RESUMO
PURPOSE: Our primary aim was to evaluate the use of ultrasound (US) as an initial screening test for diagnosing appendicitis in young adult men. Secondary exploratory analyses included the effects of using US for initial screening in these patients, compared with the use of CT, on radiation exposure, length of stay (LOS), and cost of imaging. METHODS: We retrospectively gathered data from the records of male patients 18-39 years old who had been admitted with appendicitis between June 2006 and September 2011. We investigated the diagnostic tests performed, the patients' characteristics, and the pathologic testing findings and compared the results obtained on US with those obtained on CT. RESULTS: Of 451 included patients, 86 had undergone US initially. Its sensitivity was only 57% (95% confidence interval, 46-67.6), but its positive predictive value was 98% (95% confidence interval, 93.8-100). The mean LOS was significantly shorter for patients who had undergone US only (214 minutes) than it was for those who had undergone CT only (276 minutes; p < 0.001). We estimated a 57% reduction in CT use and radiation exposure if US were to be performed initially; this would lead to a 45% decrease in imaging costs at our institution. CONCLUSIONS: Screening US should be considered first for diagnosing appendicitis because of its high positive predictive value, but even if US results are negative for appendicitis, one should not exclude the possible existence of pathology because US has poor sensitivity in this situation. We speculate that the use of screening US can decrease radiation exposure, imaging costs, and LOS.
