Overflow Incontinence

Overflow incontinence happens when the bladder is unable to empty completely, leading to leakage (i.e. ‘overflow’) of urine when the bladder is full beyond its maximum capacity. Patients may or may not sense their full bladder and will involuntarily pass small amounts of urine frequently.

Causes

The commonest cause for overflow incontinence is obstruction to the bladder outlet. This can be caused by:

Enlarged prostate gland in men – the prostate gland sits at the outlet of the bladder; it enlarges with age and thus is the commonest cause for bladder outlet obstruction leading to overflow incontinence
Stones – Bladder or urethral stones
Tumours – tumours which grow around the bladder outlet or urethra
Scar tissue – Patients who had previous trauma, instrumentation or surgery may develop scar tissue which narrows the bladder outlet (strictures, stenosis)

Overflow incontinence may also be caused by weakness of the bladder wall muscles (detrusor muscles) leading to incomplete emptying of the bladder. This is usually due to damage to the nerves controlling the detrusor muscles or to the bladder muscles themselves. This can happen when there is:

Damage to the nerves supplying the bladder muscles from the brain or spinal cord
Congenital – Patients are born with spinal cord defects like spina bifida
Spinal cord disease, tumors or injury from trauma
Strokes
Damage to nerves supplying bladder muscles directly
Failure of the bladder muscles to work

Complications

Urinary tract infection : The inability to completely empty the bladder will lead to stasis of urine in the bladder. This predisposes the patient to infections that may involve the kidneys or become very chronic unless the bladder is also emptied during antibiotic treatment.
Deterioration of kidney function : Chronic retention of urine i.e. having a full bladder for a prolonged period results in the high pressures from the bladder being transmitted back up to the kidneys. This prolonged back pressure transmission damages the kidney tissue and can eventually lead to kidney failure
Bladder stones : Constant stasis of dirty urine can also lead to stone formation and its complications

Treatment

The immediate treatment would be to empty the full bladder using a catheter (a thin tube passed through the urethra into the bladder). This may either be an indwelling catheter (stays in place and is connected to a urine bag) or a single use, disposable catheter (where patients learn to catheterize themselves a few times a day to empty the bladder completely a.k.a. clean intermittent self catheterization – CISC).If the underlying cause is obstruction, surgery may be required e.g. resection of prostate, removal of stones/tumours and dilatation of strictures.

The long term aim management aim is to correct the underlying cause (if possible) and to prevent complications which may arise from long term indwelling catheters or long term CISC. These include recurrent infections, stone formation, renal deterioration and bladder cancer.

Indwelling catheter

Disposable catheters for CISC