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Urinary Incontinence: An Overview

Introduction

The International Continence Society Standardization Committee defines urinary incontinence as “a condition in which involuntary loss of urine is a social or hygienic problem and is objectively demonstrable.” 1Bates P, Bradley WF, Glen E, Griffiths D, Melchior H, Rowan D, et al. The standardization of terminology of lower urinary tract function. J Urol. 1979;121:551-554.   Indeed, the unwitting passage of urine is one of the most serious social disasters which can strike anyone. It would not be an exaggeration to say that urinary incontinence is a highly undiagnosed, under-reported, and often untreated medical condition with a tremendous impact on the quality of life for patients of all ages.2Herbruck LF. Urinary Incontinence in the Childbearing Woman. Urol Nurs. 2008;28(3):163-171.  

Physiology of continence and incontinence

Continence and micturition involve a balance between urethral closure and detrusor muscle activity. Normally, the pressure in the urethra is more than that in the bladder. As a result, urine stays inside the bladder. Since the proximal urethra and bladder are both within the pelvis, any increase in the intra-abdominal pressure (due to coughing, sneezing, etc.) is transmitted to both urethra and bladder equally so that the pressure differential remains unchanged, resulting in continence. Changes in both these pressure factors – i.e., a fall in urethral pressure and rise in bladder pressure – culminate in normal voiding.3Urinary incontinence. Available at http://en.wikipedia.org/wiki/Urinary_incontinence. Accessed on Nov 10, 2010  

Normal micturition occurs when contraction of the detrusor muscle induces an opening of the bladder neck, which is preceded by complete relaxation of the pelvic floor and external sphincter. Disturbance of this sequence may occur at any point and lead either to retention or incontinence of urine.4Shuttleworth KED. Incontinence. British Medical Journal 1970;4:727-729.  

Thus, urinary incontinence results from a disruption of micturition physiology, functional urinating ability, or both.5Walid MS, Heaton RL. Stepwise Multimodal Treatment of Mixed Urinary Incontinence with Voiding Problems in a Patient with Prolapse. Journal of Gynecologic Surgery 2009; 25 (3): 121-127.   The underlying pathology depends on the type of incontinence.

Causes of incontinence 3Urinary incontinence. Available at http://en.wikipedia.org/wiki/Urinary_incontinence. Accessed on Nov 10, 2010.  

  • Polyuria, which, in turn, is mostly due to uncontrolled diabetes mellitus, primary polydipsia, central diabetes insipidus and nephrogenic diabetes insipidus. Polyuria generally causes urinary urgency and frequency, and not necessarily incontinence.
  • Caffeine or cola beverages also stimulate the bladder.
  • Enlarged prostate is the most common cause of incontinence in men after the age of 40.
  • Prostate cancer may be associated with urinary incontinence.
  • Drugs or radiation used to treat prostate cancer can cause incontinence.
  • Brain disorders like multiple sclerosis, Parkinson’s disease, strokes and spinal cord injury can disturb the nerve function of the bladder.

Types of incontinence

Urge incontinence

Urge incontinence, also called overactive bladder (OAB) syndrome, is characterized by a sudden strong desire to pass urine that is difficult to control, leading to involuntary urine leakage. It usually entails urgency, frequency or nocturia. If it is due to a pure sensory abnormality in which there is urinary frequency and urgency without urine loss, it is termed ‘dry overactive bladder’. In elderly persons, frequent urinary loss occurs without the sensation of urge.

Urge incontinence occurs due to detrusor hyperactivity, leading to unrestrained bladder contraction.6Mills W, Grennland JE, McMurray G. Studies of the pathophysiology of idiopathic detrusor instability: the physiologic properties of detrusor smooth muscle and its pattern of instability. J Urol. 2000;163(2):646-51.  ,7Wein AJ, Rackley RR. Overactive bladder: a better understanding of pathophysiology, diagnosis and management. J Urol. 2006;175 (3 pt 2):s5-10.   This hyperactivity, in turn, can be caused by abnormalities of the CNS inhibitory pathway, such as stroke or cervical stenosis. Bladder inflammation due to infection, stones, or neoplasms can also cause this type of incontinence.

Type of incontinence Symptoms Causes
Urge urinary incontinence (overactive bladder in between overactivity) Involuntary leakage of urine immediately preceded or accompanied by urgency; sudden sensation of a need to urinate with inability to get to a toilet before involuntary leakage Overactive bladder; detrusor overactivity ± spontaneous contraction, bladder infections, nerve damage due to stroke, dementia, or multiple sclerosis
Stress urinary incontinence Involuntary leakage upon effort or exertion, or on sneezing or coughing; loss of urine upon increased abdominal pressure Urethral hypermobility due to weakened pelvic floor muscles, pregnancy, intrinsic sphincter deficiency, or aging
Mixed urinary incontinence Involuntary leakage associated with urgency as well as with exertion, effort, or increased abdominal pressure, causing symptoms of both conditions As above; usually the type causing the most bothersome symptoms should be treated first
Overflow incontinence Condition where the bladder is full but not able to empty properly. This causes leaks, dribbles, and hesitancy. More common in men. Urethral blockage hindering passage of urine from the bladder; weakened bladder contractions due to diabetes mellitus or neurologic disorder
Functional incontinence Condition where the urinary system is normal, but sufferers have mental or physical conditions that preclude adequate or appropriate urination Parkinson’s disease, Alzheimer’s disease, severe depression, severe arthritic conditions
Reflex incontinence Involuntary loss of bladder control without warning; the bladder empties due to reflex activity with no control of urination Neurological impairment, such as quadriplegia or spinal cord lesions

Stress incontinence

Stress incontinence is characterized by urine leakage associated with increased abdominal pressure due to laughing, sneezing, coughing, climbing stairs, or other physical stressors on the abdominal cavity and, hence, the bladder.8-108) Nazir T, Khan Z, Barber HR. Urinary incontinence. Clin Obstet Gynecol. 1996;39(4):906-11.
9) [Guideline] American College of Obstetricians and Gynecologists. Urinary incontinence in women. Obstet Gynecol. 2005;105(6):1533-1545.
10) [Guideline] Rogers RG. Clinical practice: urinary stress incontinence in women. N Engl J Med. 2008; 358:1029-1036.  

It usually occurs when urethral support gets impaired due to weakness of pelvic floor muscles, but an intrinsic sphincter deficiency secondary to pelvic surgeries can also cause it. Both these conditions impair urethral sphincter function, resulting in urine loss at lower than usual abdominal pressures.

Mixed incontinence8-118) Nazir T, Khan Z, Barber HR. Urinary incontinence. Clin Obstet Gynecol. 1996;39(4):906-11.
9) [Guideline] American College of Obstetricians and Gynecologists. Urinary incontinence in women. Obstet Gynecol. 2005;105(6):1533-1545.
10) [Guideline] Rogers RG. Clinical practice: urinary stress incontinence in women. N Engl J Med. 2008; 358:1029-1036.
11) Gibbs CF, Johnson TM 2nd, Ouslander JG. Office management of geriatric urinary incontinence. Am J Med. 2007;120(3):211-220.  

Mixed incontinence is a condition in which stress and urge incontinence are both present, and is characterized by involuntary loss of urine associated with urgency as well as exertion, coughing, sneezing, or any activity that increases intra-abdominal pressure. This is the most common type of incontinence in women.

It is generally attributed to detrusor overactivity and impaired urethral function, but the actual pathophysiology is still not clear.

Overflow incontinence8-118) Nazir T, Khan Z, Barber HR. Urinary incontinence. Clin Obstet Gynecol. 1996;39(4):906-11.
9) [Guideline] American College of Obstetricians and Gynecologists. Urinary incontinence in women. Obstet Gynecol. 2005;105(6):1533-1545.
10) [Guideline] Rogers RG. Clinical practice: urinary stress incontinence in women. N Engl J Med. 2008; 358:1029-1036.
11) Gibbs CF, Johnson TM 2nd, Ouslander JG. Office management of geriatric urinary incontinence. Am J Med. 2007;120(3):211-220.  

Overflow incontinence is characterized by continuous leakage of small amounts of urine, associated with weak urinary stream, dribbling, hesitancy, frequency, and nocturia. It is largely due to incomplete bladder emptying following impaired detrusor contractility or bladder outlet obstruction. Situations in which this can occur include physical obstruction, such as pelvic organ prolapse and enlarged prostate, and neurological abnormalities, such as spinal cord injuries. Bladder neuropathy due to diabetes mellitus is another common cause.

Functional incontinence

Patients with normal voiding systems but experiencing difficulty reaching the toilet because of physical or psychological impediments are said to suffer from functional incontinence. This condition is often secondary to reversible causes of urinary incontinence, and carries a good prognosis for cure if the cause is identified and treated.

Reflex incontinence

Reflex incontinence is characterized by loss of bladder control without warning, leading to emptying of the bladder. It is due to reflex activity, with no control of urination. This condition may be caused by neurological impairment, as happens in quadriplegia or spinal cord lesions.2Herbruck LF. Urinary Incontinence in the Childbearing Woman. Urol Nurs. 2008;28(3):163-171.  

Table 1 summarizes the various types of incontinence, their symptoms and causes.

Assessment and Management

An algorithm on the assessment and management of urinary incontinence in women is given in Fig. 1.

References

  1. Bates P, Bradley WF, Glen E, Griffiths D, Melchior H, Rowan D, et al. The standardization of terminology of lower urinary tract function. J Urol. 1979;121:551-554.
  2. Herbruck LF. Urinary Incontinence in the Childbearing Woman. Urol Nurs. 2008;28(3):163-171.
  3. Urinary incontinence. Available at http://en.wikipedia.org/wiki/Urinary_incontinence. Accessed on Nov 10, 2010.
  4. Shuttleworth KED. Incontinence. British Medical Journal 1970;4:727-729.
  5. Walid MS, Heaton RL. Stepwise Multimodal Treatment of Mixed Urinary Incontinence with Voiding Problems in a Patient with Prolapse. Journal of Gynecologic Surgery 2009; 25 (3): 121-127.
  6. Mills W, Grennland JE, McMurray G. Studies of the pathophysiology of idiopathic detrusor instability: the physiologic properties of detrusor smooth muscle and its pattern of instability. J Urol. 2000;163(2):646-51.
  7. Wein AJ, Rackley RR. Overactive bladder: a better understanding of pathophysiology, diagnosis and management. J Urol. 2006;175 (3 pt 2):s5-10.
  8. Nazir T, Khan Z, Barber HR. Urinary incontinence. Clin Obstet Gynecol. 1996;39(4):906-11.
  9. [Guideline] American College of Obstetricians and Gynecologists. Urinary incontinence in women. Obstet Gynecol. 2005;105(6):1533-1545.
  10. [Guideline] Rogers RG. Clinical practice: urinary stress incontinence in women. N Engl J Med. 2008; 358:1029-1036.
  11. Gibbs CF, Johnson TM 2nd, Ouslander JG. Office management of geriatric urinary incontinence. Am J Med. 2007;120(3):211-220.
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