Delayed Loop Ileostomy Reversal Increases the Risk of Colitis and <i>Clostridium difficile</i> Infection

BACKGROUND: Temporary loop ileostomy formation is a routine procedure performed to protect distal colorectal anastomosis. Traditionally, the ideal timing of ileostomy reversal is believed to fall between 3 and 6 months. It has been suggested that delayed reversal increases the risk of complications. Our study looks to demonstrate the relationship between delayed reversal and its associated risks in a real-world setting. METHODS: This is a retrospective cohort study conducted at Monash Health, analysing patients who underwent loop ileostomy reversal from May 2016 to December 2023. Main outcome measures include incidence of post-reversal complications, including colitis, Clostridium difficile infection, anastomotic leak, ileus, wound infection and acute kidney injury. Secondary outcome is to investigate the impact of COVID-19 on ileostomy reversal timing. RESULTS: A total of 223 patients were included. The primary indications for initial surgery included cancer (n = 134), inflammatory bowel disease (n = 19) and diverticular disease (n = 29). The median time between initial surgery and ileostomy reversal was 341 days (IQR = 211-530). Post-reversal complications occurred in 65 patients (29.1%). Patients reversed after the pandemic experienced a delay between surgeries (median: 411, IQR = 276-660) compared with those prior (median: 294, IQR = 196-408, p < 0.0001). A statistically significant association was seen between delayed reversal and post-operative complications (OR 1.11, p = 0.020, ROC AUC = 0.588). Ileostomy reversal occurring beyond 134 days (based on the Youden's Index with 90% sensitivity-based cutoff) is associated with increased risk of complications. CONCLUSION: Delayed loop ileostomy reversal is associated with post-operative complications specifically colitis and C. difficile colitis.