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Virtual Pediatric Hospital: Paediapaedia: Ureteropelvic Junction Obstruction (UPJ) Paediapaedia: Genitourinary Diseases

Ureteropelvic Junction Obstruction (UPJ)

Michael P. D'Alessandro, M.D.
Peer Review Status: Internally Peer Reviewed

Clinical Presentation:
Complains of intermittent flank pain or recurrent urinary tract infections. Can have hematuria after minor abdominal trauma. May present as an abdominal mass. Most commonly presents after 5 years old.

Intrinsic narrowing of the ureteropelvic junction. The etiology of this narrowing is due to abnormalities in longitudinal muscle development or an aberrant crossing vessel. Twenty to thirty percent of cases are bilateral.

Not applicable

Imaging Findings:
On IVP a rim of dense parenchyma around lucent dilated calyces during the nephrogram phase (rim sign) is seen. As contrast is slowly excreted into the collecting system it is diluted by urine retained in the obstructed system. Later the accumulation of contrast in collecting tubules can produce curvilinear calyceal densities (calyceal crescents).

Ultrasound shows a dilated anechoic renal pelvis surrounded by communicating dilated calyces in the kidney.


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