Urinary incontinence Overview:
Definition:
Is the complaint of involuntary leakage of urine.
It results from failure to store urine during the filing phase of the bladder due to the following
1- Detrusor dysfunction
2- Urethral sphincter abnormalities
3- Anatomical abnormalities
It is usually urethral however it could be extra-urethral (ectopic ureter, vesico-vaginal fistula)
Prevalence:
It affects 3.5 million people in the UK.
It is twice as common in females compared to males.
Up to 20% of females above the age of 65 suffer from urinary incontinence and 10% of males at the same age.
Classification
1- Stress urinary incontinence (SUI)
Involuntary leakage of urine on effort, exertion, sneezing, or coughing.
It is due to the following:
a- Hypermobility of the bladder base (Urethral hypermobility)
b- Pelvic floor deficiency
c- Intrinsic urethral sphincter deficiency (ISD)
(These are not mutually exclusive)
It is categorized by Blaivas into
a- Type 0: no clinical signs of incontinence
b- Type 1: leakage during stress with less than 2 cm descent of the bladder base below the upper border of the symphsis pubis
c- Type 2: leakage on stress with more than 2 cm descent of the bladder during stress (2a) or even without stress i.e. permanently (2b)
d- Type 3: bladder neck and proximal urethra are open at rest regardless of descent, this is also known as (ISD)
2- Urge urinary incontinence (UUI)
Involuntary urinary leakage immediately preceded by urgency.
It is due to an overactive detrusor muscle.
3- Mixed urinary incontinence (MUI)
Combination of both SUI and UUI
4- Overflow incontinence
It happens in men with chronic urinary retention and degree of detrusor failure, the bladder is abnormally distended with large residual volumes. 30% develop renal failure.
5- Nocturnal enuriesis:
Loss of urine during sleep.
can be further classified into
primary types (never dry for longer than 6 mo period)
secondary (re bed wetting after being dry for at least 6-12 months)
in adult it could be overflow incontinence.
6- post micturition dribble:
In men due to pooling of urine in the bulbous urethra after voiding.
7- continuous incontinence
8- insensible incontinence
9- coital incontinence
Risk factors for UI
1- Female
2- Caucasian more than afro-carribeans
3- Neurological disorders (SCI, Stroke, MS, Parkinsons)
4- Anatomical disorders (vvf, ectopic ureters, urethral diverticulum)
5- Childbirth and pregnancy
6- Pelvic surgery (RPhttps://www.youtube.com/watch?v=SrFIbzqBPRc, TAH, TURP)
7- Rx
8- Diabetes
Promoting factors
1- Smoking (coughing increases pressure)
2- Obesity
3- UTI
4- Increase fluid intake
5- Medications (alpha blockers)
6- Aging, poor nutrition, cognitive deficits, poor mobility
7- Oestrogen deficiency
Pathophysiology
1- Bladder abnormalities
a- Detrusor overactivity:
involuntary bladder contractions during the filling phase this could be either
many hypothesis exist for DO:
- Myogenic: partial denervation of the detrusor
- Neurogenic: disruption of primary neural control in muscle cells
- Integrative hypothesis: abnormal or exaggerated peripheral autonomic activity within the peripheral myovesical plexus (intramural ganglia and interstitial cells) http://www.ncbi.nlm.nih.gov/pubmed/11502339
b- Low bladder compliance:
decreased volume-to-pressure relationship due to
alterations in elastic properties of the bladder wall, possible causes
2- Urethral and sphincter abnormalities
a- Urethral hypermobility:
A rotational descent of the bladder neck and proximal urethra during increases in intra-abdominal pressure and leakage of urine if the urethra opens concomitantly.It’s due to weakness of pelvic floor support.
b- Intrinsic sphincter deficiency (ISD):
An intrinsic malfunction of the sphincter, regardless of its anatomical position. (Type III SUI) (bladder neck and proximal urethra are open at rest regardless of descent)
Causes include:
- Inadequate urethral compression (SAMRA, urethral surgery, ageing, menopause, radical pelvic surgery, anterior spinal artery syndrome)
- Deficient urethral support (4 Ps, Pelvic floor weakness, parity, pelvic surgery, post menopause)
- Damage to the urethral sphincter in males (RP, TURP, Rx) https://www.youtube.com/watch?v=SrFIbzqBPRc
I conclude that pelvic floor weakness can cause both ISD and urethral hypermobility.
Theories for the pathogenesis of SUI include;
- Integral theory: laxity of anterior vaginal wall and pubourethral ligaments, causing bladder neck hypermobility.
- Hammock hypothesis: failure of urethral support by the endopelvic fascia and vaginal wall.
