Transanal tube for the prevention of anastomotic leakage in rectal cancer surgery.

Anastomotic leakage is a serious complication of rectal cancer surgery, causing morbidity and increasing healthcare burden. A diverting stoma reduces anastomotic pressure but carries risks. A transanal tube near the anastomosis may reduce spasms and drain stool, potentially lowering leakage risk. To evaluate the benefits and harms of a transanal tube for the prevention of anastomotic leakage in people undergoing rectal surgery, compared with no transanal tube. We searched Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via Ovid, Embase via ProQuest, and four clinical trial registries. The latest search was conducted on 6 August 2025. We included all randomised controlled trials (RCTs) that compared the use of a transanal tube with no intervention in adults undergoing rectal cancer surgery. The critical outcomes were anastomotic leakage, surgical re-intervention due to anastomotic leakage, and any postoperative adverse events other than anastomotic leakage within 30 days postoperatively. Important outcomes included the overall incidence of anastomotic leakage, postoperative length of hospital stay, accidental early removal of the transanal tube, and tube-related complaints. We used the Cochrane RoB 2 tool to assess risk of bias in the included RCTs. We used random-effects meta-analyses to calculate risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI). If meta-analysis was not feasible, we summarised the findings narratively. Heterogeneity was assessed using the I² statistic, and substantial heterogeneity (I² > 50%) was explored via prespecified subgroup analysis. The certainty of evidence was evaluated with GRADE. Due to substantial heterogeneity in anastomotic leakage data, possibly influenced by diverting stoma status, we performed prespecified subgroup analyses according to diverting stoma status. Four RCTs were included, involving 1318 participants: 666 in the transanal tube group and 652 in the no-intervention group. All included studies were judged to have an overall risk of bias of "some concerns". Overall, the certainty of evidence ranged from very low to low because of the risk of bias, inconsistency, and imprecision. The evidence is very uncertain about the effect of a transanal tube on the risk of anastomotic leakage (RR 0.88, 95% CI 0.46 to 1.72; 4 RCTs, 1318 participants; very low-certainty evidence). The anticipated absolute risk of anastomotic leakage was 83 per 1000 in the no-intervention group and 73 per 1000 (95% CI 38 to 142) in the transanal tube group (NNT = 100). A test for subgroup differences suggested that the effect of a transanal tube differed according to diverting stoma status (P = 0.03). Among people without a diverting stoma, the RR for anastomotic leakage was 0.72 (95% CI 0.36 to 1.43; 3 RCTs, 911 participants). The anticipated absolute risk was 89 per 1000 in the no-intervention group and 64 per 1000 (95% CI 32 to 127) in the transanal tube group. Among people with a diverting stoma, the RR was 2.38 (95% CI 1.00 to 5.69; 2 RCTs, 250 participants). The anticipated absolute risk was 52 per 1000 in the no-intervention group and 124 per 1000 (95% CI 52 to 297) in the transanal tube group. A transanal tube may reduce the risk of surgical re-intervention for anastomotic leakage (RR 0.32, 95% CI 0.10 to 1.00; 3 RCTs, 1124 participants; low-certainty evidence). The anticipated absolute risk of surgical re-intervention for anastomotic leakage was 45 per 1000 in the no-intervention group and 14 per 1000 (95% CI 4 to 45) in the transanal tube group (NNT = 33). Among people without a diverting stoma, the RR for surgical re-intervention for anastomotic leakage was 0.25 (95% CI 0.07 to 0.94; 2 RCTs, 806 participants). The evidence is very uncertain about the effect of a transanal tube on the risk of postoperative adverse events other than anastomotic leakage (RR 1.19, 95% CI 0.76 to 1.88; 2 RCTs, 555 participants; very low-certainty evidence). The anticipated absolute risk was 174 per 1000 in the no-intervention group and 207 per 1000 (95% CI 132 to 327) in the transanal tube group (NNH = 30). Among people without a diverting stoma, the RR for postoperative adverse events other than anastomotic leakage was 1.39 (95% CI 0.94 to 2.04; 1 RCT, 398 participants). The evidence is very uncertain about the effect of a transanal tube on the risk of overall anastomotic leakage (RR 0.87, 95% CI 0.46 to 1.66; 4 RCTs, 1318 participants; very low-certainty evidence). The anticipated absolute risk of overall anastomotic leakage was 87 per 1000 in the no-intervention group and 76 per 1000 (95% CI 40 to 145) in the transanal tube group (NNT = 91). One RCT involving 398 participants, all without a diverting stoma, found that a transanal tube may reduce postoperative length of hospital stay (MD -3.25 days, 95% CI -4.55 to -1.95; low-certainty evidence). Accidental early transanal tube removal occurred in 2.7% (range 0-8.2%) of participants with a transanal tube. Tube-related complaints were reported in 25.2% of participants (range 1.9-46.4%). A transanal tube may reduce the risk of surgical re-intervention for anastomotic leakage. However, its effect on anastomotic leakage remains uncertain. Subgroup analyses suggested that the effect may differ according to diverting stoma status, with more anastomotic leakage observed with a transanal tube among people with a diverting stoma. Future trials should report outcomes separately according to diverting stoma status and standardise transanal tube characteristics. This Cochrane Review did not receive direct funding from any organisation. The protocol is available at doi.org/10.1002/14651858.CD015472.