cobb 's collar or moormann 's ring is a largely underestimated cause of male bulbar urethral strictures .
it can potentially lead to acute urinary retention , upper urinary tract dilatations , enuresis , infection , poor streaming , and hematuria .
embryologically , this focal bulbar urethral stricture develops due to failure of canalization of the cloacal membrane during fetal development . in cobb 's collar ,
the site of obstruction is more distal than that seen with posterior urethral valves ( puv ) .
a prompt diagnosis with minimally invasive treatment may avoid upper and lower tract deterioration in these patients .
we present two cases of congenital bulbar urethral obstruction ( cobb 's collar ) occurring in brothers .
the anatomy , embryology , and clinical features are discussed in order to turn the spotlight on to this rare disease .
a 30-year - old man presented with a long history of a worsening urinary stream and a sense of incomplete voiding and straining at micturition .
there was no history of traumatic injury , instrumentation of the urethra , or sexually transmitted disease .
abdominal and genitourinary examination revealed an enlarged and distended urinary bladder with normal - looking external genitalia .
renal function tests and urine routine examination were within normal limits , and urine culture showed no growth .
usg of the abdomen revealed bilateral mild hydronephrosis [ figure 1a ] , presence of hydroureters , a dilated prostatic urethra , and a thick - walled over - distended bladder .
pre - void ( 1972 ml ) , first ( 957 ml ) and second post - void ( 790 ml ) residual volumes were significantly raised [ figure 1b ] .
urodynamic study could not be performed as catheterization failed due to the tightness of the urethral stricture .
subsequent retrograde urethrogram ( rgu ) showed a 3-cm stricture in the bulbar urethra [ figure 2a ] .
micturating cystourethrogram ( mcu ) using the suprapubic route showed a narrowing in the proximal bulbar urethra , without reflux into the collecting system [ figure 2b ] .
suprapubic catheterization ( spc ) with visual internal urethrotomy ( viu ) was performed and the patient was discharged .
later , he was readmitted for a voiding trial and teflon dilatation . in view of the persistent urinary problems ,
the postoperative course was uneventful , and the patient voids without complaints at 6 months follow - up . ( a ) bilateral mild hydronephrosis ( b ) significant post - void urine residue ( case 1 ) ( a ) retrograde urethrogram demonstrating a narrowing in the proximal bulbar urethra , ( b ) micturating cystourethrogram ( mcu ) showed a narrowing in the proximal bulbar urethra ( white ring ) ( case 1 ) the first case 's 25-year - old younger brother also complained of poor urinary stream and straining at micturition .
usg showed mild hydronephrotic changes , hydroureters , and a thickened bladder wall , with significant post - voiding residue .
rgu was performed which showed a short segment stricture in the bulbar urethra [ figure 3 ] .
the patient is asymptomatic at 6 months follow - up , with normal serial usg evaluations .
a 30-year - old man presented with a long history of a worsening urinary stream and a sense of incomplete voiding and straining at micturition .
there was no history of traumatic injury , instrumentation of the urethra , or sexually transmitted disease .
abdominal and genitourinary examination revealed an enlarged and distended urinary bladder with normal - looking external genitalia .
renal function tests and urine routine examination were within normal limits , and urine culture showed no growth .
usg of the abdomen revealed bilateral mild hydronephrosis [ figure 1a ] , presence of hydroureters , a dilated prostatic urethra , and a thick - walled over - distended bladder .
pre - void ( 1972 ml ) , first ( 957 ml ) and second post - void ( 790 ml ) residual volumes were significantly raised [ figure 1b ] .
urodynamic study could not be performed as catheterization failed due to the tightness of the urethral stricture .
subsequent retrograde urethrogram ( rgu ) showed a 3-cm stricture in the bulbar urethra [ figure 2a ] .
micturating cystourethrogram ( mcu ) using the suprapubic route showed a narrowing in the proximal bulbar urethra , without reflux into the collecting system [ figure 2b ] .
suprapubic catheterization ( spc ) with visual internal urethrotomy ( viu ) was performed and the patient was discharged .
later , he was readmitted for a voiding trial and teflon dilatation . in view of the persistent urinary problems ,
the postoperative course was uneventful , and the patient voids without complaints at 6 months follow - up . ( a ) bilateral mild hydronephrosis ( b ) significant post - void urine residue ( case 1 ) ( a ) retrograde urethrogram demonstrating a narrowing in the proximal bulbar urethra , ( b ) micturating cystourethrogram ( mcu ) showed a narrowing in the proximal bulbar urethra ( white ring ) ( case 1 )
the first case 's 25-year - old younger brother also complained of poor urinary stream and straining at micturition .
usg showed mild hydronephrotic changes , hydroureters , and a thickened bladder wall , with significant post - voiding residue .
rgu was performed which showed a short segment stricture in the bulbar urethra [ figure 3 ] .
the patient is asymptomatic at 6 months follow - up , with normal serial usg evaluations .
the proximal prostatic and membranous part of the male urethra is formed by endodermal tissues and the penile part is formed from the phallic portion of the urogenital sinus .
congenital idiopathic urethral stricture may result from incomplete rupture of the cloacal membrane at the junction of membranous and bulbar urethra which may correspond to submeatal stenosis in girls .
1968 ) were the first to draw attention to the entity of congenital stricture of the bulbar urethra .
they analyzed 52 cases of proximal bulbar urethral obstruction in male patients for a 3-year period .
twenty - six out of 52 patients were boys under 16 years of age ; of these 26 boys , 16 had a trabeculated bladder , 15 showed a dilated prostatic fossa , whereas 6 had a secondary hydroureter , and the most frequently referred symptoms were enuresis , urinary tract infection , hematuria , and failure to thrive .
all these forms of obstruction are located just below the external sphincter [ figure 4 ] .
it can appear either as a ridge of tissue ( cobb 's collar i ) or as a definite stricture in the area described ( cobb 's collar ii ) or even as a very tight pinhole opening ( cobb 's collar iii ) .
p , prostate ; s , external sphincter ; c , cobb 's collar such strictures of the bulbar urethra had been underestimated for many years until the first half of the 1990s when dewan et al . and later nonomura et al . redefined and classified the bulbar urethral narrowing by reviewing video - recorded cystoscopies as well as radiological pictures in the patients .
both studies showed that the majority of patients were below 1 year of age with a large number showing vesicoureteral reflux ( vur ) , with no history of urethral trauma , catheterization , or instrumentation .
vur in association with clinical findings and endoscopic findings of vestigial remnants at the level of bulbar urethra indicates that this narrowing has a congenital onset .
presentation at a later age , as occurred in our cases , may represent delayed presentation of a congenital stricture .
their response to treatment is clearly different from that of the under 1 year olds , since majority require buccal mucosal onlay urethroplasty or scrotal or penile island flap urethroplasty .
the more common causes of congenital urethral stricture are different types of posterior urethral obstruction , which was originally described as puv ( three types ) by young et al . , but these obstructions were found to be diaphragmatic obstruction as suggested by parkkulainen on endoscopic studies .
congenital attachment of the verumontanum to the anterior wall of the posterior urethra is the embryologic forerunner to the congenital obstruction of the posterior urethra .
congenital obstructing posterior urethral membrane ( copum ) , first described by dewan et al .
more distal bulbar urethral abnormality without folds running up to the verumontanum is likely to be a remnant of urogenital diaphragm , commonly known as cobb 's collar .
, in their series of 12 pediatric patients with bulbar or posterior urethral stenosis , identified a sort of bimodal distribution of age at presentation , with 50% of patients presenting during the first year of life , whereas 5 of the remaining 6 patients presented after the age of 11 . this late presentation may represent a delayed presentation of a congenital stricture , or may be due to a forgotten urethral trauma or asymptomatic inflammation .
clinical presentation may be variable and , often , may be related to the use of blind urethral catheterization in these patients .
chronic urinary retention and bilateral hydronephrosis may be a presenting feature in some patients , as in our case .
late presentation of cobb 's collar ( caused by a persistence of urogenital membrane ) can be differentiated from acquired stricture by the absence of the characteristic folds between copum anomalies and verumontanum .
pediatric urologists continue to debate whether the cobb 's collar or moormann 's ring represents a true urethral stricture or not . some consider cobb 's collar to be a benign physiological narrowing of the bulbar urethra , easily passable with a cystoscope , although cobb describes a series of bulbar strictures in a pediatric population in his original paper .
so , although rare , cobb 's collar has to be considered in the differential diagnosis of progressive urinary flow obstruction and enuresis , especially in pediatric and adolescent patients where acquired traumatic , iatrogenic , or inflammatory strictures are more common .
radiologically indistinguishable dysfunctional voiding due to involuntary contraction of urethral sphincter or pelvic floor muscles and hinman syndrome ( functional non - neurogenic bladder ) are also important differential diagnoses to be considered .
contrast - enhanced conventional radiological studies can identify this anomaly and also be helpful in postoperative follow - up of this entity which can be easily treatable by minimally invasive endoscopic corrective surgery .
familial occurrence of cobb 's collar is exceedingly rare and only few cases are reported in the literature , indicating that this entity may have a familial basis .
screening for family members is an important part of managing these patients . in the absence of traditional risk factors
if the biopsy of the stricture and histological examination shows a normal urethral mucosa and the absence of any inflammation or fibrosis , then cobb 's collar becomes the likely diagnosis .
from the limited data available and from the cases reported here , it is clear that urethral strictures often present with an unknown etiology .
although extremely uncommon , in cases of adolescent or pediatric patients presenting with symptoms of progressive urinary obstruction and enuresis with or without urinary tract infection and/or hematuria , a bulbar urethral obstruction such as cobb 's collar should be considered .
 most urethral strictures arise from iatrogenic , traumatic , or inflammatory causes . 
 we report the familial occurrence of a congenital bulbar urethral stricture in two brothers . 
 retrograde and voiding cystourethrography was performed . 
 a cobb 's collar was diagnosed after radiological and endoscopic evaluation in both cases and was successfully managed with urethroplasty . 
 cobb 's collar is a rarely recognized cause of a membranous stricture of bulbar urethra that can lead to several urinary problems . in cases of adolescent and young adults presenting with symptoms of progressive urinary obstruction and enuresis with or without urinary tract infection , 
 cobb 's collar can be seen as a minor constriction in the bulbar urethra , but is not frequently symptomatic , and the familial occurrence of such a stricture is even rarer . 
Introduction
Case Reports
Case 1
Case 2
Discussion
Conclusion