To evaluate the clinical utility of a modified anvil placement technique in laparoscopic resection of low rectal cancer with transanal eversion and specimen extraction without an auxiliary abdominal incision (NOSES type Ⅰ, technique B).

Consecutive patients with low rectal cancer who underwent NOSES type I, procedure B, using either of two anvil placement techniques at the Department of Colorectal and Anal Surgery, the First Affiliated Hospital of Zhengzhou University, between January 2021 and September 2023 were retrospectively identified. Of the 60 patients screened, 4 were excluded because of incomplete data, leaving 56 patients for analysis. Patients were categorized according to the anvil placement technique used into an observation group (modified extracorporeal anvil placement, n=29) and a control group (conventional intracorporeal anvil placement, n=27). In the modified group, the technique previously developed by our team was performed as follows: after total mesorectal excision and adequate mobilization of the proximal sigmoid colon, the rectal stump was everted through the anus, and distal transection was performed under direct vision. The proximal sigmoid colon was then exteriorized transanally, allowing anvil insertion and fixation with a purse-string suture under direct vision. The colon was subsequently returned to the abdominal cavity, and a circular stapled anastomosis was completed. In the conventional group, the anvil was inserted intracorporeally through an incision in the proximal sigmoid stump. Anvil placement time, perioperative outcomes, 30-day complications, pathological outcomes, and oncological follow-up outcomes were compared between groups.

The overall postoperative complication rate was significantly lower in the modified group than in the conventional group [3.4% (1/29) vs. 22.2% (6/27); P=0.048]. Anvil placement time was also significantly shorter in the modified group [4.7 (2.0, 6.0) vs. 8.0 (5.0, 10.0) min; Z=4.89, P＜0.01]. Operative time (157.0 vs. 173.0 min) and intraoperative blood loss (50.0 vs. 50.0 mL) did not differ significantly between groups. No significant differences were observed in time to first flatus, first bowel movement, resumption of oral intake, or ambulation. Lymph node yield, resection margins, and specimen integrity were comparable between groups. At a median follow-up of 42.2 months, the 3-year overall survival rates were 93.1% and 88.9%, and the 3-year disease-free survival rates were 96.6% and 92.6% in the modified and conventional groups, respectively; neither difference was statistically significant.

In selected patients with low rectal cancer undergoing NOSES type Ⅰ technique B, modified extracorporeal anvil placement showed technical convenience and was associated with a shorter anvil placement/fixation time and a lower 30-day postoperative complication rate in this study. Its safety and potential benefits require confirmation in prospective, multicenter studies with larger samples.