Cumulative Surgeon Experience and Anastomotic Leakage After Left-Sided and Segmental Colorectal Resection with Primary Anastomosis: A Seven-Year Single-Center Retrospective Study

Background and Objectives: Anastomotic leakage (AL) remains one of the most feared complications following colorectal resection, yet the relationship between cumulative surgeon experience and AL risk remains inconclusive in the literature. Most available evidence originates from high-volume or specialized centers, with limited data from mid-volume Central and Eastern European settings. This study aimed to evaluate the association between cumulative surgeon experience, operative time, and AL risk in a selected sample of colorectal resections with primary anastomosis for both benign and malignant indications, excluding right colectomies, abdominoperineal resections, TaTME, Hartmann’s procedures, and stoma-protected anastomoses, within a single-center multi-surgeon setting over a seven-year period. Materials and Methods: This retrospective observational study included 315 consecutive adult patients who underwent left-sided or segmental colorectal resection with primary anastomosis for both benign and malignant indications (excluding right colectomy, abdominoperineal resection, TaTME, Hartmann’s procedure, and stoma-protected cases) at Békés County Central Hospital, Gyula, Hungary, between January 2018 and December 2024. AL was defined according to ISREC criteria, with only clinically relevant grade B or C leaks recorded as events. The main exposure was cumulative surgeon experience (log2-transformed). The primary analysis used a multivariable generalized estimating equation (GEE) model clustered by surgeon, adjusted for operative time, surgical approach, conversion, wound infection, and resected segment. Eight surgeons participated, with cumulative experience ranging from 50 to 600 cases. Results: Among the 315 patients included, the median age was 68 years, with a male predominance (61.0%); most cases involved malignant pathology (82.9%) and at least one comorbidity (73.3%). The rectosigmoid was the most frequently resected segment (49.8%), and an open approach was used in 58.7% of cases. The overall AL incidence was 7.94% (25/315), with a median onset at postoperative day 5. In the multivariable GEE model, cumulative surgeon experience was not significantly associated with AL risk (OR per doubling 1.12; 95% CI 0.73–1.72; p = 0.597), nor was operative time (OR per 10 min 1.03; p = 0.294). Wound infection was the only variable significantly associated with AL (OR 3.48; 95% CI 1.06–11.44; p = 0.042), although its temporal relationship with AL could not be established from the available data. AL rates by experience category were 8.9%, 7.5%, and 7.9% for surgeons with <100, 100–199, and ≥200 cases, respectively (p = 0.913). AL was associated with a significantly prolonged hospital stay (median 17 vs. 7 days, p < 0.001) regardless of surgical approach. Conclusions: Cumulative surgeon experience was not independently associated with AL risk in the selected sample of colorectal resections with primary anastomosis in this single-center, mid-volume setting. Wound infection emerged as the only variable significantly associated with AL, although its temporal relationship with AL could not be determined and several established confounders, including anastomotic height, BMI, ASA class, and emergency status, were unavailable for adjustment. Considerable inter-surgeon variability was observed irrespective of case volume. These findings highlight the complexity of AL risk and the need for prospective multicenter studies with comprehensive risk adjustment.