Author
Lars Grimm, MD, MHS
House Staff
Department of Internal Medicine
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Editor
Bradley Fields Schwartz, DO
Professor of Urology, Director, Center for Laparoscopy and Endourology
Department of Surgery, Southern Illinois University School of Medicine
Springfield, Illinois
Disclosure: Bradley Fields Schwartz, DO, has disclosed no relevant financial relationships.
Overactive bladder (OAB) is a symptom complex characterized by urinary urgency, with or without urgency-associated urinary incontinence, in the absence of a causative infection or pathologic condition. It affects a sizeable percentage of the population and creates an enormous cost to society. Diagnosis is focused initially on identifying potentially reversible etiologies. Treatment options are varied and include behavior modifications, medications, and surgical intervention. Image courtesy of the US National Cancer Institute.
The estimated prevalence of OAB is approximately 16%, with a roughly even distribution between men and women. Women are more likely to have OAB with incontinence, while men are more likely to have OAB without incontinence. The prevalence of OAB increases with age and men are more likely to develop it later in life. Persons with insulin-dependent diabetes, depression, arthritis, and those on oral hormone-replacement therapy are at risk for the development of OAB. Selective data from one meta-analysis[1] evaluating the prevalence of OAB are shown here.
OAB has a significant quality-of-life and economic impact on those it affects. The symptoms of OAB and the coping strategies used to hide those symptoms influence interactions with friends, colleagues, and families. Fear, shame, and guilt are typically reported psychological complaints. Concerns about odor, cleanliness, and leakage during intercourse may discourage people from intimacy. Selected data from one study[2] evaluating workplace productivity in the United States are shown and demonstrate significant workplace-modifying behaviors. Patients with OAB are also at risk of developing urinary tract infections and skin infections, falls, and fractures. The estimated annual OAB-related costs in the United States total $12.6 billion, with $3 billion from long-term care facilities and $9 billion from the community setting.
The act of urination requires a coordinated effort between the central nervous system and the peripheral autonomic, somatic, and sensory afferent nerves in the lower urinary tract, bladder, and sphincter. In the normal bladder, urine is kept at low pressure until the bladder is full. During urination, urethral pressure decreases and contraction of the detrusor muscle empties the bladder. The symptoms of OAB are typically associated with inappropriate detrusor muscle hyperactivity. A cross-sectional drawing of the bladder is shown, demonstrating the various muscular layers which all must be coordinated for proper bladder function.
OAB is a multifactorial disorder in both etiology and pathophysiology. The strict definition requires that no underlying condition or infection be responsible. This requires OAB to be idiopathic by definition. However, many different conditions have been identified that can cause OAB symptoms. Depending on the etiology, these conditions are potentially treatable. Common etiologies of OAB symptoms are shown by subtype.[3]
The diagnosis of OAB begins with an evaluation of a patient's symptomatic profile to ensure that it is consistent with a diagnosis of OAB. Symptoms of OAB include urge incontinence, urgency, frequency, dysuria, and nocturia. The simple urge to void is a normal sensation, but urgency is defined as a sudden compelling desire to urinate that is difficult to defer. Urinary frequency is defined as voiding 8 or more times in a 24-hour period and nocturia is defined as the need to wake 1 or more times per night to void. Key features to assess on the initial history and physical examination are shown.
Although in most cases the clinical history and physical examination can clarify the diagnosis of OAB, a number of different procedures have been developed to help confirm OAB or rule out other potential etiologies. Postvoid residual volume testing can rule out dysfunctional voiding. Urodynamic testing evaluates the storage and emptying phases of the bladder. Measurements of urine flow; pressures in the detrusor, vesicle, and abdomen; and electromyography of the urethral sphincter can be used to assess a number of different variables in real time. Cystometry may also be incorporated and refers to urodynamic investigation of the filling component of bladder function by infusing saline into the bladder. The image shown is from a urodynamic study demonstrating detrusor overactivity as evident by the detrusor pressure spike (arrow shown) during low volume and without associated urine flow. Urodynamic testing is typically reserved for patients who are refractory to therapy or for whom potential therapy may have significant side effects.
Numerous therapeutic options are available for patients with OAB. Behavioral therapy, medications, and surgery may all be used on a case-by-case basis. In general, the least invasive or dangerous therapeutic option should be tried first, which is typically behavioral therapy. Success rates for behavioral therapy are typically very good, with symptomatic reduction of 50%-80%. Combination therapy with behavioral and pharmacologic therapy may provide additional relief to individuals refractory to behavioral therapy alone. Surgery is rarely performed and is reserved for patients who are severely debilitated and who have an unstable bladder.
Pelvic floor muscle therapy exercises, or Kegel exercises, are designed to improve the function of the pelvic floor muscles in women. The rationale is that the contraction of these muscles can reflexively or voluntarily inhibit contraction of the detrusor muscle. Patients need to be taught by either a doctor, nurse, or specially trained physical therapist to learn which muscles to squeeze. The exercises can then be performed anywhere. Typically after about 6-8 weeks, individuals will notice a reduction in the number of leaks and better bladder control. Image courtesy of the National Institute of Health.
Biofeedback is a form of learning in which the patient is retrained on a specific action using a closed feedback loop. Taking normally unconscious physiologic processes and presenting them in a manner that is directly appreciable to the patient creates a system in which the patient can objectively see the response that their actions are having. Using either cystometric or electromyographic measurements, patients with OAB can be trained to exert control on their detrusor muscle, which is normally subconsciously controlled. Selected data from a study[4] comparing pelvic floor muscle therapy, biofeedback with pelvic floor muscle therapy, and electrical stimulation are shown. The biofeedback group showed significant improvement in quality-of-life scores, comparable to that of electrical stimulation and much better than with exercises alone. One of the downsides of biofeedback is the amount of focused time it takes in multiple sessions for both the patient and teacher to properly develop control.
Augmentation cystoplasty is a surgical procedure performed in patients who lack adequate bladder capacity or detrusor compliance. It is typically reserved for individuals with severe symptoms refractory to medical and behavior-modifying therapy. The procedure involves the resection of a portion of the bowel, typically the ileum or large intestine, with subsequent anastomosis to the urinary bladder to increase the total bladder volume (shown). Patients typically tolerate the procedure well but are at risk for perforation, kidney or bladder stone formation, electrolyte disturbances, and infections.
Author
Lars Grimm, MD, MHS
House Staff
Department of Internal Medicine
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Editor
Bradley Fields Schwartz, DO
Professor of Urology, Director, Center for Laparoscopy and Endourology
Department of Surgery, Southern Illinois University School of Medicine
Springfield, Illinois
Disclosure: Bradley Fields Schwartz, DO, has disclosed no relevant financial relationships.
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