Bladder outlet obstruction and damage, and defect of the bladder wall are the two main medical causes of a distended bladder, according to Health Hype. In cases of incontinence, a distended bladder may result from a conscious decision to avoid urinating, as the micturition reflex is also under voluntary control. A distended bladder occurs when the bladder retains excess urine and stretches beyond its normal limits without emptying.
When the bladder cannot receive any more urine from the kidneys due to distension, a back flow is likely to result, writes Health Hype. This can lead to more serious complications, such as kidney failure, although obstructions higher in the urinary tract usually do not cause distension. Chronic cases of urinary retention are less serious than acute cases, as they involve the passing of some urine, however infrequent, difficult and painful.
Causes of bladder outlet obstruction in men and women include bladder stones, tumors, blood clots, fecal impaction and urethral strictures, states Health Hype. Urethral stricture, or urethral narrowing, is more common in men than in women. Neurogenic bladder can also cause outlet obstruction through affecting the detrusor muscle of the bladder wall and hindering relaxation of the urethral sphincter. Central and peripheral nervous system conditions, such as Parkinson's disease, multiple sclerosis, stoke and spinal cord injury, are causes of neurogenic bladder.