|History: Newborn infant imaged on day zero. Patient with history of in utero hydronephrosis.|
|Findings: Retroperitoneal ultrasound demonstrates severe dilatation of both renal pelves and calyces and severe dilatation and tortuosity of both ureters. The bladder is markedly distended, measuring 8.0 cm in craniocaudal dimension in this newborn infant. The kidneys themselves demonstrate normal echogenicity and do not show evidence of cystic change to suggest dysplasia. No ascites is present. The posterior urethra is not visualized.|
VCUG initially demonstrates a normal appearing bladder. However, with voiding, patient passes the 1.5 cc balloon from his catheter into his posterior urethra which is markedly dilated. Although he is attempting to void, no contrast passes into the anterior urethra. With attempted voiding, the distal ureters show vesicoureteral reflux into balloon-like dilated distal ureters. The reflux on the right remains only in the distal ureter. The reflux on the left reaches the level of the calyces where contrast is diluted by the large amount of urine present in the dilated system.
|Diagnosis: Posterior urethral valves|
|Discussion: Posterior urethral valves create chronic urethral obstruction due to fusion and subsequent prominence of plicae colliculi, which are normal concentric folds of the urethra. VCUG is the best imaging study to make the diagnosis and can demonstrate the abrupt transition from a markedly dilated posterior urethra to a small bulbous urethra. The valves themselves are not usually visualized. This entity occurs exclusively in males.|
Vesicoureteral reflux is seen in 80% of cases. Urinary ascites can occur. Reflux may be seen into the utricle.
The incidence of posterior urethral valves is 1/8,000- 1/25,000 births.
1/3 present prenatally; 1/3 present in infancy; 1/3 present in childhood. The age of presentation depends on the degree of bladder outlet obstruction.
Patients can develop renal dysplasia, and 30% of patients with posterior urethral valves will eventually develop end stage renal disease.
|References: Amirsys 2008 STATdx Posterior Urethral Valves. Sara M. O'Hara, M.D.|
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Case Number: 17407765Last Updated: 2011-08-01 The reader is fully responsible for confirming the accuracy of this content.
The reader is fully responsible for confirming the accuracy of this content.