RADIOLOGY: GENITOURINARY: GU: Case# 32934: RETROCAVAL URETER. The patient is a 29 year old female with the history of breast cancer status post radiation therapy and chemotherapy. The abdominal scan is compared to the earlier abdominal CT. Incidental note is made of a retrocaval right ureter. Retrocaval ureter is an anomaly in which the right ureter passes behind the inferior vena cava at the level of L3 or L4 and then exits anteriorly between the aorta and vena cava returning to its normal position. It is the result faulty embryogenesis of the inferior vena cava with abnormal persistence of the right subcardinal vein anterior to the ureter instead of the right supracardinal vein posterior to the ureter. is