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State of the Science: Pathology and Management of the Patient with Overactive Bladder
The term overactive bladder (OAB) is defined as urinary urgency, nocturia, and frequency with or without urinary incontinence. The actual prevalence is unknown, but it is estimated to affect as many as 17 million Americans,1 with approximately 6.5 million experiencing urinary incontinence. More commonly seen in women and in those above the age of 65, OAB expands the clinical focus beyond continence to include patients coping with significant, troublesome symptoms. Of note: approximately one-half of these patients do not experience leakage of urine.2
Normal Micturition
Understanding the normal mechanism of voiding is critical to understanding the pathology and rationale for management of OAB, particularly pharmacologic treatment.
Normal voiding is the result of coordination among the central nervous system, the peripheral nervous system, nerve pathways, bladder, and sphincter. As the bladder fills, afferent (sensory) impulses are conveyed to the central nervous system at a certain level of fullness. Information is relayed through the spinal cord to the pons and cerebral cortex. The cortex provides for social continence, delaying voiding until socially acceptable. The pons is responsible for coordination of urination by mediating the autonomic nervous system response. It is theorized that the pons has two separate areas for micturition and for storage.
Voiding is initiated by activation of the parasympathetic pathways. Parasympathetic stimulation allows relaxation of the proximal urethra along with contraction of detrusor smooth muscle by release of acetylcholine (ACH) on the muscarinic postganglionic receptors.3 Sympathetic stimulation leads to bladder storage.4 Epinephrine and norepinephrine are the primary neurotransmitters for the postganglionic sympathetic nervous system. Stimulation of beta-adrenergic receptors in the bladder promotes storage by inhibiting detrusor contractions and allowing relaxation of the bladder, while stimulation of alpha-adrenergic receptors contracts the bladder neck with resulting tightening. Thus, normal voiding is dependent on intact central and peripheral nervous system structures and pathways, as well as normal bladder and sphincter function.
Theories about Pathogenesis
The cause of OAB remains unclear, but the following theories represent current thinking and research findings. Disorders of the central nervous or peripheral nervous system, altered levels of neurotransmitter, and problems with the bladder smooth muscle can all lead to OAB. Some of the causes of overactive bladder include:
* Conditions that affect the brain or spinal cord. These can result in the loss of the central nervous system's ability to inhibit bladder contractions, explaining the high prevalence of OAB in patients with cerebrovascular accidents (CVA), spinal cord injuries, multiple sclerosis, and Parkinson's disease.3 Lesions in the pontine storage center decrease the bladder's ability to store urine.
* Dysfunction of the afferent (sensory) pathways. Studies indicate that some patients became increasingly sensitive to bladder distention, sensing fullness at low volumes. These patients will complain of frequency and urgency despite low voided volumes. Frequency is another troublesome symptom of this condition.5
* Neurotransmitters such as serotonin and noradrenaline affecting function as well as mood state. A higher incidence of depression has been observed in patients with incontinence. Studies indicate that incontinence and depression commonly co-exist and that treatment of depression frequently results in improved continence as well.6
* Abnormalities in the smooth muscle of the bladder that may make the muscle more prone to inappropriate contractions.3,5 This may occur as a result of pathology or aging. Structural deformity can occur from prolonged obstruction as commonly seen in men with benign prostatic hypertrophy. Increased urethral resistance in females may result from advanced organ prolapse or as a result of bladder neck suspension.7 The obstruction causes denervation as well as changes in the bladder smooth muscle.
In summary, the etiology of OAB remains unclear. The causative factor probably varies depending on the individual, and in many cases the etiology may be multifactoral. Research is ongoing to understand the etiology and improve treatment for these patients.
Clinical Presentation
The clinical presentation of OAB is variable but several symptom patterns emerge. This condition is characterized by frequency (greater than eight voids in a 24-hour period), urgency (sudden desire to void causes abnormal sensitivity to bladder filling or overactivity of the detrusor muscle),8 and nocturia (more than two nighttime voids).9 Despite the frequency and urgency, voided volumes are low. Incontinence may or may not be present. When incontinence occurs, it presents as an urge pattern (leakage associated with sudden strong desire to void) or mixed urge and stress (strong urge to void with sudden increase in intra-abdominal pressure).
The urgency and frequency may be in response to stimuli (eg, running water, "key in lock" - the term used to describe the urgency patients experience as they fumble to get in the door to the bathroom) or may occur spontaneously with little warning to the patient.
Quality-of-life issues are significant. Many report significant curtailment of activities due to the condition and decreases in quality-of-life scores.10 Depression has been associated as both a result and possible link to etiology because of shared neurochemical pathogenesis.6 Patients with OAB without incontinence are less likely to seek medical attention than those with incontinence.11 Healthcare providers need to become more knowledgeable in recognizing OAB to appropriately manage these patients.
Assessment of the Patient with OAB
History. A thorough and accurate history and physical examination are integral components of assessing OAB. Critical information to obtain includes:
* Chief complaint - current symptoms, severity, exacerbating and relieving factors
* Neurologic history - history of CVA, Parkinson's disease, multiple sclerosis, diabetic neuropathy
* Urologic history - history of frequent urinary tract infections, genitourinary or pelvic surgery, sexual dysfunction, gynecologic surgeries, menopausal status
* Psychiatric history - specifically, depression
* Gastro-intestinal history - bowel habits, (including constipation), surgeries
* Medications - include all prescription and over-the-counter medications.
All patients should be evaluated for reversible factors. Constipation, inadequate or excessive fluid intake, and a diet laden with known bladder irritants all may contribute to OAB.
Bladder diary. The value of a 3-day voiding diary should not be underestimated. Daily average output, functional bladder capacity, voiding intervals, and patterns of leakage are ascertained from this simple document. Functional bladder capacity is the amount of urine stored in the bladder before a sense of fullness, urgency, or urinary leakage prompts the individual to urinate.9 Patients can incorporate a record of the amount and type of fluids consumed as they keep the voiding diary to bring to light problems with bladder irritants.
Physical examination. A focused physical examination is an essential part of the OAB assessment (see Table 1).9 Abdominal, pelvic, and neurological examination is performed, and other systems should be examined based on the patient's history.12
The complete assessment should include a urinalysis, and a post-void residual assessment should be considered when the patient's history suggests retention. Many conditions are associated with retention, such as benign prostatic hypertrophy, prolapse, multiple sclerosis, and diabetes mellitus.9 It is not unusual for patients with retention to experience urgency and frequency, so the clinical presentation can be similar to OAB. As noted in pathogenesis, obstruction also has been linked to OAB. Ideally, the patient should void into a flowmeter to determine urine flow rate and pattern, and then be catheterized to determine the residual volume. The catheterized urine is examined with urine dipstick or under the microscope. Urine dipstick testing is relatively inexpensive and analyzes urine for nitrites and leukocytes, which indicate infection.12 The presence of hematuria and proteinuria warrants referrals to rule out underlying serious medical conditions.
Management Options
Overactive bladder management options include lifestyle changes, behavioral therapies, pharmacologic agents, and neuromodulation therapy. Treatments are often combined (particularly behavior and medication) - a strategy that has been found to be effective for many patients.13 Initial focus is on managing reversible or transient factors and initiating behavioral interventions. Medical management and neuromodulation are employed when behavioral techniques are not successful.
Behavioral interventions. Behavioral therapy is the first management strategy in treating OAB, as it addresses many of the transient factors that can exacerbate this condition. Therapies include: lifestyle/dietary changes, pelvic floor muscle exercises, and bladder retraining. One controlled study demonstrated an 80.7% reduction in incontinent episodes with behavioral therapy, compared with a 68.5% reduction in those treated with medication.14 Although often referred to as "simple changes," lifestyle changes are undoubtedly the hardest changes to make.
Patients need to understand how to manage their fluid intake. Daily recommended intake is six to eight 8-oz glasses of fluid. Fluid intake should be encouraged during the waking hours and restricted after 6:00 p.m. or 7:00 p.m. Dietary changes involve avoiding known bladder irritants such as alcohol, caffeine, very acidic fruits and juices, tomatoes and tomato-based foods, carbonated drinks, and artificial sweeteners.
Bowel management strategies work to eliminate constipation. Although constipation does not cause OAB, rectosigmoid distention can be an exacerbating factor. By relieving the pressure of a colon full of stool on the bladder, the bladder has much more room and is less apt to contract involuntarily. Increased fiber in the diet, fiber supplements, stool softeners, and laxatives may all play an important role in bowel management for the patient with OAB.
Two of the most difficult changes for patients to make are smoking cessation and weight reduction. These changes can help relieve the symptoms of OAB by eliminating the irritant effect of nicotine in tobacco and relieving the pressure from increased body girth. Patients need extra emotional support and encouragement to be successful "quitters and losers."
Bladder training can help patients regain control by using urge inhibition techniques to help them delay voiding until they are ready to use the toilet. Information about voiding intervals obtained from the voiding diary helps the practitioner establish a routine where the patient is instructed to "void by the clock" and use distraction/inhibition techniques between designated voiding times. Once patients have comfortably mastered the initial time interval that has been set, it is increased by 15 minutes. This pattern is repeated until the patient can go 21/2-to-3 hours between voids.
Pelvic floor muscle exercises or Kegel exercises help strengthen the pelvic floor so when the patient experiences an involuntary detrusor contraction, he or she can close the urinary sphincter by contracting the pelvic floor muscles. Learning how to isolate and properly exercise the pelvic floor can be confusing at first and should be incorporated into the pelvic exam. Once the sensation of a properly performed Kegel is realized, the patient should be able to perform these exercises without difficulty.
Biofeedback is often used in conjunction with Kegel exercises. Biofeedback uses sensors in the vagina or rectum and on the abdomen to read electrical signals that result when muscles are contracted and relaxed. These signals are transformed so they can be seen as waveforms on a computer monitor, reinforcing proper contraction of the correct muscle group.
Electrical stimulation, or E-stim, uses similar equipment and sensors. With E-stim, a small electrical current is passed through the pelvic floor muscles. This stimulation helps reduce the involuntary bladder contractions of OAB and strengthen the pelvic floor muscles so patients can contract and close the urinary sphincter when they begin to sense the urge to urinate.15
Another nonsurgical treatment option, extracorporeal magnetic innervation (ExMI), produces a highly focused, therapeutic magnetic pulse wave. Just as an electric current induces a magnetic field, a changing magnetic field induces a electric field and can be used to stimulate the sacral nerves.15 With each pulse, the patient's pelvic floor contracts then relaxes. The practitioner controls the strength and duration of each magnetic pulse and contraction. Patients are fully dressed and comfortable while sitting on the ExMI chair. A recent study of 48 patients showed improvement in symptoms, noting an increase volume per void, a decrease in the number of leaks, and overall increase in quality-of-life survey in the active treatment group.16
Neuromodulation therapy. A more invasive therapy called InterStim® (Medtronic Inc., Minneapolis, Minn.) is available for patients who have essentially failed pharmacologic and conservative treatments. The implantable device uses mild electrical stimulation of the sacral nerve that innervates the bladder, sphincter, and pelvic floor muscles. This treatment has been effective in reducing or eliminating the symptoms of OAB in patients who have not responded to other therapies. The procedure is carried out in two stages. Initially, a test stimulation is performed that allows the patient to experience the effect of therapy for approximately 3 to 5 days. Test stimulator leads are inserted through the lower back near the appropriate sacral nerve. Once the proper location is found, the lead is taped in place and a test stimulator connected to the lead with a cable. This stimulator is usually worn on the belt or waistband for the next several days to a week. If the test stimulation is successful in controlling the symptoms of urgency, frequency, and urge incontinence, a permanent neurostimulator is surgically implanted. External programmers are used to turn the device on and off and to adjust levels of stimulation as needed. The long-term results of a prospective longitudinal study by Bosch and Groen17 demonstrate that neuromodulation is effective in patients with detrusor instability and should be offered if conservative measures have failed.
Pharmacotherapy. Several medications can be helpful in the treatment of OAB. In postmenopausal women, topical estrogen cream helps improve urethral resistance and reduce bladder contractility.18
Antimuscarinics such as oxybutynin (Ditropan, Ditropan XL, Ortho-McNeil, Raritan, NJ) and tolterodine (Detrol, Detrol LA, Pharmacia and Upjohn, Peapack, NJ) are the primary drugs of choice. They work by blocking the muscarinic receptors that mediate bladder contractions. Unfortunately, the side effects of dry mouth, blurred vision, and constipation can be quite severe and result in the discontinuation of the medication.
Tolterodine has a greater affinity for bladder receptors than for salivary receptors and should cause fewer oral problems than oxybutynin.18
A drug that is used infrequently but still may be encountered in clinical practice is imipramine (Tofranil, Novartis, East Hanover, NJ), a tricyclic antidepressant. Its anticholinergic effects inhibit bladder contractility, but also produce troublesome side effects such as postural hypotension, limiting its effectiveness.
Drugs that target central and peripheral nervous systems without the side effects of the antimuscarinics may prove promising.19 Bladder afferents such as resiniferatoxin have helped spinal cord injured patients with incontinence.20 Botox (Allergan, Irvine, Calif.) has shown effectiveness in decreasing symptoms of OAB by binding to cholinergic receptor sites.21 Transdermal delivery of oxybutynin has shown effective at reducing symptoms and improving quality of life.22
Conclusions
An understanding of the symptoms of OAB by the healthcare provider is essential. Researchers note that OAB may be the result of neurologic disorders, smooth muscle abnormality, or structural abnormality, and treatment should be aimed at correcting these conditions. Research into the effect of magnetic therapy and the impact of counseling and support on behavioral changes may provide relief to the millions with this condition. Investigations to develop medications with lower side effect profiles and different delivery systems continues. Questioning the patient to determine incidence will enable early, possibly simpler interventions. Recognition and early treatment will have a significant impact on the health and quality of life for patients with OAB. - OWM
CME Quiz
How to obtain 2.0 Continuing Education contact hours by reading this article Instructions: Registered nurses may receive 2.0 contact hours by reading the article noted below and successfully answering the questions in the following post-test. To obtain continuing education contact hours:
1. Read the article "State of the Science: Pathology and Management of the Patient with Overactive Bladder" carefully, noting the tables and other illustrative materials that are provided to enhance your knowledge and understanding of the content.
2. Download a PDF of the CE Answer Form. Read the questions and, on your copy of the answer form, circle the letter that best answers each question.
3. Carefully fill out your information in the spaces provided on the answer form.
4. Fax completed form to: (610) 560-0502 or mail the form to:
Trish Levy, Director Medical Education
HMP Communications
83 General Warren Blvd. #100
Malvern, PA 19355
Accreditation Statement: This activity for 2 contact hour(s) is provided by HMP Communications, LLC. Provider approved by the California Board of Registered Nursing, Provider Number 13255.
Target Audience: Nurses
Method of Participation: Nurses may receive 2 contact hour(s) by reading the article and successfully answering the questions in the post-test. A score of 70% is a passing score. Certificates will be mailed to participants within 60 days of receipt of your test and evaluation form.
Contact hour units received for successful completion of the post-test may be used for certification or recertification credit.
Objectives: After reading the article, "State of the Science: Pathology and Management of the Patient with Overactive Bladder," the reader will be able to:
1. Describe normal micturition
2. List three theories about pathology of overactive bladder (OAB)
3. Discuss three management options for the patient with OAB.
From the choices offered for each question, select the one best response.
1. The following represents the primary symptoms of overactive bladder (OAB):
A. Urgency, frequency, nocturia, with possible leakage of urine
B. Urgency, frequency, nocturia, always accompanied by urine loss
C. Leakage associated with complete loss of urine
D. Sudden feeling of urge associated with complete loss of urine
2. Which of the following is NOT considered a cause of OAB?
A. Central nervous system disorders
B. Abnormalities of the smooth muscle of the bladder
C. Dysfunction of the sensory pathways
D. Chronic renal failure
3. Behavior interventions include all of the following EXCEPT:
A. Dietary changes
B. Kegel exercises
C. Fluid restrictions
D. Bladder retraining
4. Which of the following conditions may present similarly to OAB?
A. Stress incontinence
B. Urinary retention
C. Reflex incontinence
D. Chronic renal failure
5. Known bladder irritants include:
A. Alcohol, caffeine, artificial sweeteners
B. Bananas, leafy green vegetables, salt
C. Dairy products, carbohydrates, and water
D. Poultry, seafood, and sugar
6. First line treatment for OAB should be:
A. medication
B. neuromodulation
C. behavior changes
D. biofeedback
7. Biofeedback is used to:
A. increase urethral resistance
B. interrupt sacral stimulation of the bladder
C. help the patient identify correct muscle group to exercise
D. increase bladder capacity
8. Antimuscarinics are effective in the treatment of OAB because they:
A. block muscarinic receptors that mediate bladder contractions
B. increase bladder capacity
C. increase bladder contractions
D. increase urethral resistance
9. The following are common side effects of antimuscarinic medications:
A. increased heart rate and blood pressure
B. diarrhea and fatigue
C. urinary retention
D. dry mouth and constipation
10. Estrogen is used in women with OAB to:
A. increase pelvic muscle strength
B. increase urethral resistance and reduce bladder contractility
C. decrease bladder capacity
D. improve levels of neurotransmitters
Yes or No:
1. Content was current and relevant.
2. Content will have a positive impact on my professional effectiveness.
3. Home study was an appropriate format for the content.
4. The content met my educational needs.
5. Now that you have read this article, can you:
A. Describe normal micturition?
B. List three theories about pathology of overactive bladder (OAB)?
C. Discuss three management options for the patient with OAB?
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