Cobra head appearance on excretory urography is suggestive of: March 2010

Ans. D: UreteroceleThe term ureterocele denotes a cystic ballooning of the distal end of the ureter. This type of ureterocele is also termed ohotopic, since it arises from a ureter with a normal inseion into the trigone.An intravesical ureterocele results from the prolapse of the mucosa of the terminal segment of the ureter through the ureterovesical orifice into the bladder.This prolapsed ureteral mucosa carries with it a poion of the continuous sheet of the bladder mucosa around the orifice. The prolapsed segment thus has a wall that consists of a thin layer of muscle and collagen interposed between the bladder uroepithelium and the ureter uroepithelium.Since the terminal ureteral orifice is usually narrowed and paially obstructed, and since there is no muscle suppo for the double mucosal walls of the prolapsed segment, it dilates. This dilated segment fills with urine and protrudes into the bladder.On excretory urography, cobra head sign is classically seen with an intravesical ureterocele.