The hemorrhagic trade-off: anastomotic bleeding in the era of enhanced recovery and combined bowel preparation

Aim Enhanced Recovery After Surgery (ERAS) pathways and combined mechanical and oral antibiotic bowel preparation (MBP + OAB) have improved outcomes in colorectal surgery by reducing infectious complications and anastomotic leakage. However, their impact on anastomotic bleeding (AB) remains unclear. Method We conducted a prospective observational study including consecutive patients undergoing elective colorectal resection with primary anastomosis between 2012 and 2025 at a tertiary center. A modified ERAS pathway incorporating systematic MBP + OAB was progressively implemented. Predictors of AB were identified using Elastic Net penalized regression and multivariable logistic regression. Temporal trends were assessed using interrupted time series and change point analyses. Result A total of 1547 patients were included. Following implementation of the modified ERAS pathway, anastomotic leakage decreased (10.7% vs. 7.9%), whereas AB increased significantly (2.1% vs. 5.8%, p < 0.001). Most bleeding events were minor and did not require transfusion or invasive treatment. In multivariable analysis, MBP + OAB was associated with increased AB (OR 3.74, 95% CI 1.98–7.05), and ileocolic anastomosis was also associated with increased risk (OR 2.26, 95% CI 1.22–4.18). Temporal analyses identified a structural change after formal standardization of MBP + OAB, followed by a sustained increase in AB incidence. However, severe anastomotic leakage, reoperation, and postoperative mortality decreased. Conclusion Implementation of systematic MBP + OAB was associated with an increased incidence of predominantly minor anastomotic bleeding. Ileocolic anastomosis was also associated with increased bleeding risk, whereas perioperative DOAC therapy may contribute to risk in selected patients. Surgical teams should factor these modifiable and anatomical elements into risk stratification models.