EP2023 - Contralateral Metachronous Diverticulitis After Previous Colon Resection: A Random Event or a High-Risk Phenotype?

Purpose/Background: Recurrence of diverticulitis after segmental colon resection is uncommon (2-6%) and usually occurs near the initial site, typically mild and managed non-operatively. In contrast, contralateral, metachronous diverticulitis-occurring in a non-overlapping segment on the opposite side-is exceedingly rare and poorly characterized. This study aimed to determine its incidence and clinical features to assess whether limited segmental resection at the index surgery remains justified.

Methods/Interventions: This retrospective cohort study comprised adult patients with a prior colectomy for diverticulitis in a single segment between January 1, 2009, and August 31, 2025, who subsequently underwent resection for contralateral, metachronous diverticulitis at a single referral center. Patients with multifocal diverticulitis at index surgery have been excluded. Demographic, clinical, operative, and outcome data were extracted from the electronic health records. Descriptive statistics were used to summarize baseline characteristics, surgical management, and postoperative outcomes.

Results/Outcomes: Of 5,139 sigmoid colectomies and 91 right hemicolectomies for unilateral diverticulitis, eight patients met inclusion criteria, resulting in an incidence of 0.2%. Median age at first surgery was 59 years (IQR 54-66.8), mostly male, with median BMI 31.5 kg/m² (IQR 27.6-31.7). Five had COPD or asthma, three chronic kidney disease, and three IBD (two on immunosuppressants). Seven showed pancolonic diverticulosis at index surgery; four presented emergently and five had complicated disease (Hinchey II-IV), including three perforations. Initial procedures were seven sigmoid colectomies and one right hemicolectomy; two presented with fistula. Median hospital stay was 10.5 days (IQR 9.8-13). Three developed postoperative complications, two major (one leak, one reoperation). Median interval to contralateral resection was 60 months (IQR 34-69); three were emergent. Most underwent subtotal colectomy, followed by right hemicolectomy; others had total colectomy, APR, or sigmoid resection. Median stay was 9 days (IQR 7.5-13). Four had postoperative complications, three major; two required reoperation. No patient experienced further episodes of diverticulitis following the second surgical intervention. No 30-day mortality occurred.

Conclusion/Discussion: Contralateral, metachronous diverticulitis requiring surgery is exceedingly rare. Seven patients had pancolonic diverticulosis at the index surgery, indicating a diffuse rather than localized predisposition. Although some had IBD or were immunosuppressed, the small sample size precludes conclusions. Given the rarity of requiring subsequent resection, these findings suggest that surgery at the index event should remain limited to the affected segment, even in patients with pancolonic diverticulosis.

Table 1. Clinical Characteristics of Patients Undergoing Surgery for Contralateral, Metachronous Diverticulitis