Integration of Clinical Risk Factors With Radiological Metrics Associated With PSH : The Impact of Stoma Site Features, Obesity and Muscle Atrophy

AIM: To determine our incidence of parastomal hernia (PSH) after end colostomy formation and to integrate clinical and novel computed tomography (CT)-derived stoma-site risk factors. METHODS: We performed a retrospective study of adults undergoing operations resulting in permanent end colostomy at Dunedin Hospital, New Zealand (2009-2022), who had at least one pre- or post-operative abdominal CT scan. PSH and risk factors were identified clinically from electronic medical records or radiologically using the Moreno-Matias classification. Radiological variables included abdominal wall width, rectus muscle-to-subcutaneous fat ratio, rectus density, intraperitoneal area, aperture size and stoma location within the rectus muscle; univariable and multivariable logistic regression identified independent predictors of PSH. RESULTS: Among 217 patients, 64 (29%) were diagnosed with PSH, with approximately half symptomatic. Univariable analysis identified six risk factors: body mass index, diabetes, abdominal wall width, abdominal wall muscle-to-fat ratio, fascial defect diameter and stoma position within the rectus. In adjusted analyses, larger defect diameter (OR: 3.24 per 1 cm increase, 95% CI; 1.96-5.91), abdominal wall muscle-to-fat ratio (OR: 0.68 per 10% increase, 95% CI: 0.49-0.88) and lateral stoma position (OR: 2.79, 95% CI: 1.03-7.86) were independently associated with PSH. CONCLUSION: Combining clinical information with CT-based morphological assessment identified aperture size and abdominal wall muscle-to-fat ratio as key risk factors, and precise central transrectus stoma placement as a risk factor of interest. These findings may inform preoperative risk stratification, technical optimisation of stoma construction and selection of patients for prophylactic interventions.