous cases of cystectomy performed via pneumoperitoneum-assisted vNOTES, exploration of the upper abdomen revealed no evidence of cyst fluid contamination. In contrast, although pneumoperitoneum increases the volume of the abdominal cavity, the pelvic operative view does not expand significantly because of posterior uterine compression. Therefore, insufflation may be unnecessary. In this study, the mean operative time was 54.41 ± 25.94 min. Specifically, ovarian cystectomies for masses < 8 cm averaged 51.01 ± 19.04 min, while ectopic pregnancy surgeries averaged 37.33 ± 15.21 min, with the shortest time being 13 min. These results are similar to those reported by Gauci et al. [ 21 ] (mean operative time 27.4 ± 10.8 min) in a study predominantly involving fallopian tube procedures. Previous literature indicates that conventional vNOTES adnexal surgery requires 70–85 min [ 12 , 22 , 23 ], even for masses mostly smaller than 8 cm. Moreover, even with 426 cases of ectopic pregnancy treated by traditional vNOTES, the average operative time exceeded 68 min [ 5 ]. These results suggest that gasless vNOTES may have the potential to reduce operative time. Possible reasons include the following. First, the absence of a multi-channel port outside the wound protector in gasless vNOTES creates an opening similar to that of a small incision, which increases the effective diameter of the operating port and alleviates the so-called “chopsticks effect”—a phenomenon commonly encountered in single-port laparoscopy, where instruments introduced through a single narrow access point tend to crowd together, collide externally, and lose the natural triangulation achieved in multi-port surgery. This restriction impairs instrument mobility, forces awkward hand positions, and increases surgeon fatigue. With a wider and more compliant access provided by the wound retractor alone, instruments can be spaced more freely, improving ergonomics and allowing smoother, more intuitive movements. Second, instruments can be inserted and withdrawn more conveniently through the open access. Third, the open configuration permits the simultaneous use of more instruments, enabling active assistant participation. Fourth, continuous suction can be applied to maintain a clear visual field without disrupting the working space. Although literature suggests that masses > 8 cm may not be suitable for vNOTES [ 24 , 25 ], this study included 58 cases (18.0%) of ovarian cysts ≥ 8 cm, with the largest measuring 12.3 cm. The mean operative time for these larger cysts was 83.84 ± 35.96 min, longer than for smaller masses, yet all procedures were completed successfully, likely due to improved maneuverability offered by the gasless approach. For large cysts (≥ 10 cm), the surgical strategy entails initial aspiration of the cyst fluid for decompression. Subsequently, the ovary is exteriorized through the colpotomy to facilitate extracorporeal cystectomy using conventional instruments, accompanied by simultaneous suturing under direct visualization. Finally, the ovary is returned to the pelvic cavity, followed by thorough endoscopic irrigation to aspirate any remaining fluid and blood. Postoperative pain scores in this series were very low. At 6 and 12 h post‑surgery, the vast majority of VAS scores ranged between 0 and 1, with almost no need for analgesic medication and no reported shoulder or rib pain associated with CO₂ pneumoperitoneum. In contrast, previous studies reported higher VAS scores at 12 h after pneumoperitoneum vNOTES (2.6 ± 1.9) [ 26 ], and Feng et al. [ 12 ] reported a median pain score of 3.0 (1.0, 5.0). This suggests that the gasless technique may have the potential to reduce postoperative pain and analgesic use, which has also been confirmed in gasless laparoscopic surgery, where lower pain levels—especially shoulder and rib pain—have been documented [ 27 , 28 ]. It should be noted, however, that one study on conventional vNOTES for ectopic pregnancy did report a relatively low VAS score of 0 (0, 2.5) at 12 h postoperatively, although this might be attributable to its small sample size [ 29 ]. Additionally, patients in our study were able to ambulate at an average of 2.78 ± 1.34 h post-surgery and experienced a short time to first flatus, averaging 7.12 ± 4.51 h. They were generally discharged on the first postoperative day. These findings suggest that gasless vNOTES facilitates rapid intestinal recovery and shortens hospital stay, making it suitable for day-surgery settings. Regarding postoperative infection risk, although vNOTES is considered a class II incision, with strict disinfection and perioperative antibiotic prophylaxis, the postoperative infection rate was only 1.9%. No surgical site or vaginal wound infections were observed. This low infection rate is comparable to the reported 2.0% infection rate after pneumoperitoneum vNOTES [ 12 ]. No complications such as intestinal or bladder injury occurred in this series; intraoperative blood loss was minimal, and follow‑up showed good wound healing without hematoma or abscess formation. Notably, if intraoperative insufflation is necessary for abdominal exploration or exposure, temporary pneumoperitoneum can still be employed before proceeding with the gasless technique. In this study, 24 cases (6.5%) presented with adhesions, yet all were completed successfully under gasless conditions, indicating that mild to moderate pelvic adhesions can be managed without pneumoperitoneum. However, severe or atypically located adhesions may require conversion to alternative approaches. Three cases in this study were converted: one for severe pelvic adhesions in ectopic pregnancy where the fallopian tube was difficult to expose—converted to pneumoperitoneum vNOTES; another for a tubal pregnancy adherent to the anterior leaf of the broad ligament, which could not be exposed even after insufflation and was converted to TU‑LESS; and a third for a right ovarian teratoma adherent between the anterior uterine wall and abdominal wall in a patient with a history of appendectomy, also converted to TU‑LESS. Furthermore, the single‑port access device for gasless vNOTES costs approximately $114, compared to about $600 for a pneumoperitoneum vNOTES port, highlighting the economic advantage of the gasless approach.