Endoscopic classification of Meckel's diverticulum in adults: a multicenter retrospective study

Meckel's diverticulum (MD) is the most common congenital gastrointestinal malformation. Balloon-assisted enteroscopy (BAE) permits direct visualization in adults, but no standardized endoscopic classification exists. We developed an endoscopic framework for adult MD and evaluated its clinical utility and association with disease severity.

In this multicenter retrospective study, we enrolled 226 symptomatic adults with BAE-diagnosed MD at three tertiary centers from May 2007 to May 2024. Based on morphology and mucosal characteristics, MD was assigned to three primary categories: Type S, an endoscopically quiescent smooth mucosa pattern; Type A, abnormal mucosa or high-risk structural features; and Type U, lesions that could not be adequately characterized. Inverted MD was recorded as Type I, a morphological subtype within the Type A spectrum. Reproducibility of the core Type S-versus-Type A distinction was assessed using Fleiss' and Cohen's kappa statistics among six external experts and the lead author. Multivariable logistic regression evaluated factors associated with severe disease presentation.

The Type A spectrum included 159 patients, comprising 155 non-inverted Type A cases and 4 Type I cases. Type S was identified in 64 patients, and Type U in 3 patients. Interobserver agreement for the core Type S-versus-Type A distinction was substantial (Fleiss' kappa = 0.7936). Multivariate analysis showed that Type A (including Type I) was the only factor independently associated with severe disease presentation (OR: 5.550; 95% CI 2.693-11.439; P < 0.001).

The A-S framework provides a concise morphological approach for symptomatic adults with BAE-diagnosed MD. It distinguishes lesions for which surgical consultation and resection should be considered from those generally suitable for conservative management, while Type U warrants further evaluation. Prospective external validation is required.