Parastomal hernia: clinical and radiological definitions

Parastomal hernia is a frequent complication after stoma formation. No consistent definition of parastomal hernia has been used in previous studies using clinical examination or computed tomography (CT) scan. The correlation between herniation rates found with clinical examination and CT scan has been poor. A definition of parastomal hernia with clinical examination that correlates with findings from CT scan should be sought.

Parastomal hernia, was with surgeons' clinical examination, defined as any protrusion in the vicinity of the stoma with the patient straining in a supine and an erect position. A new CT scan method was developed with the patient examined in the prone position. Radiologists defined herniation as any intra-abdominal content protruding beyond the peritoneum or the presence of a hernia sac. The correlation between investigators and methods were estimated by calculating Fleiss' Kappa values.

Twenty-seven patients were assessed by three surgeons and three radiologists. For the surgeons, the Kappa value was 0.85. For the radiologists, it was 0.85 with CT scan in the prone position and 0.82 in the supine position. For the surgeons and radiologists collectively, the Kappa value was 0.80 for CT scan in the prone position and 0.63 in the supine position.

With the new CT scan method examining patients in the prone position, the clinical and radiological definitions were highly reproducible and correlated strongly between methods and raters. With the strong correlation between clinical and radiological assessments, clinical examination alone is sufficient as follow-up. Conventional CT scan with the patient supine is not a reliable tool for diagnosing parastomal hernia.