Paeoniflorin adjunct to scar release surgery for postoperative anorectal stenosis: a randomized controlled trial

Postoperative anorectal stenosis is a disabling complication of anorectal surgery, characterized by fibrotic narrowing that impairs defecation and quality of life. While scar-release surgery can restore lumen patency, long-term outcomes are undermined by recurrent fibrosis. Paeoniflorin, the active component of Shaobei Injection, is a promising botanical antifibrotic agent that may enhance perioperative efficacy. This study aims to evaluate whether combining Paeoniflorin with longitudinal scar-release surgery improves anatomical and functional outcomes in patients with postoperative anorectal stenosis compared to surgery alone.

In this prospective, multicenter randomized controlled trial (Trial registration: ChiCTR2200062631) in China. Eligible patients with iatrogenic fibrotic anorectal stenosis were randomized equally (1:1) to receive either scar-release surgery plus Paeoniflorin (experimental group) or surgery alone (control group). The primary endpoints were stricture relief rate (defined as anal canal diameter ≥20 mm) and improvement in defecation difficulty score at 1 and 6 months. Secondary outcomes included anal pain (VAS), scar tissue thickness (imaging), and stricture recurrence rate. All patients were followed for 6 months.

A total of 128 patients were enrolled and randomized (64 per group); after excluding 22 patients lost to follow-up, 106 patients (53 per group) completed the 6-month follow-up and were included in the final analysis. At 6 months, the stricture relief rate was significantly higher in the experimental group compared to the control group (90.6% vs. 73.6%; P < 0.05; RR, 1.23; 95%CI, 1.03-1.48). Mean defecation difficulty scores improved significantly in both groups, but the experimental group maintained near-normal scores (0.70 ± 0.27 at 1 month and 0.78 ± 0.17 at 6 months) compared to the control group (2.23 ± 0.88 and 2.34 ± 0.51, respectively; P < 0.05 for both time points). Secondary outcomes including reduced scar thickness and lower recurrence rates (3.8% vs. 13.2%, P = 0.08; RR, 0.29; 95%CI, 0.06-1.31) further favored the combined therapy. No injection-related adverse effects were observed.

These preliminary 6-month findings suggest that local paeoniflorin may provide exploratory benefits as an adjunct to scar-release surgery. Larger, longer-term trials are required to validate its clinical efficacy and durability.

https://www.chictr.org.cn/, ChiCTR2200062631.