[Cobb's collar … seek and you shall find!]

PURPOSE: Cobb's collar, also known as Moormann's ring, is a rare membranous stricture of the bulbar urethra. In contrast to the posterior urethral valve (PUV), Cobb's collar is not connected to the verumontanum. A simultaneous occurrence of PUV and Cobb's collar is even rarer. To the best of our knowledge, we report the third case in the literature of a child with coexistence of PUV and Cobb's collar.

CASE PRESENTATION: We present the case of a 3-year-old boy with a history of recurrent episodes of bladder outlet obstruction with residual urine volumes of up to 800 ml. An outward cystoscopy only revealed a bladder neck with a spastic appearance. A neuropediatric visit was unremarkable; magnetic resonance imaging (MRI) of the brain and spine was negative. After the positioning of a suprapubic catheter, cystoscopy was repeated, and a membranous stricture distal to the external sphincter - also known as Cobb's collar - was diagnosed and incised. After the procedure, the patient was able to urinate with residual volumes ranging from 40-50 ml. However, two weeks later, residual volumes increased again, and a second cystoscopy was performed. In addition to the open Cobb's collar, a PUV was detected, and both were incised with a cold hooked knife.

CONCLUSIONS: The diagnosis is difficult to make unless the urologist is aware of and actively looks for these rare congenital anomalies of the urethra, which present with variable clinical manifestations and degrees of obstruction.