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What is the definition of incontinence?

Urinary incontinence is defined as the involuntary loss of urine that can be demonstrated objectively. It is a very common and underdiagnosed condition.


How common is urinary incontinence?

UI affects 15-30% of the general population.
It is more common in females (M:F = 1:3) and in the elderly.
Although UI rarely causes death, it is a considerable cause of morbidity (perianal irritation and sepsis, frequency and nocturia, social isolation and embarrassment).


How is UI classified?

UI is broadly classified into urethral incontinence (abnormality intrinsic to the urinary tract) and non urethral incontinence (abnormality originating outside the tract).

Urethral incontinence:
- urethral abnormalities: obesity, multiparity, difficult delivery, post-prostatectomy
- bladder abnormalities: neuropathic or non neuropathic detrusor abnormalities, infection, interstitial cystitis, bladder stones and tumours
- Non-urinary abnormalities: impaired mobility or mental function

Non urethral incontinence:
- Urinary fistula: vesicovaginal
- Ureteral ectopia: ureter drains into urethra (usually a duplex ureter)


What are the different types of urinary incontinence?

1) Stress incontinence (urethral) - pelvic floor injury
2) Urge incontinence (urethral) - detrusor instability
3) Neuropathic incontinence (urethral) - head injury, spinal injurym peripheral nerve injury
4) Anatomical (non urethral) - vesicovaginal fistula


What is stress incontinence?

Urine leaks when intra abdominal pressure exceeds urethral pressure (e.g. coughing, laughing or straining). Urethral incompetence often develops as a result of impaired urethral support due to pelvic floor muscle weakness.

Clinically, patients present with incontinence during laughing, sneezing or coughing etc. These symptoms are quite specific for stress incontinence. Volume infusion graphs show a sudden loss of bladder pressure during episodes indicating a leak.


What are the features of urge incontinence?

Urge incontinence happens because of uninhibited bladder contraction from detrusor hyperactivity. This causes a rise in intravesicular pressure and urine leakage. This may be caused by loss of cortical control (e.g. a stroke) or bladder inflammation from a stone, infection or neoplasm. Patients present with LUTS.

Volume infusion graphs show cyclical changes in pressure due to detrusor contractions and early voiding as patients have urgency to void.


What is mixed incontinence?

This is a combination of stress and urge incontinence.


When does nocturnal enuresis (bed wetting) become abnormal?

This occurs in 10% of 5 year olds and 5% of 10 year olds. If it occurs in an older child it can indicate bladder instability.


What is overflow incontinence?

This occurs in a neuropathic bladder. Damage to the efferent fibres of the sacral reflex causes bladder atonia. The bladder fills with urine and becomes grossly distended with constant dribbling of urine. It may result from bladder outflow obstruction (e.g. BPH) spinal cord injury or congenital defect (e.g. spina bifida) or neuropathy (e.g. diabetes)


What investigations are required when assessing a patient with incontinence?

- Voiding diary: useful to establish baseline
- Urine culture: exclude infection
- IVU: to assess upper tracts and obstruction or fistula
- Urodynamics: essential to determine the type of incontinence accurately
- Cystoscopy: if bladder stone or neoplasm suspected
- Vaginal speculum: if fistula suspected
- MRI: visualise pelvic floor defects


How do fistulas causing incontinence present?

Fistulas tend to present with continuous dribbling. On volume infusion graphs they have a relatively normal curve with some dripping leaks.


What investigations are important in urge incontinence?

Cystometry is the diagnostic tool that allows the assessment of inappropriate detrusor contractions. However, first line treatments are often given without this invasive test.


Outline the management of urge incontinence

Treatment of the condition should always involve resolving any causative pathology - e.g. UTI or a bladder stone. Conservative measures such as: good fluid intake of non caffeinated drinks; planning and timing of voiding; and avoiding letting the bladder get overfilled decrease the incontinence episodes.

Medical management follows unsuccessful conservative treatment. First line are anticholinergic drugs. These drugs work by blocking receptors on the detrussor muscle that respond to acetylcholine from the muscarinic nerves to the bladder and which are responsible for contraction.

Other treatments include:
- sacral nerve stimulation
- surgery


What type of incontinence is BOTOX used to treat? What are the complications of BOTOX treatment?

BOTOX or botulinum toxin is used to treat urge incontinence. It works in a similar way to antimuscarinic/ anticholinergic drugs. But rather than blocking the cholinergic receptors, it prevents the release of ACh from presynpatic nerve endings.

Treatment is performed via a flexible cystoscope and a special needle is used for the injection to ensure the right depth of penetration. 200-300 units of toxin are injected in 1ml volumes.

Complications include:
- 25% risk of self catheterisation following procedure
- blistering of the urothelium
- effects of the toxin last 6-9 months so the procedure needs to be repeated


What role does sacral nerve stimulation play in managing urge incontinence?

Sacral nerve stimulation is usually reserved for drug refractory urge incontinence. It is based on modulating the S2-S4 nerves which supply the parasympathetic input to the bladder and cause contraction.


What type of surgery is used to treat urge incontinence?

Surgery is often the last resort for patients who have refractory urge incontinence. A clam cytoplasty involves dividing the bladder in half "like a clam" and placing a piece of intestine into the opening. This increases the capacity of the bladder and possibly divides the abdominal nerves. The intestinal piece is a low pressure segment that can act like a diverticulum during contraction to prevent leakage.

This type of surgery is not without its complications, including: stone formation, infection, increased risk of malignant change, and metabolic disturbances. Because of this, patients require routine cystoscopy.


How should stress incontinence in women be managed?

Stress incontinence is much more common in women cf. men. NICE strongly recommend conservative measures in the first instance. Physiotherapy with pelvic floor (Kegel) exercises for 3 months can improve the strength of the pelvic diaphragm. Other conservative measures include stopping smoking, weight loss, and avoiding constipation.

Colposuspension and autologous pubovaginal slings are tried and tested operations. The principal being the placement of synthetic tape behind the posterior wall of the urethra to form a supporting hammock. There are different types of these including Burch and Stamey.

Injection of bladder neck bulging agents have a poorer long term results compared to sling procedures.


How should stress incontinence in men be managed?

Stress incontinence is much less common in men cf. women. It is commonly found with a history of trauma or surgery. Treatment of stress incontinence in men is based on increasing the resistance to outflow. The sphincter can be augmented by injecting a bulking agent, but this treatment has been shown to have a variable effect and is not a permanent solution.

Inserting an artifical sphincter in men does have good results. It is inserted around the bulbar urethra.


What is the management of overflow incontinence?

Avoid medicines that can cause detrusor hypoactivity: anticholinergics, calcium channel blockers.

If an obstruction is present then it is important to treat the underlying obstruction e.g. TURP in BPH.

If there is no obstruction, then a short period of catheter drainage is recommended. This is to allow the detrusor muscle time to recover from over stretching. This is followed by a short course of detrusor muscle stimulants such as bethanechol.