Diagnosis of UPJ Obstruction

UPJ obstruction that causes hydronephrosis is usually diagnosed by prenatal ultrasound. Neonatal patients suspected to have this condition are evaluated for the obstruction using renal ultrasound. Other imaging tests may also be required.

Other diagnostic tests used to evaluate kidney function and determine the severity of the blockage include the following:

  • Creatinine, BUN (blood urea nitrogen), and electrolyte levels
  • Complete blood count (CBC)
  • Diuretic renal scan
  • Urine culture
  • Voiding cystourethrogram (VCUG; used to rule out vesicoureteral reflux)

In diuretic renal scan, a small amount of radioactive substance is injected into a vein and kidney function is assessed using scanned images of the organ as it removes the substance from the blood.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 09 Jun 1998

Last Modified: 13 Oct 2015