The aorta, the body’s main artery originates from the heart; in the tummy region it gives off several other arteries that supply organs with blood. The inferior vena cava (IVC) returns blood from the lower body back to the heart. In the tummy, the aorta and IVC lie side by side; the aorta lies on the IVC’s left side.
One of the aorta’s tummy branches is the superior mesenteric artery (SMA) which supplies the intestines with blood.
Blood returning from the left kidney (within the left renal vein) must cross in front of the aorta to reach the IVC because of the relationship between the aorta and IVC - the aorta lies on the IVC’s left side.
Rarely, the left renal vein can become compressed between the SMA and aorta causing it to dilate. The SMA and aorta in this situation have been likened to the handles of a nutcracker squashing a nut which in this case is the left renal vein – nut cracker phenomenon (renal vein entrapment syndrome).
When the nutcracker phenomenon causes disease such as blood in the urine, tummy pain, the situation is then known as the nutcracker syndrome.
Reference:Navarro J, Azua-Romeo J, Tovar MT, Lopez JA. Nutcracker syndrome: a rare anatomic variant. BJUI, 2012 DOI: 10.1002/BJUIw-2011-092-web Go to reference
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