Preureteric vena cava

A preureteric vena cava, also known as a retrocaval ureter, is a rare congenital malformation of the right human ureter, where the ureter passes behind the inferior vena cava, causing compression possibly leading to hydronephrosis. The prevalence of this condition is approximately 1 per 1,000 persons, with males 2-3 times more likely than females to develop the condition. Symptoms often do not manifest until the 20's or 30's.