Overactive Bladder (OAB) Etiology & Clinical Assessment

The overactive bladder (OAB) is a prevalent problem, with considerable effects on the quality of life of affected individuals and substantial health economic costs.

The condition is symptom based and defined by the International Continence Society (ICS) standardization committee as urgency, with or without urgency incontinence, usually with frequency and nocturia, if there is no proven infection or other obvious pathology.

  • Urgency with at least one other symptom is essential to diagnose OAB.
  • Urgency is the central symptom, defined by the ICS as the complaint of a sudden compelling desire to void that is difficult to defer.
  • The normal urge to void is terms the desire to void, by the ICS and is used to describe normal filling sensation.
  • Urgency incontinence is defined as involuntary leakage of urine, accompanied or immediately preceded by urgency.
  • The symptom of “increased daytime frequency” is the complaint by the patient who considers that they void too often throughout the day.
  • Although the ICS has not defined normal daytime voiding frequency, many references and clinical trials have reported baselines of 8 - 10 daytime voids as normal. Variables include the intake of liquids and medications that may increase voiding frequency.
  • The symptom of nocturia is the complaint that the individual is awakened from sleep at night one or more times to void.

Etiology - OAB:

  • Neurologic disease is associated with a high prevalence of lower urinary tract dysfunction (LUTD).
  • OAB increases with increasing age.

Prevalence of OAB:

  • The NOBLE study established the prevalence of OAB in more than 5000 community-dwelling individuals in the United States using a validated computer-assisted telephone interview.
  • Men and women had the same prevalence of OAB overall (16.0% and 16.9%, respectively) as defined by the ICS.
  • Men were shown to have a higher prevalence of “OAB dry” (13.4% as opposed to 7.6% in women)
  • Women had a higher prevalence of “OAB wet” (9.3% as opposed to 2.6% in men).
  • In women the prevalence of “OAB wet” rose from 2.0% in the youngest group (ages 18 to 24) to 19.1% in those 65 to 74 years of age.
  • Men, on the other hand, did not experience an increase in “OAB wet” until older: 8.22% for those 65 to 74 and 10.2% for those 75 years and older.
  • Using the standardized ICS definition of OAB, the EPIC study reported the prevalence of OAB in four European countries and in Canada, reporting an overall OAB prevalence of 11.8%.
  • Both types of OAB have a significant impact on the patients’ quality of life.
  • OAB is a chronic condition, and ongoing quality of life impairment can be anticipated in many patients.

Clinical Evaluation:

  • Patients with OAB may present to health care professional in primary care, OBGYN, or urology.
  • It is critical for the healthcare professional to hear the patient defining either signs or symptoms of OAB.
  • OAB is a condition that requires management, and “cure” is not a realistic possibility. Appropriate expectations and explanation are important to the success of patient treatments.
  • An initial assessment gives a diagnosis and the basis for empirical treatment.
  • Establish the patient's desire for treatment and which therapies are open to consideration..

History to include:

  • Presence or absence, incidence, severity, and bother for each of the OAB symptoms including urgency incontinence.
  • Other lower urinary tract symptoms (LUTS) should also be assessed.
  • Presence or absence of dysuria and hematuria.
  • Nature and volume of fluid intake.
  • Whether occult neurologic disease could be present.
  • Obstetric and gynecologic history, previous surgery/radiotherapy, bowel symptoms, and drug history.
  • Other medical issues
  • Dipstick urinalysis is necessary to exclude hematuria or urinary tract infection.
  • A significant postvoid residual volume must be considered when evaluating OAB.

Symptom assessment questionnaires provide valuable information for baseline assessment and follow-up of treatment response.

  • The bladder diary is essential for assessing OAB and excluding additional problems such as polydipsia or nocturnal polyuria.
  • The OAB-q is highly responsive to change between continent and incontinent patients with OAB, and is a valid tool for measuring treatment outcomes among continent OAB patients. 

Mixed Urinary Incontinence

  • Mixed OAB is where OAB and stress urinary incontinence (SUI) are both present.
  • Mixed urinary incontinence (MUI) is the complaint of involuntary leakage associated with urgency and with exertion, effort, sneezing, or coughing.
  • The history can be helpful; the primary problem in mixed UI is often that component (the stress or the urge) that occurred first chronologically.
  • The voiding diary can provide important information on chronological order.
  • When OAB is the predominant problem the void volumes should be small both day and night.
  • If there are small daytime voids with little or no nocturia and a large first morning void the urgency symptoms tend to be a manifestation of SUI, perhaps stimulated as a few drops of urine leak into the proximal urethra with activity and trigger a sense of urgency.
  • Pelvic organ prolapse can have a similar effect. When SUI is suspected to be the primary component, a short-term trial of one of the vaginal support devices may clarify the picture.
  • If the symptoms are relieved by the device the patient may decide to continue using it or feel more confident that surgical intervention will be successful.
  • A pessary trial is doubly important before correcting pelvic organ prolapse (with or without UI).
  • Elevation of a cystocele will unmask occult sphincteric incompetence in approximately 50% of patients who are continent with the prolapse.
  • If an ambulatory trial of a pessary is not performed, then a pessary or vaginal packing may be used during preoperative urodynamic testing.
  • The urethral stent/plug devices are relatively contraindicated in this patient population because clinical experience suggests that they typically aggravate the underlying urge and become totally ineffective.

Mixed Incontinence

Mixed incontinence is the combination of urinary symptoms and fecal incontinence.

OAB-q and OAB-q short form symptom bother


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