Differential Diagnosis for Right-Sided Flank Pain, Tenderness, Hydronephrosis, and Proximal Ureter Dilation

• Single Most Likely Diagnosis
  • Ureteral Stone (Nephrolithiasis): This condition is the most common cause of acute flank pain and hydronephrosis due to obstruction of the ureter. The presence of proximal ureter dilation supports this diagnosis, as stones can cause obstruction leading to dilation of the ureter proximal to the stone.
• Other Likely Diagnoses
  • Ureteropelvic Junction (UPJ) Obstruction: A congenital condition where the ureter and renal pelvis do not properly connect, leading to obstruction and subsequent hydronephrosis. Symptoms can include flank pain and tenderness.
  • Pyelonephritis or Kidney Infection: While not directly causing ureter dilation, severe infection can lead to inflammation and subsequent obstruction. The presence of hydronephrosis could be secondary to the infection.
• Do Not Miss Diagnoses
  • Retroperitoneal Hemorrhage or Bleeding: Although less common, a retroperitoneal bleed can cause flank pain and hydronephrosis due to external compression of the ureter. Missing this diagnosis could be life-threatening.
  • Malignancy (e.g., Renal Cell Carcinoma, Ureteral Cancer): Tumors can obstruct the ureter, leading to hydronephrosis. While less likely, missing a malignancy could have severe consequences.
• Rare Diagnoses
  • Retroperitoneal Fibrosis: A rare condition characterized by the proliferation of fibrous tissue in the retroperitoneum, which can encase and obstruct the ureters, leading to hydronephrosis.
  • Congenital Anomalies (e.g., Duplex Ureter, Ectopic Ureter): These anomalies can lead to obstruction and hydronephrosis but are less common causes of acute flank pain in adults.
  • Inflammatory Conditions (e.g., Sarcoidosis, Tuberculosis): These can cause ureteral obstruction and subsequent hydronephrosis but are rare and often associated with systemic symptoms.