Diagnostic Accuracy of Abdominal Ultrasound for Diagnosis of Acute Appendicitis: Systematic Review and Meta-analysis.

Background: To determine the diagnostic accuracy of abdominal ultrasound (US) for the diagnosis of acute appendicitis (AA), in terms of sensitivity, specificity and post-test probabilities for positive and negative result.

Methods: A systematic search of MEDLINE, Embase, The Cochrane library and Science Citation Index Expanded from January 1994 to October 2014 was performed. Two authors independently evaluated studies for inclusion, extracted data and performed analyses. The reference standard for evaluation of final diagnosis was pathohistological report on tissue obtained at appendectomy. Summary sensitivity, specificity and post-test probability of AA after positive and negative result of US with corresponding 95% confidence intervals (CI) were calculated.

Results: Out of 3306 references identified through electronic searches, 17 reports met the inclusion criteria, with 2841 included participants. The summary sensitivity and specificity of US for diagnosis of AA were 69% (95% CI 59-78%) and 81% (95% CI 73-88%), respectively. At the median pretest probability of AA of 76.4%, the post-test probability for a positive and negative result of US was 92% (95% CI 88-95%) and 55% (95% CI 46-63%), respectively.

Conclusions: Abdominal ultrasound does not seem to have a role in the diagnostic pathway for diagnosis of AA in suspected patients. The summary sensitivity and specificity of US do not exceed that of physical examination. Patients that require additional diagnostic workup should be referred to more sensitive and specific diagnostic procedures, such as computed tomography.