An 18-year-old man comes to the clinic due to hematuria and intermittent left flank pain of several months duration. He has no history of trauma or sexually transmitted diseases and no associated fever or dysuria. Examination reveals a soft abdomen with normal bowel sounds and no localized tenderness. Urinalysis confirms 3+ blood but no white blood cells, crystals, or organisms. Contrast-enhanced CT scan shows no abnormalities in the ureters or kidneys but does reveal compression of the left renal vein between the superior mesenteric artery and the aorta. Which of the following is most likely to develop due to the vascular abnormality seen in this patient?

Question

An 18-year-old man comes to the clinic due to hematuria and intermittent left flank pain of several months duration.  He has no history of trauma or sexually transmitted diseases and no associated fever or dysuria.  Examination reveals a soft abdomen with normal bowel sounds and no localized tenderness.  Urinalysis confirms 3+ blood but no white blood cells, crystals, or organisms.  Contrast-enhanced CT scan shows no abnormalities in the ureters or kidneys but does reveal compression of the left renal vein between the superior mesenteric artery and the aorta.  Which of the following is most likely to develop due to the vascular abnormality seen in this patient?

Quizplus · Accepted Answer

11ec160b_3568_e24d_9249_e5792cf84242_MD0001_00 The right renal vein is a relatively short structure and runs anterior to the right renal artery before joining the inferior vena cava (IVC). The right gonadal vein also drains directly to the IVC. In contrast, the left renal vein is significantly longer and runs posterior to the splenic vein before crossing the aorta beneath the superior mesenteric artery. The left gonadal vein joins the left renal vein upstream of where it crosses the aorta and does not enter the IVC directly. The pressure within the left renal vein is often higher than on the right due to compression between the aorta and the superior mesenteric artery ("nutcracker effect"). Pressure in the left renal vein can also be elevated due to compression from a left-sided abdominal or retroperitoneal mass. Persistently elevated pressure in the left renal vein can cause flank or abdominal pain, along with gross or microscopic hematuria (left renal vein entrapment syndrome). Increased pressure in the left gonadal vein results in valve leaflet failure and varices of the testicular pampiniform plexus (varicocele). (Choices A, C, and D) Esophageal varices, rectal varices, and periumbilical venous distension are signs of portal venous hypertension. The renal veins are not part of the portal system. (Choice B) Unilateral left-sided ankle swelling can result from many causes, including obstruction of the left common iliac vein, left external iliac vein, left femoral vein, or any of the other major veins of the left leg. Educational objective: Pressure in the left renal vein may become elevated due to compression where the vein crosses the aorta beneath the superior mesenteric artery. This "nutcracker effect" can cause hematuria and flank pain. Pressure can also be elevated in the left gonadal vein, leading to formation of a varicocele. __________ References: Nutcracker syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/25374822)

An 18-Year-Old Man Comes to the Clinic Due to Hematuria