Ureteropelvic junction obstruction

• Male > female
• Etiology: malformation of ureter
• Causes hydronephrosis in utero
  • Most common cause of abdominal mass in children
  • In most cases hydronephrosis is diagnosed in utero by US
• Diagnosis
  • Ultrasound
  • IV urography
• Treatment
  • Observation in asymptomatic cases
  • Surgical correction if symptomatic