The prevalence of parastomal hernia after formation of an end colostomy. A new clinico-radiological classification.

Introduction  Parastomal hernia (PH) is a common complication of end colostomy, found in over 50% of patients. Abdominal computerized tomography (CT) may help diagnosis. The prevalence of PH may be higher than previously reported. We present a new CT classification for use in clinical practice. Method  A cross-sectional, descriptive observational study was carried out, assessing the clinical and radiological prevalence of PH in 75 patients with an end colostomy operated on since 1997. Clinical examinations were performed by a single surgeon. Abdominal CTs were assessed by a single radiologist. Results  PH was observed clinically in 33 (44%) of 75 patients and 27 (82%) were symptomatic. Using the classification 0 (Normal), I (Hernial sac containing stoma loop), II (Sac containing omentum), III (Sac containing a loop other than stoma), radiological PH was observed in 35 (47%) patients. Clinical/radiological concordance (Kappa index = 0.4) increased proportionally with sac size. All type-III PHs (n = 9) were symptomatic. The combined prevalence of PH detected by one or other method was 60.8%. Conclusion  Clinical and radiological prevalence of PH is high. As there is no gold standard for PH detection, we recommend a combination of the two methods. A new classification for use in clinical practice is proposed.