Urinary incontinence

• Urinary incontinence (UI) is the involuntary leakage of urine. It affects around 15% of the general population, most common in the elderly, and is more common in females

  • Stress incontinence
  • Urge incontinence
  • Mixed incontinence
  • Overflow incontinence
  • Continuous incontinence
• Stress UI:

  • Urine leakage occurring when the intra-abdominal pressure exceeds the urethral pressure
  • Coughing, straining, laughing
  • The impaired urethral support is most often due to weakness of the pelvic floor muscle
  • Most commonly seen post-partum
  • Other risk factors: constipation (recurrent straining), obesity, post-menopausal or pelvic surgery
• Urge UI:

  • Describes an overactive bladder (detrusor hyperactivity) which leads to uninhibited bladder contraction
  • Rise in intravesical pressure and leakage of urine
  • Involuntary leakage accompanied, or immediately preceded by, urgency - sudden compelling desire to pass urine that is difficult to defer
  • Idiopathic in most women but may be associated with neurological conditions
  • Other risk factors - recurrent UTIs, bladder stones, diabetes
• Mixed UI is a combination of stress UI and urge UI
• Overflow UI:

  • Normally a complication of chronic urinary retention
  • Progressive stretching of the bladder wall leads to damage to the efferent fibres of the sacral reflex and loss of bladder sensation
  • As the bladder fills with urine it becomes grossly distended, but intravesicular pressure still builds, leading to a constant dribbling of urine
  • Most common cause is prostatic hyperplasia
  • Other causes - anticholinergic medications, fibroids, pelvic tumours and neurological conditions
  • More common in males - women with suspected overflow incontinence should be referred for urodynamic testing
• Continuous UI is the constant leakage of urine, meaning the patient is wet all the time. This is typically due to anatomical abnormality (such as ectopic ureter) or bladder fistulae (e.g. vesicovaginal fistula), however may also be due to severe overflow incontinence.
• Risk factors:

  • increased age
  • Postmenopausal status
  • Increased BMI
  • Previous pregnancies and vaginal deliveries
  • Pelvic organ prolapse
  • Pelvic floor surgery
  • Neurological conditions
  • Cognitive impairment and dementia
• Assess for modifiable lifestyle factors that contribute to symptoms:

  • Caffeine consumption
  • Alcohol consumption
  • Medications
  • BMI
• Assess the severity by asking about:

  • frequency of urination
  • Frequency of incontinence
  • Night time urination
  • Use of pads and changes of clothing
• Examination should assess the pelvic tone and examine for:

  • Pelvic organ prolapse
  • Atrophic vaginitis
  • Urethral diverticulum 
  • Pelvic masses

  During the examination, ask the patient to cough and watch for leakage from the urethra.
• The strength of the pelvic muscle contractions can be assessed during a bimanual examination by asking the woman to squeeze against the examining fingers. This can be graded using the modified Oxford grading system: 

  • 0: No contraction 
  • 1: Faint contraction
  • 2: Weak contraction
  • 3: Moderate contraction with some resistance
  • 4: Good contraction with resistance
  • 5: Strong contraction, a firm squeeze and drawing inwards 
• Investigation:

  • Bladder diary - tracking fluid intake and episodes of urination and incontinence over at least 3 days
  • Urine dipstick - infection, microscopic haematuria
  • HbA1c
  • U&Es if retention suspected
  • Post-void residual bladder volume
  • Urodynamic testing - investigate patients with urge incontinence not responding to medical treatment, urinary retention, or unclear diagnosis. Not always required where the diagnosis is possible based on history and exam
• Urodynamic tests:

  • Stop taking any anticholinergic and bladder related medications for 5 days prior
  • Thin catheter inserted into the bladder and another into the rectum
  • Bladder is filled with liquid and various outcome measures are taken:
  • Cystometry - detrusor muscle contraction and pressure
  • Uroflowmetry - flow rate
  • Leak point pressure - point at which the bladder pressure results in leakage
  • Post-void residual bladder volume
  • Video urodynamic testing - filling bladder with contrast and taking x-rays
• Management of stress incontinence:

  • Avoid caffeine, diuretics and overfilling of the bladder
  • Avoid excessive or restricted fluid intake
  • Weight loss
  • first line = Supervised pelvic floor exercises for at least 3 months before considering surgery (8 contracts at least 3 times a day)
  • Intravaginal oestrogen therapy for post-menopausal women (monitor for symptoms of endometrial cancer)
  • Surgery
  • Duloxetine is an SNRI antidepressant used second line where surgery is not preferred - enhances stimulation of urethral striated muscle
• Surgical options for stress incontinence:

  • Tension-free vaginal tape (TVT): mesh sling looped under the urethra and up behind the pubic symphysis to the abdominal wall. This supports the urethra.
  • Autologous sling procedures: works similar to TVT but a strip of fascia from the patient's abdominal wall is used
  • Colposuspension: stitches connecting the anterior vaginal wall and pubic symphysis, around the urethra, pulling the vaginal wall forward and adding support to the urethra
  • Intramural urethral bulking: injections around the urethra
• Where the stress incontinence is caused by a neurological disorder or other surgical methods have failed, specialist centres may offer an operation to create an artificial urinary sphincter. This involves a pump inserted into the labia that inflates and deflates a cuff around the urethra, allowing women to control their continence manually. 
• Anticholinergic medications need to be used carefully, as they have anticholinergic side effects. These include dry mouth, dry eyes, urinary retention, constipation and postural hypotension. Importantly they can also lead to a cognitive decline, memory problems and worsening of dementia, which can be very problematic in older, more frail patients. 
• Mirabegron is used as an alternative medical treatment for urge incontinence with less of an anticholinergic burden. However, it is worth noting that mirabegron is contraindicated in uncontrolled hypertension. Blood pressure needs to be monitored regularly during treatment. It works as a beta-3 agonist, stimulating the sympathetic nervous system, leading to raised blood pressure. This can lead to a hypertensive crisis and an increased risk of TIA and stroke.
• Invasive options for overactive bladder that has failed to respond to retraining and medical management include:

  • Botulinum toxin type A injection into the bladder wall - blocks release of Ach which relaxes detrusor muscle
  • Injections not permanent, need repeat treatment
  • Percutaneous sacral nerve stimulation involves implanting a device in the back that stimulates the sacral nerves - S3 neuromodulation
  • Augmentation cystoplasty involves using bowel tissue to enlarge the bladder
  • Urinary diversion involves redirecting urinary flow to a urostomy on the abdomen
• Conservative management of urge incontinence:

  • Review medications e.g. diuretics
  • Reduce caffeine/irritants (alcohol)
  • Reduce fluid intake before bed
  • 1.5-2L fluid a day
  • Weight loss
  • Avoid constipation
  • Offer bladder retraining for a minimum of 6 weeks - increase time between voids (retrains continence centres in brain)
• Medical management of urge incontinence:

  • If symptoms persist despite bladder retraining
  • First line = antimuscarinic (oxybutynin)
  • Anticholinergics block Ach release (parasympathetic nerves) and cause detrusor muscle relaxation
  • Will take at least 4 weeks to work
  • Common side effects = constipation, urine retention, cognitive decline, blurred vision
  • Second line = mirabegron (beta 3 adrenoreceptor agonist)
  • Agonist of sympathetic nervous system
  • Caution in hypertension or QT prolongation
• Stress incontinence risk factors:

  • Age
  • Parity - vaginal or forceps delivery
  • Antenatal and postpartum onset
  • Smoking
  • Obesity or other causes of chronic increases intrabdominal pressure
  • Hysterectomy
  • Menopause
  • Connective tissue disorders