Spinnaker sail sign

Excerpt

Localized distention of the prostatic urethra proximal to posterior urethral valves (PUVs), as seen on voiding cystourethrography (VCUG) (Fig. 1), has been described as the “spinnaker sail” sign (Fig. 2) [1]. The distended portion of the urethra assumes the characteristic configuration of a spinnaker sail, used for sailing “off the wind.” PUVs are the most common congenital obstructive lesion of the urethra, occurring almost exclusively in male children [2]. PUVs represent a membrane caused by an anterior fusion of two abnormal folds, originating from Wolffian duct remnants, that descend from the verumontanum into the more distal prostatic urethra [2]. PUVs may present as acute urinary obstruction in infancy or in adolescence with renal disease, poor urinary stream, urinary incontinence, or urinary tract sepsis [3]. VCUG is the best imaging technique for the diagnosis of posterior urethral valves. Diagnostic features of PUV include a dilated posterior urethra with an abrupt transition into normal caliber anterior urethra, associated bladder distension with thick irregular bladder wall, and hydroureteronephrosis [2].

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