Anorectal function after transanal natural orifice specimen extraction for colorectal cancer: a systematic review and meta-analysis

Purpose Natural orifice specimen extraction (NOSE) eliminates the abdominal extraction incision after minimally invasive (MIS) colorectal resection and offers favourable short-term recovery, but transanal extraction raises concerns regarding sphincter stretch and anorectal dysfunction. This review evaluated anorectal functional outcomes after transanal NOSE compared with transabdominal specimen extraction (TASE) in MIS colorectal cancer surgery. Methods MEDLINE and EMBASE were searched from inception to August 2024 for comparative studies reporting postoperative anorectal or pelvic floor functional outcomes following transanal NOSE versus TASE. The primary outcome was anorectal continence at the postoperative interval closest to 6 months. Results Ten retrospective cohort studies were included, of which seven (1362 patients) contributed quantitative data for meta-analysis. Three studies contributed to the pooled Wexner incontinence score analysis and four to the pooled Pelvic Floor Distress Inventory short form (PFDI-20) analysis. At the interval closest to 6 months, Wexner scores were numerically higher after transanal NOSE than TASE, but the difference was small and non-significant (MD 0.17, 95% CI − 0.01 to 0.35; p = 0.07). PFDI-20 scores did not differ between groups (MD − 0.02, 95% CI − 0.21 to 0.18; p = 0.86). Both estimates were robust in leave-one-out and overlap-adjusted analyses excluding potentially overlapping Harbin Medical University cohorts. Early differences appeared to diminish over time, with no clear separation beyond 12 months. Conclusion Transanal NOSE was associated with a small, non-significant trend toward higher early Wexner scores after MIS colorectal cancer surgery, while broader pelvic floor symptom burden appeared comparable to TASE. The difference was of uncertain clinical significance, was robust to sensitivity analyses, and longer-term data suggested no persistent functional disadvantage.