Overflow incontinence

Definition

• Involuntary leakage of urine from an overdistended bladder due to reduced detrusor contractility or bladder outlet obstruction.
• It typically presents as dribbling from an overly full bladder; volumes are usually small, but leakage may be constant and result in large total losses.

Occurrence & epidemiology

Epidemiology

• Detrusor underactivity causes urinary retention and overflow incontinence in approximately 5% of patients with incontinence.
• Urinary retention is more common in men than in women; in women, detrusor underactivity is usually idiopathic.

Aetiopathogenesis

Aetiology and pathogenesis

• Detrusor underactivity results from injury to the spinal cord or nerve roots, for example from disc compression or tumour, or from peripheral or autonomic neuropathy, for example due to diabetes, alcoholism or vitamin B12 deficiency.
• In women, outlet obstruction may result from a prolapsed cystocele that kinks the urethra during straining, from a urethral stricture or from faecal impaction.
• Chronic obstruction leads to an overdistended bladder that loses its ability to contract and empties incompletely.
• Anticholinergic agents and opioids greatly decrease detrusor contractility and are common transient causes; calcium channel blockers can also cause retention with overflow incontinence.

Clinical features

• Symptoms include suprapubic pain, a feeling of incomplete emptying, a weak stream, urgency and incontinence.
• Some patients, particularly older ones, are asymptomatic despite urinary retention.
• If it persists, bladder decompensation, hydronephrosis, renal failure, vesicoureteral reflux, nephrolithiasis and urinary tract infections may result.

Diagnosis

• The diagnosis rests on a high post-void residual measured by bladder scanner, ultrasound or straight catheterisation; as normal maximum bladder capacity is about 500 mL, any larger volume is clearly abnormal.
• A post-void residual below 50 mL is normal and below 100 mL is usually acceptable in people over 65, whereas more than 100 mL may suggest detrusor underactivity or outlet obstruction.
• Urinalysis, urine culture and renal function tests are part of the baseline work-up.

Keep learning in the app

Further reading (selection)

1. StatPearls: Female Urinary Retention (NCBI Bookshelf)
2. StatPearls: Urge Incontinence (NCBI Bookshelf)
3. MSD Manual Professional: Urinary Incontinence in Adults

Cross-references