An easily missed diagnosis: flank pain and nutcracker syndrome.

A 27-year-old woman presented to her primary care doctor's office with left flank pain. CT of the abdomen showed an isolated left renal vein thrombus. The clot was initially attributed to her oral contraceptive use; however, closer inspection of CT images revealed nutcracker phenomenon (compression of the renal vein between the superior mesenteric artery and abdominal aorta). Intravascular ultrasound imaging confirmed the diagnosis. Nutcracker syndrome is a rare condition, which if left untreated may cause damage to the left kidney. Although under diagnosed, there are several treatment options available ranging from simple surveillance to surgical resolution.