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Urinary incontinence

Involuntary loss (leakage) of urine.

Involuntary loss (leakage) of urine.


Classification

  • Stress incontinence: Urine leakage in association with coughing, sneezing or physical exertion
  • Urgency incontinence: Urine leakage associated with a sudden compelling desire to void that is difficult to defer
  • Mixed incontinence: Combination of symptoms of stress & urge incontinence
Overlap in lower urinary tract (LUT) conditions | Dr Anthony Pdw. (2020) Urinary troubles for more than the ageing – Drug Discovery World (DDW). Retrieved November 09, 2020, from https://www.ddw-online.com/urinary-troubles-for-more-than-the-ageing-944-200310/
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Other subtypes:

  • Overflow urinary incontinence: Involuntary leakage of urine from an overdistended bladder due to impaired detrusor contractility and/or bladder outlet obstruction
    • Neurologic diseases (can impair detrusor function): Spinal cord injuries, multiple sclerosis, and diabetes
    • Bladder outlet obstruction: External compression by abdominal/pelvic masses and pelvic organ prolapse, benign prostatic hyperplasia (in men)
  • Postural incontinence: Loss of urine with a change of body position (often when standing up or bending over)
  • Nocturnal enuresis: Leakage of urine during sleep
  • Continuous incontinence: Continuous urine leakage (eg. vesical fistulae)
  • Coital incontinence: Loss of urine during sexual intercourse
  • Functional incontinence: Incontinence in the setting of physical/cognitive impairment that limits mobility or the ability to process information about bladder fullness (eg. hip fracture or dementia)

Epidemiology

Urinary incontinence is considered a stigmatizing condition in most populations, which contributes to low rates of presentation for care and creates a high risk for respondent bias in observational studies.

Nearly 35% of women older than 40 years of age have urinary incontinence

Prevalence of stress, urgency and mixed incontinence stratified by age: The prevalence of stress incontinence peaks in the fifth decade and then declines, whereas the prevalence of both mixed and urgency incontinence continues to increase with age. Observational data are from France, Germany, Spain and the United Kingdom. Median prevalence data from a review of epidemiological studies from around the world have shown similar trends | Hunskaar S, Lose G, Sykes D, Voss S. The prevalence of urinary incontinence in women in four European countries. BJU Int. 2004;93:324–330.

Physiology

Anatomy and histology of the female bladder: The bladder lies immediately behind the pubic bones. When empty, the bladder has a pyramidal shape. As it fills and distends, the bladder balloons up above the pubic bones in an ovoid shape. The muscle of the bladder wall (the detrusor) consists of interdigitating fibres of smooth muscle, arranged in circular and longitudinal layers. These can stretch up to four times their resting length, so there is no increase in linear tension (or pressure) during normal bladder filling. The bladder and the ureters are both lined by a transitional epithelium, the urothelium. It contains flattened (‘umbrella’) cells and cuboidal cells, which also enable stretch as the bladder fills. The base of the bladder is a triagonal area, called the trigone. The ureters enter at the two superior corners of this triangle and the bladder neck lies at the inferior corner. The bladder neck is in continuity with the urethra, which, in women, is 2.5–4 cm long. The internal sphincter is formed of rings of smooth muscle at the bladder neck, whereas the external sphincter is formed by the muscles of the pelvic floor. Both sphincters help to close off the urethra to maintain continence. | Aoki, Y., Brown, H. W., Brubaker, L., Cornu, J. N., Daly, J. O., & Cartwright, R. (2017). Urinary incontinence in women. Nature reviews. Disease primers, 3, 17042. https://doi.org/10.1038/nrdp.2017.42

Neurological control:

  • Sympathetic nervous system: Predominates during the storage phase and maintains continence through the paravertebral ganglia, the hypogastric nerves and hypogastric plexus.
  • Parasympathetic system: Coordinates the voiding phase, through the sacral plexus and pelvic nerves (S2–S4). Afferent signals from the urothelium and bladder wall are transmitted through to the thalamus; the balance between storage and voiding is maintained by the central pontine micturition centre
  • Neurotransmitters responsible: Acetylcholine & noradrenaline
Neurological control of the urinary bladder: a) The sympathetic system predominates during the storage phase and maintains continence through the paravertebral ganglia and the hypogastric nerves and plexus. b) The parasympathetic system coordinates the voiding phase, through the sacral plexus and pelvic nerves (S2–S4). Afferent signals come from the urothelium and the bladder wall, through the pelvic nerves, and then go to the dorsal root ganglia and are projected to the periaqueductal grey, then to the posterior cingulate cortex (PCC). c) The main circuits for regulating desire to void include the insula and the lateral and medial prefrontal cortices, which feedback to the periaqueductal grey. The periaqueductal grey serves as a relay station for bladder information and activates the pontine micturition centre, which contracts the bladder and relaxes the urethral sphincter mechanism during voiding. d) The neurotransmitters responsible for the execution of these commands are acetylcholine and noradrenaline. | Aoki, Y., Brown, H. W., Brubaker, L., Cornu, J. N., Daly, J. O., & Cartwright, R. (2017). Urinary incontinence in women. Nature reviews. Disease primers, 3, 17042. https://doi.org/10.1038/nrdp.2017.42

Hammock hypothesis:

The endopelvic fascia (fibromuscular connective tissue of vagina) creates a ‘hammock’ against which the urethra is compressed during rest and activity. This compression, combined with ‘intrinsic’ urethral sphincter pressure and mucosal coaptation, effectively closes the urethral lumen and prevents the involuntary loss of urine even when the intravesical pressure increases.
Urethral support (in females): Posterior urethra lies on a supportive tissue layer composed of the anterior vaginal wall (part a) and the endopelvic fascia (part b). These structures are suspended from the arcus tendineus and in combination with a functional levator ani, create a ‘hammock’ that results in compression of the urethra with increased intra-abdominal pressure, preventing urinary leakage | DeLancey JOL. Structural support of the urethra as it relates to stress urinary incontinence: the hammock hypothesis. Am J Obstet Gynecol. 1994;170:1713–1723. An explanation of stress urinary incontinence pathology and the hammock hypothesis.
  • Voiding up to 7 times/day in waking hours is considered normal, with micturition volume of 250–300 ml/void

Pathophysiology

Stress urinary incontinence:

  • Urethral hypermobility: Resulting from loss of support of the bladder neck & urethra “hammock hypothesis” (such that they move during peaks of abdominal pressure)
    • Excess loading from obesity, chronic cough, constipation, parturition or menopause
  • Intrinsic sphincter deficiency: Weakness of urinary sphincter itself
    • Can result from trauma, repeated urogynaecological surgeries, neurological disease, ageing or diseases leading to systemic muscular atrophy

Urgency urinary incontinence:

  • Detrusor overactivity: Common after spinal injuries, with substantial spinal disease from multiple sclerosis or other lesions of the central nervous system
  • Poor detrusor compliance: After pelvic radiotherapy, or prolonged catheterization.
  • Bladder hypersensitivity

Diagnosis

Diagnostic work-up of women with urinary incontinence: Initial management of urinary incontinence includes a detailed history and physical examination to identify potential reversible causes of symptoms, followed by urinalysis with microscopy, voiding diary, assessment of post-void residual volume and cough stress test to assist with diagnosis and initial management. In cases of advanced pelvic organ prolapse, prior pelvic surgery, haematuria or urinary retention, patients may be referred to a urologist or urogynaecologist. | UTI, urinary tract infection. | Aoki, Y., Brown, H. W., Brubaker, L., Cornu, J. N., Daly, J. O., & Cartwright, R. (2017). Urinary incontinence in women. Nature Reviews. Disease Primers, 3, 17042. https://doi.org/10.1038/nrdp.2017.42

3 Incontinence Questions (3IQ):

Simple, quick, and noninvasive test with acceptable accuracy for classifying urge and stress incontinence
Brown, J. S., Bradley, C. S., Subak, L. L., Richter, H. E., Kraus, S. R., Brubaker, L., Lin, F., Vittinghoff, E., Grady, D., & Diagnostic Aspects of Incontinence Study (DAISy) Research Group (2006). The sensitivity and specificity of a simple test to distinguish between urge and stress urinary incontinence. Annals of internal medicine, 144(10), 715–723. https://doi.org/10.7326/0003-4819-144-10-200605160-00005

Cough stress test

Urethral leakage provoked by a series of forceful coughs in supine/standing position with a comfortably full (~300 ml) bladder volume

Valsalva manoeuvre: For pelvic organ prolapse

Forced attempted exhalation against a closed airway over ≥6 seconds in whichever position maximum protrusion is best demonstrated (supine, left lateral or standing).

Urinalysis

Recommended as a screening tool for UTIs and other associated conditions in the assessment of urinary incontinence
  • Revised McGreer criteria for diagnosing UTIs recommended

Post-void residual volume (PVR) assessment:

Determined by measuring the volume remaining in the bladder immediately after voiding as a measure of the completeness of bladder emptying
  • Via ultrasonography, with either a bladder scanner or formal renal tract imaging, or an in–out catheter.

Voiding diaries:

Three types of urinary diary can be used: a micturition chart to record the timing of each void, a frequency–volume diary to record the volume voided with the time and a bladder diary to record additional information on urinary incontinence episodes, pad usage, fluid intake, fluid type and sensation of urgency

Pad testing

Absorbent perineal pad worn for up to 24 hours while conducting a range of normal activities designed to replicate the usual provocations of urinary incontinence, such as walking and exercising

Urodynamic studies:

Series of investigations assessing lower urinary tract function that include uroflowmetry, voiding cystometry, filling cystometry, urethral function and provocative manoeuvres to demonstrate urinary incontinence
Multichannel urodynamic testing: Invasive (catheterized) pressure measurements during urodynamic studies include intravesical pressure (using a probe in the bladder) and abdominal pressure (using a probe in the rectum as shown or in the vagina (not shown)). In addition, electromyography (EMG) can be used to evaluate the activity of the muscles of the pelvic floor. During the test, the bladder is filled and then the patient is asked to void, with continuous pressure monitoring during filling and emptying. In women with urgency incontinence, findings can include uninhibited contraction of the detrusor muscle during filling (detrusor overactivity) or a gradual uncomfortable rise in pressure during filling (low compliance). A formal diagnosis of stress incontinence is made by observation of leakage with coughing or exertion in the absence of detrusor contraction. | Aoki, Y., Brown, H. W., Brubaker, L., Cornu, J. N., Daly, J. O., & Cartwright, R. (2017). Urinary incontinence in women. Nature Reviews. Disease Primers, 3, 17042. https://doi.org/10.1038/nrdp.2017.42

Management

Urge urinary incontinence (UUI)

  • Anticholinergic drugs: Oxybutynin, tolterodine
  • Surgery:
    • Intravesical Botox
    • Sacral nerve stimulation

Stress urinary incontinence (SUI):

  • Weight loss
  • Kegel (pelvic floor) exercises with or without biofeedback
  • Sling procedures
  • Transurethral collagen denaturation (Renessa procedure)
  • Transurethral bulking agents
Surgical treatment for urinary incontinence Surgical correction of urethral hypermobility, which results from loss of support of the bladder neck and proximal urethra such that they move during peaks of abdominal pressure, can involve the use of a synthetic mesh, suture or autologous tissue. A synthetic mesh is placed inside the vagina at the level of the mid-urethra and is passed either retropubically (part a) or via the transobturator approach (part b). Sutures are not used in either of these ‘tension-free’ procedures; the body tissues and fibrosis hold the mesh in place. Conversely, retropubic urethropexy (part c) involves the placement of permanent sutures in the anterior vaginal wall at the level of the bladder neck and proximal urethra. Finally, autologous fascial sling placement (part d) involves harvesting a strip of rectus fascia that is placed beneath the proximal urethra through a vaginal incision; the two ends of the sling are passed behind the pubic bone and are secured with permanent sutures either to each other or to the rectus fascia. | Fatton B, de Tayrac R, Costa P. Stress urinary incontinence and LUTS in women — effects on sexual function. Nat Rev Urol. 2014;11:565–578.

Overflow incontinence (OFI)

  • α-adrenergic blockers
  • 5-α-reductase inhibitors
  • Intermittent catheterization
  • Surgical options

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