Ureteropelvic Junction Obstruction

  • Etiology: intrinsic narrowing of ureter or extrinsic compression of ureter from a crossing blood vessel
  • Imaging: extremely dilated renal collecting system without seeing a dilated ureter
  • Clinical: hydronephrosis is most common cause of a renal mass in a neonate and ureteropelvic junction obstruction is the most common cause of hydronephrosis, can present as flank pain in teen after large fluid challenge or as large renal injury after minor blunt abdominal trauma

Cases of Ureteropelvic Junction Obstruction

IVP of ureteropelvic junction obstruction
4 hour delayed image from an IVP exam shows an extremely dilated left renal collecting system. The left ureter is not seen.
US of ureteropelvic junction obstruction
Sagittal US of the right kidney (upper left) and left kidney (upper right) shows bilateral mild to moderate hydronephrosis. AP image from the excretory phase of an intravenous pyelogram shows bilateral moderately dilated renal collecting systems with normal appearing bilateral ureters.
Sagittal US of the left and right kidneys shows echogenic medullary pyramids bilaterally and mild right hydronephrosis.