Causes of urinary incontinence
Urinary incontinence affects about 5% of the population, with 8% of females and 3% of males affected respectively. It's more common in old age and in debilitated patients.
The causes differ from person to person, and for men and women respectively:
Stress urinary incontinence in females
• Hypermobility of the bladder neck and urethra related to the effects of childbirth
• Urethral-sphincter (valve-mechanism) dysfunction related to:
- childbirth injury
- previous surgery to the urethra or bladder neck
- atrophy of the genital tissues related to the menopause
Stress urinary incontinence in males
Urethral-sphincter (valve-mechanism) injury due to:
• transurethral resection of the prostate gland (1% risk)
• radical prostatectomy (approximately 5% risk)
• pelvic fracture
Urge incontinence (males and females)
• Detrusor (bladder muscle) instability due to:
- old age
- unknown cause (idiopathic)
- bladder stones
- bladder tumours
• Small capacity bladder due to:
- interstitial cystitis
- tuberculosis of the bladder
- schistosomiasis (bilharzia) of the bladder
- neuropathic bladder
• Obstruction of the bladder outlet (rare in females)
- benign prostatic enlargement (hyperplasia)
- prostate cancer (carcinoma)
- urethral strictures (narrowing)
• Poor bladder contraction due to damage to its nerve supply by:
- diabetes mellitus
- pelvic surgery
- low spinal cord injury
- multiple sclerosis
Total incontinence is usually due to an abnormal communication between the urinary tract and the outside:
• vesicovaginal fistula (a communication between the bladder and the vagina)
• ureterovaginal fistula (between the ureter and the vagina)
• ectopic ureter (a ureter opening in an abnormal position, e.g. vagina)
Causes of faecal incontinence
Normal bowel control relies on several factors such as the proper functioning of the pelvic muscles, the nervous system (spinal cord and brain), lower section of the large intestine (the rectum) and muscles surrounding the anus (sphincter muscles). If any of these areas are injured, it can cause bowel or faecal incontinence.
Here are seven of the most common causes of bowel incontinence:
1. Muscle damage
If there's injury to the muscles at the end of the rectum (anal sphincter), it may be more difficult to hold stool back effectively. Sphincter muscles can be damaged by constipation, haemorrhoids (piles) and childbirth, especially if labour involves an episiotomy or forceps delivery.
2. Nerve damage
If the nerves that control sphincter movement are damaged, the sphincter muscles will not close properly. When this happens, you'll not feel the urge to go to the bathroom. Some causes of nerve damage include childbirth trauma, frequent constipation, spinal cord injury, stroke and illnesses such as multiple sclerosis and diabetes.
Loose or watery stools associated with diarrhoea can cause or worsen faecal incontinence. Having loose stools can cause such a sudden urge to have a bowel movement that you're unable to get to the bathroom in time.
Chronic constipation may cause nerve damage and also lead to an accumulation of dry, solid stool in the rectum (impacted stool) that's too bulky for normal passage. This may cause the intestinal and rectal muscles to stretch and eventually weaken, allowing watery stool located higher in the digestive tract to move around the impacted stool and leak out.
Because certain illnesses such as ulcerative colitis, irritable bowel syndrome (IBS) and Crohn’s disease can also cause chronic or recurring diarrhoea, it’s really important to consult your doctor if you have FI.
External haemorrhoids (enlarged veins in the anus or rectum) can obstruct the sphincter so it's unable to close completely, therefore allowing an involuntary leakage of mucus and loose stool.
Several medications can also cause or worsen FI. These include broad-spectrum antibiotics, beta blockers, laxatives and antidepressants (especially tricyclics and SSRIs – selective serotonin reuptake inhibitors).
7. Pelvic-floor dysfunction
During childbirth, women can sustain injuries to nerves and muscles in the pelvis, but symptoms of pelvic floor dysfunction may only occur years or even decades later. These injuries include weakened pelvic muscles used during bowel movements, rectocele (when the rectum protrudes through the vagina because the thin muscles between the two become weak) and rectal prolapse (when the rectum drops down into the anus).
What is incontinence?
Image: Drawing to show the pelvic floor muscles and their support of the bladder from Shutterstock