The role of emergency ultrasound for evaluating acute pyelonephritis in the ED

Background: Controversy remains over the imaging method of choice for evaluating acute pyelonephritis (APN) in the emergency department (ED). Objective: The aim of the study was to determine the efficacy of ultrasound in the diagnosis and management of patients presented to the ED with APN. Methods: This was a retrospective study of prospectively collected data. A cohort of ED patients diagnosed as APN were prospectively registered, and their medical records were then retrospectively reviewed for the presence of complications (admitted >14 days, admission to intensive care unit, or received invasive procedures), significant abnormalities (hydronephrosis, polycystic kidney diseases, renal abscess, emphysematous pyelonephritis), and mild abnormalities (cysts, stones, swelling). Results: The study included 243 patients. Most of the patients received one or more renal imaging studies (n = 206) and 39.5% of which were considered abnormal. The rates of significant abnormalities on different imaging methods were Kidney-ureter-bladder (KUB), 16.3%; emergency ultrasound (EUS), 39.6%; combination of KUB and EUS, 56.6%; and computed tomography, 58.8%. Factors contributed to complicated APN were elderly, male, a history of preexisting renal diseases, current use of catheters, previous renal calculi, and diabetes mellitus. Significant abnormalities can be identified by EUS in 61% of patients with complicated APN. In fact, the presence of significant sonographic abnormalities effectively diverted 34.3% of patients to receive surgical interventions (percutaneous nephrostomy, abscess aspiration, ureteroscopic stone manipulation, lithotripsy, or nephrectomy). Conclusion: Structural abnormalities are not uncommon in ED patients with APN. Early assessment of these patients with EUS is likely to have a great impact on their diagnosis and management.