Nutcracker syndrome in pregnancy: a worrying presentation of a benign condition.

Nutcracker syndrome is a very rare cause of haematuria that results from mechanical obstruction of the left renal vein between the descending aorta and the superior mesenteric artery. The compression leads to development of an extensive collateral venous drainage system involving the left gonadal capsular, suprarenal, lumbar, azygous and peri-ureteral veins. The appearance resembles a nut caught between the jaws of a nutcracker and thus the name nutcracker syndrome. It was first decribed by the anatomist Grant in 1937 [1]. Haematuria results when the thin walled septum separating the varicosities from the urinary collecting system ruptures. This may occur in the presence of a reduced angle between the aorta and the superior mesenteric artery or due to increase in aortic diameter that occurs during pregnancy. The most common presentation is intermittent microscopic haematuria, while gross hematuria and left flank pain secondary to the passage of ureteral blood clots is rare. Symptoms of pelvic venous congestion (chronic pelvic pain, dyspareunia and dysmenorrhea) may also occur in females [2, 3].