Ultrasonography of flank pain in the emergency department: renal cell carcinoma as a diagnostic concern.

Acute flank pain is a common emergency department presenting symptom, and bedside ultrasound is being used increasingly in its evaluation. Emergency renal ultrasonography concentrates on the focused presence or absence of hydronephrosis as is often seen in patients with acute flank pain secondary to renal colic. We present three cases in which other abnormal sonographic signs not commonly taught prompted further investigation, revealing renal cell carcinoma. Baseline knowledge of sonographic characteristics of tumors will benefit the occasional emergency patient who has unsuspected renal carcinoma.