What is Nutcracker Disease?

Nutcracker syndrome, also known as left renal venous compression syndrome or nutcracker phenomenon, refers to a long-unidentified disease in which the left renal vein is squeezed and formed in the angle formed by the abdominal aorta and the superior mesenteric aorta during the process of returning to the inferior vena cava, resulting in hematuria, proteinuria, left flank and abdominal pain, and varicose veins. The disease is more common in children and adolescents. Most patients are tall. The clinical symptoms are mainly asymptomatic macroscopic hematuria or microscopic hematuria. Some may have renal varicose veins and spermatic varicose veins, proteinuria, hypertension and low back pain.

The diagnostic criteria for this disease are: bleeding in one kidney; the shape of the urine red blood cells is non-tubular; the calcium metabolism in the urine is normal; cystoscopy shows bleeding or urinary incontinence from the left urethral orifice; abdominal color Doppler ultrasound or CT scan shows dilation of the left renal vein, etc.

Ultrasound has significant advantages in the diagnosis of Nutcracker syndrome. Color Doppler ultrasound can clearly display the anatomical conditions of the abdominal aorta, superior mesenteric aorta and left renal vein. The largest inner diameter of the left renal vein can be found in different cross-sections with accurate measurements. At the same time, the changes in the intersection angle between the superior mesenteric aorta and the abdominal aorta can be observed and accurately measured. B-ultrasound blood velocity provides more accurate changes in hemodynamics, which is helpful for the diagnosis of this disease. Color Doppler ultrasound examination can also detect hematuria caused by congenital malformations, trauma, tumors, stones, infectious diseases and abnormal vascular anomalies.

MRA can clearly display the three-dimensional relationship between the renal vein and the peripheral blood vessels. The intersection angle of the superior mesenteric aorta from the pulmonary artery and the distance between them are of great use value for diagnosis, and the left and right diameters of the left renal vein are of practical reference significance for diagnosis.