URETEROVESICAL JUNCTION OBSTRUCTION (UVJ)

UVJ obstruction is the second most common cause of hydronephrosis, accounting for 23% of cases (1).

ETIOLOGY

• Distal ureteral obstruction is usually functional resulting in a primary megaureter. Ureteral atresia is less commonly present.

CLASSIFICATION

Link to Classification Of Hydronephrosis

ULTRASOUND

• Usually unilateral (rarely bilateral).
• Hydronephrosis with a dilated ureter seen as a serpiginous anechoic cystic structure in the abdomen and retrovesical space (2).
  The ureter is retroperitoneal, and therefore appears as a fluid- filled structure adjacent to the fetal spine when dilated.

• Normal bladder filling and emptying is present.

• Coexisting anomalies include vesicoureteral reflux, ureteropelvic junction stenosis and multicystic renal dysplasia.
• Amniotic fluid is usually normal unless the contralateral kidney is also obstructed.

Video clip of Hydronephrosis – obstruction at VU junction

REFERENCES

1. Brown T, Mandell J, Lebowitz RL. Neonatal hydronephrosis in the era of sonography. AJR 1987;148:959.
2. Montana MA, Cyr DR, Lenke RR et.al. Sonographic detection of fetal ureteral obstruction. AJR 1985;145:595.