Spinning top urethra is non-obstructive posterior urethral dilatation seen on voiding cystourethrography, mainly in females. It was initially considered as an indicator of distal urethral narrowing/stenosis. However, it is now believed to be due to functional discoordinate voiding or bladder instability. Although some women have this appearance of the urethra as a normal variant 4, the finding necessitates a detailed search for a functional voiding disorder.
Children are more commonly affected with higher incidence seen in females. It is more common in females as they have tendency to and are trained to hold urine for longer periods.
Clinical manifestations vary depending on the disorder with daytime and night enuresis, recurrent urinary tract infections, urgency and frequency commonly encountered. Commonly vesicoureteric reflux, non-compliant bladder and behavioural disorders are associated with it.
The underlying pathology of this entity is not clearly known. Initially it was believed to be due to distal urethral narrowing/stenosis while recent literature suggests association of functional voiding disorder with spinning top urethra. The initial belief considered it to be post-stenotic dilatation or a dilated segment between urethral meatus and bladder neck due to voluntary contraction of striated sphincter. It is now believed that the dilatation results from bladder instability, however voiding dysfunction may not necessarily be demonstrated in all such cases.
A congenital bladder neck anomaly may also predispose to spinning top urethra.
Rarely it may be considered as a normal variant when an extensive physical and laboratory evaluation fails to reveal bladder instability.
Voiding cystourethrography (VCUG)
VCUG demonstrates dilatation of posterior urethra just distal to the internal sphincter. It may sometimes be only demonstrable during bladder filling wherein unstable bladder contractions lead to filling of urethra while leakage is prevented by voluntary contraction of distal urethral sphincter. The dilatation may persist or disappear during voiding.
It is important to recognise additional findings (as listed below) to facilitate diagnosis and differentiate between functional disorders like urge syndrome or detrusor-external sphincteric dyssynergia:
- bladder capacity
- bladder wall trabeculations
- sacculations and diverticulum
- vesicoureteric reflux
- post-void residue
Treatment and prognosis
Treatment includes management of behavioural disorder with voiding retraining and biofeedback training. Frequent and relaxed voiding is encouraged as a behavioural modification.
- 1. Saxton HM, Borzyskowski M, Robinson LB. Nonobstructive posterior urethral widening (spinning top urethra) in boys with bladder instability. Radiology. 1992;182 (1): 81-5. doi:10.1148/radiology.182.1.1727315 - Pubmed citation
- 2. Kutlu O, Koksal IT, Guntekin E et-al. Role of spinning top urethra in dysfunctional voiding. Scand. J. Urol. Nephrol. 2010;44 (1): 32-7. doi:10.3109/00365590903445223 - Pubmed citation
- 3. Saxton HM, Borzyskowski M, Mundy AR et-al. Spinning top urethra: not a normal variant. Radiology. 1988;168 (1): 147-50. doi:10.1148/radiology.168.1.3380951 - Pubmed citation
- 4. Pollack HM, McClennan BL, Dyer RB et-al. Clinical urography. Saunders. ISBN:0721669352. Read it at Google Books - Find it at Amazon