Xanthogranulomatous Pyelonephritis: A Complicated Febrile Urinary Tract Infection Detected by Point-of-Care Ultrasound in the Emergency Department.

BACKGROUND: Febrile urinary tract infections (UTIs) include a spectrum of pathologies from uncomplicated pyelonephritis to urosepsis, including xanthogranulomatous pyelonephritis (XGP). Most febrile UTIs are treated with antibiotics alone, but studies indicate nearly 12% of cases of presumed simple pyelonephritis require emergent urologic intervention. How to identify these individuals, while limiting unnecessary advanced imaging and delays in diagnosis, challenges all emergency providers. We review the diagnosis and management of XGP, as well as the evidence regarding the role of renal ultrasound in the identification of complicated presentations of febrile UTIs. CASE REPORT: We present a case of XGP, a complicated febrile UTI requiring immediate urologic intervention, diagnosed by point-of-care ultrasound. A 40-year-old female presented in severe sepsis and complaining of flank pain. Prompt bedside ultrasound demonstrated hydronephrosis, expediting definitive urologic treatment via percutaneous nephrostomy tube placement. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: With a mortality rate exceeding 40%, obstructed pyonephrosis requires prompt decompression. Given its exceptional sensitivity for identifying hydronephrosis and ability to detect abscesses and emphysematous changes, we advocate a point-of-care ultrasound-first approach to screen for cases of complicated febrile UTIs in order to expedite treatment and limit radiation in uncomplicated presentations.