The impact of the number of stapler firings on anastomotic leakage in minimally invasive rectal surgery: risk factor or technical marker of complexity? A systematic review, meta‑analysis, and metaregression

Background Anastomotic leakage is a major complication after minimally invasive anterior resection for rectal cancer. The number of stapler firings for rectal transection has been suggested as a modifiable risk factor, but its independent role and optimal threshold remain unclear. Objective To evaluate the impact of the number of stapler firings on anastomotic leakage after rectal surgery and to assess the influence of surgical and patient-related variables. Data Sources A comprehensive search of PubMed, Cochrane Library, and Ovid MEDLINE was performed. Study Selection Studies reporting anastomotic leakage rates stratified by stapler firing count (one, two, or three or more) were included. Intervention(s) Rectal transection with one or more stapler firings during minimally invasive anterior resection for rectal cancer. Main Outcome Measures Incidence of anastomotic leakage according to stapler firing (SF) count. Results Twenty two studies including 8,725 patients and 784 anastomotic leakage events were analyzed. A single stapler firing was associated with a significantly reduced risk of anastomotic leakage compared with two stapler firings (odds ratio 0.57, 95% confidence interval 0.39–0.83), three or more stapler firings (odds ratio 0.28, 95% confidence interval 0.16–0.51), and two or more stapler firings (odds ratio 0.46, 95% confidence interval 0.34–0.63). The risk of anastomotic leakage was lower with fewer than three stapler firings compared with three or more stapler firings (odds ratio 0.38, 95% confidence interval 0.30–0.48). Meta-regression identified low rectal transection and preoperative radiotherapy as significant effect modifiers. Limitations All included studies were observational, introducing potential bias and increased heterogeneity and the certainty of evidence was low across all comparisons. Conclusions Three or more stapler firings were consistently associated with a higher risk of anastomotic leakage. However, because the certainty of evidence was low and owing to exploratory meta-regression findings, stapler firing number appears to reflect operative complexity more than a definitively established independent causal risk factor.