Influence of Time Interval Between the Two Stages of Delayed Coloanal Anastomosis on the Risk of Anastomotic Leakage: Multicenter Study from the GRECCAR Group

BACKGROUND: The optimal time interval between the two surgical stages of a delayed coloanal anastomosis has never been investigated. OBJECTIVE: Assess the influence of time interval on anastomotic leakage occurrence DESIGN: Retrospective cohort study. SETTINGS: Multicentric study (30 colorectal centers). PATIENTS: All patients who underwent delayed coloanal anastomosis (2010-2021). MAIN OUTCOME MEASURES: anastomotic leakage in relation to the time interval between the two surgical stages. RESULTS: A total of 506 patients (female: 42%, median age: 62.1 years) underwent delayed colo-anal anastomosis, 63% immediately after a low anterior resection (primary delayed coloanal anastomosis) and 37% after failure of primary pelvic surgery as a salvage procedure (salvage delayed coloanal anastomosis). The main reasons for salvage delayed coloanal anastomosis were chronic pelvic sepsis (42%) and rectovaginal fistula (38%). The mean time interval between two stages was 8.6 ± 3.8 days, ranging from 1 to 22 days. In the entire cohort, the incidence of anastomotic leakage was 18% (89/506, 95 CI [14%, 21%]) and time interval did not affect the occurrence of anastomotic leakage ( p = 0.529). In sub-group analysis, anastomotic leakage risk was not associated with time interval among primary delayed coloanal anastomosis patients ( p = 0.579) whereas it was for salvage delayed coloanal anastomosis patients ( p = 0.013). In salvage delayed coloanal anastomosis patients, multivariate analysis showed that a longer time interval (adjusted OR=0.89, 95 CI [0.81-0.98], p = 0.035) and surgery in centers performing ≥4 delayed coloanal anastomosis per year (adjusted OR = 0.07, 95 CI [0.01-0.36], p = 0.011) were significantly linked to a lower risk of anastomotic leakage. Each additional day between the two salvage delayed coloanal anastomosis procedures was estimated to reduce the risk of anastomotic leakage by 11%. LIMITATIONS: The retrospective design. CONCLUSIONS: In the context of primary delayed coloanal anastomosis, increasing the time interval between the two stages of delayed coloanal anastomosis does not influence the risk of anastomotic leakage. For salvage delayed coloanal anastomosis, extending the time interval significantly reduces the risk of anastomotic leakage.