Retrocaval ureter presenting with hydronephrosis: A case report of rare entity in Nepal.

Hydronephrosis, characterized by the dilation of the renal pelvis and calyces, often results from obstructive uropathy, commonly due to ureterolithiasis. However, rare congenital anomalies, such as a retrocaval ureter (RCU)-where the ureter passes behind the inferior vena cava- can also cause hydronephrosis. This case report describes an 11-year-old male presenting with right-sided flank pain and hematuria. Initial ultrasonography and noncontrast CT revealed right hydronephrosis without ureteral stones. Subsequently, contrast-enhanced CT urography found an abnormality in the course of the right ureter behind the inferior vena cava. He was diagnosed with right retrocaval ureter with hydronephrosis, and managed by surgical resection of the retrocaval segment and uretero-ureteral anastomosis. The postoperative course was uneventful. RCU usually presents in the third or fourth decade of life, however, it should be in the differential diagnosis of hydronephrosis in the pediatric population. The diagnosis of RCU is often delayed and missed till advanced imaging like CT urography is sought for unexplained hydronephrosis. If left untreated, it may lead to chronic renal failure. Therefore, emphasis should be placed on timely diagnosis and management of retrocaval ureter.