Differential Diagnosis for Hydronephrosis with Pain without Stone or Infection

Single Most Likely Diagnosis

• Ureteropelvic junction (UPJ) obstruction: This condition is a common cause of hydronephrosis without stone or infection, often presenting with intermittent flank pain due to the obstruction of the ureteropelvic junction.

Other Likely Diagnoses

• External ureteral compression: Compression of the ureter by external structures such as tumors, lymph nodes, or blood vessels can cause hydronephrosis and pain.
• Ureteral stricture: A narrowing of the ureter can obstruct urine flow, leading to hydronephrosis and pain.
• Congenital anomalies: Anomalies like horseshoe kidney or ectopic ureter can cause hydronephrosis due to abnormal anatomy.

Do Not Miss Diagnoses

• Malignancy (e.g., renal cell carcinoma, transitional cell carcinoma): Although less common, malignancies can cause hydronephrosis and pain by obstructing the urinary tract.
• Retroperitoneal fibrosis: A rare condition characterized by fibrosis in the retroperitoneum that can encase and obstruct the ureters.
• Vascular causes (e.g., nutcracker phenomenon): Compression of the left renal vein between the aorta and superior mesenteric artery can cause left flank pain and hydronephrosis.

Rare Diagnoses

• Primary megaureter: A rare congenital condition where the ureter is dilated, potentially causing hydronephrosis.
• Prune belly syndrome: A rare congenital disorder characterized by absence of abdominal muscles, undescended testes, and urinary tract anomalies, including hydronephrosis.
• Eosinophilic granuloma: A rare condition that can cause ureteral obstruction and subsequent hydronephrosis.