Comparison of different modalities for the diagnosis of parastomal hernia: a systematic review

Purpose Parastomal hernia (PSH) is a common complication following stoma formation. The incidence of PSH varies widely due to several factors including differences in diagnostic modality, observer, definition, and classification used for diagnosing PSH. The aim of this systematic review was to evaluate the diagnostic accuracy of the modalities used to identify PSH. Methods Embase, MEDLINE, Cochrane, Web of Science, and Google Scholar databases were searched. Studies reporting PSH incidence rates detected by two or more different diagnostic modalities or inter-observer variation on one diagnostic modality were included. Article selection and assessment of study quality were conducted independently by two researchers using Cochrane Collaboration's tool for assessing risk of bias. PROSPERO registration: CRD42018112732. Results Twenty-nine studies (n = 2514 patients) were included. Nineteen studies compared CT to clinical examination with relative difference in incidence rates ranging from 0.64 to 3.0 (n = 1369). Overall, 79% of studies found an increase in incidence rate when using CT. Disagreement between CT and clinical examination ranged between 0 and 37.3% with pooled inter-modality agreement Kappa value of 0.64 (95% CI 0.52-0.77). Four studies investigated the diagnostic accuracy of ultrasonography (n = 103). Compared with peroperative diagnosis, CT and ultrasonography both seemed accurate imaging modalities with a sensitivity of 83%. Conclusion CT is an accurate diagnostic modality for PSH diagnosis and increases PSH detection rates, as compared with clinical examination. Studies that specially focus on the diagnostic accuracy are needed and should aim to take patient-reported outcomes into account. A detailed description of the diagnostic approach, modality, definition, and involved observers is prerequisite for future PSH research.