Causes of Urinary Incontinence

Urinary incontinence is a symptom that can be caused by a variety of underlying medical conditions. A careful evaluation by your physician can determine the reason behind the incontinence.

Stress Incontinence

Stress incontinence is generally a consequence of weak or damaged muscles that prevent urination, for example the pelvic floor muscles and the urethral sphincter. When the abdominal muscles tighten (like when you’re sneezing or lifting something heavy), the pressure created overrides weak muscle control and forces urine to leak out of the body.

Urge Incontinence

In certain cases the detrusor muscles contract excessively, causing an urgent need to go to the toilet. This is known as having an “overactive bladder”. The cause of contraction of the detrusor muscle is not clear, but probable causes include:

  • too much alcohol or caffeine
  • poor fluid intake
  • constipation
  • urinary tract infections
  • bladder tumors
  • neurological conditions

Overflow Incontinence

Overflow incontinence, also referred to as chronic urinary retention, is generally a result of a blockage or obstruction to your bladder. Your bladder would fill up normally, but since it is obstructed, you are unable to drain it completely, even if you try.

As a result, pressure in the bladder increases as urine accumulates, leading to frequent leaks.

Bladder obstruction occurs as a result of:

  • an enlarged prostate gland in men
  • bladder stones
  • constipation

Overflow incontinence can also be a result of detrusor muscle malfunction, meaning your bladder is unable to drain completely when you urinate. Consequently, the bladder becomes stretched.

Detrusor muscles may not fully contract if:

  • there is damage to the nerves
  • you are taking some medications (example: diuretics, ACE inhibitors)

Functional Incontinence

Functional incontinence happens when your bladder is unable to hold any urine at all. It can make you pass a large amount of urine constantly, or pass urine every once in a while with frequent leaking.

Functional incontinence is caused by:

  • bladder defect from birth
  • spinal cord injury that interrupts nerve signals between the brain and bladder. See figure 1 below.
  • a bladder fistula – a small tunnel-like hole formed between the bladder and an adjacent area

Risk Factors

Certain factors increase the likelihood of urinary incontinence developing, such as:

  • pregnancy and vaginal birth
  • obesity
  • family history of incontinence
  • aging