Emergency Physician-Performed Point-of-Care Ultrasound of a Renal Mass.

Emergency physicians (EPs) frequently integrate point-of-care ultrasound (POCUS) into the initial bedside evaluation of patients presenting to the emergency department with acute flank pain. A POCUS-first diagnostic approach can allow EPs to promptly assess for life-threatening pathologies of the aorta and gallbladder. POCUS is also a critical bedside tool to determine renal causes of acute flank pain, such as hydronephrosis in the setting of nephrolithiasis, subcapsular hematomas, renal abscesses, pyelonephritis, and renal masses. This report illustrates a case in which EP-performed POCUS led to the incidental diagnosis of a malignant renal mass in a patient presenting with flank pain. We review the specifics of the ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) Bosniak classification system used by radiologists for risk stratification of cystic renal masses (CRMs).