Left renal vein entrapment syndrome: nutcracker syndrome!

Nutcracker syndrome (NCS) is a rare vascular compression disorder that involves compression of the left renal vein most commonly between the aorta and the superior mesenteric artery (SMA), although variations exist. It is associated with the formation of the left renal vein from the aortic collar during the 6th-8th week of gestation and abnormal angulation of the SMA from the aorta. Collateralisation of venous circulation including mainly the left gonadal vein and the communicating lumbar vein are the most significant effects. It has a female predilection occurring in the third to fourth decade and it tends to be diagnosed earlier in men. Affected individuals may present with a myriad of symptoms such as haematuria, left flank pain and proteinuria. As patients often present with these non-specific symptoms to primary care, knowledge of NCS is essential. The diagnosis can be rendered with Doppler ultrasonography, retrograde venography, CT angiography, intravascular ultrasound and magnetic resonance angiography. The authors describe the case of a 39-year-old woman with a low body mass index (BMI) presenting with generalised abdominal and flank pain as well as chronic microcytic anaemia. Physical examination findings were suggestive of biliary or renal colic. Laboratory investigations confirmed her anaemia (haemoglobin 88 g/L, mean corpuscular volume (MCV) 72 fL), but were otherwise unremarkable. Urinalysis showed proteinuria and haematuria. However, ultrasonography was unremarkable with a normal gallbladder and no evidence of calculi. Her CT scan showed marked compression of the left renal vein between the aorta and the SMA (nutcracker phenomenon), with upstream left renal, left gonadal and left lumbar vein dilatation. She was managed conservatively. This paper provides an overview of the aetiology, embryology, clinical manifestations, imaging modalities and management of NCS.