Overactive bladder and stress urinary incontinence: From diagnosis to treatment

Overactive bladder 

OAB comprises a constellation of symptoms including urinary urgency and frequency as well as nocturia (having to wake at night one or more times to void), nocturnal enuresis (involuntary voiding), and urge urinary incontinence (see Table 2). Using the reservoir/valve model, OAB usually arises from an abnormal reservoir component. Normally, the bladder will distend to accommodate 300–500 mL of fluid before a strong need to urinate is experienced. The distended bladder also normally remains relaxed, despite being full, until a conscious decision is made to allow it to contract.

TABLE 2. Types of lower urinary tract problems and associated findings

	Type	Definition	Common complaints	Common exam findings/test results
	Stress Urinary Incontinence (SUI)	Involuntary leakage of urine from the urethra, synchronous with effort/exertion, or sneezing or coughing	“I leak when I laugh, cough or sneeze”	Voiding diary: Incontinence associated with activity not urge, normal voiding frequency
			“I leak when I stand up from my chair”	+ Cough stress test
			“I leak when I pick up my grandchild”	+ Pad test
			“I leak when I jog or do exercise”	Normal urinalysis
			“I leak when I have intercourse”	Normal PVR
				Normal office cystometry
	Overactive Bladder (OAB)	Symptoms of urgency, frequency, nocturia, and/or incontinence due to involuntary detrusor contractions	“When I gotta go, I gotta go!”	Voiding diary: Multiple entries, increased episodes of urgency (increased voiding frequency), >2 night time entries, incontinent episodes associated with urge
			“I go to the bathroom almost every hour”	+ Pad test
			“I leak on the way to the bathroom”	+ Abnormal bladder activity on office cystometry (common but not always seen)
			“If I don't make it, I'm soaked!”	± Abnormal urinalysis
			“I know where every bathroom in the mall is”	Normal PVR
			“I have to get up at least 3 times a night”
			“Sometimes I wake up already soaked”
	Overflow Incontinence	Involuntary leakage of urine associated with overdistension of the bladder	“I have absolutely no control”	PE: severe prolapse, urethral stricture/mass, abn neuro exam
			“I am constantly dribbling”	Voiding diary: Incontinence with activity, urge, or no reason, increased voiding frequency, small volume voids
			“I always feel like I have to go, but then I can't empty when I get to the bathroom”	+ Large PVR
			“I have to strain or push to empty my bladder”	+ Urinalysis (common but not always abnormal)
			“It takes a long time to start to urinate”	+ Abnormal office cystometry with decreased sensation
				and large bladder capacity
				± Cough stress test
				± Pad test

PVR, post-void residual volume

With OAB, the sensation of urgency occurs at lower volumes and can be associated with non-suppressible urinary bladder wall muscle (detrusor) contractions that cause urge incontinence. Not all women with OAB experience incontinence; however, the symptoms of urgency, frequency, and nocturia can sometimes be extremely severe and very disruptive to a woman's life. For example, some women refrain from activities where bathroom facilities are not immediately accessible, or decide not to travel because they are not able to maintain bladder control for the length of a car ride, or may feel chronically fatigued from not ever getting a restful night's sleep.

Stress urinary incontinence 

SUI is defined as involuntary leakage due to exertion and may result from coughing, sneezing, or laughing. In terms of the reservoir/valve system, an improperly functioning valve (urethra) leads to SUI.

Various factors can affect the normal functioning of the urethra—the anatomic location of the urethra and surrounding structures, appropriate innervation of the urethral musculature, and adequate blood supply to all these structures. All of these components help to compress and close off the urethra during times of exertion.

In cases of prolapse or even minor vaginal and supportive tissue relaxation, the urethra can become hypermobile and lose its ability to maintain continence during exertion. Weakness of urethral support can result from a genetic predisposition for weak connective tissue, weakened tissue with advancing age, or changes due to trauma. Trauma that can change lower urinary tract anatomy includes prior surgery, pregnancy and/or childbirth, or radiation.

Decreased pelvic muscle tone and function is also implicated in patients with SUI, by impairing adequate contraction of pelvic muscles in an appropriate response time to help maintain continence. All of the compressive actions of the urethra must be able to coordinate with the detrusor muscle, and the urethral mucosa must remain pliable and well vascularized in order to maintain its watertight seal.

Making the diagnosis 

A basic office evaluation is all that is needed to make an initial diagnosis of OAB or SUI. The genitourinary history should focus on the symptoms perceived as most bothersome and attempt to identify any reversible, non-genitourinary causes for the symptoms. The remainder of the evaluation consists of a focused genitourinary examination, urinalysis and post-void residual volume (PVR) assessment, simple cystometry, pad test, cough stress test, and review of a voiding diary. A description of each component of the evaluation follows.

The focused genitourinary examination should include evaluation of the abdominal, pelvic, and rectovaginal regions for possible masses and fistulas, prolapse, muscle strength and symmetry, along with rectal sphincter tone, rectal masses, and fecal impaction. A focused peripheral neurologic exam can evaluate the integrity of the lumbo-sacral spinal cord and pelvic nerves, both of which play an important role in bladder function. A bilateral evaluation of lower extremity motor strength and sensation and perineal sensation should also be done.

Urinalysis is performed on a voided specimen to evaluate for signs of infection. After emptying the bladder, PVR is obtained. There is no standard definition for normal and abnormal PVR volumes; however, a PVR of less than 50 mL is generally considered normal, and volumes of greater than 200 mL are generally cause for further evaluation. For a basic evaluation of LUTS, the PVR volume is used mainly to rule out overflow incontinence.

Simple cystometry is a procedure of gradually filling the bladder with distilled or sterile saline water. Two volumes are noted during the filling phase of the test, the patient's first sensation of the need to void and the volume at which the patient senses strong urgency or maximum bladder capacity. Women normally feel the first sensation to void at approximately 100–200 mL of retrograde fill. Normal maximum bladder capacity is approximately 300–600 mL of fluid. Volumes less than these values suggest a problem with impaired bladder capacity, and/or decreased bladder compliance.

At maximum bladder capacity, provocative stimuli, such as the sound of running water or coughing, can be used to try to provoke an abnormal bladder contraction. After removing the catheter, a cough stress test is then performed supine. If negative, the test is repeated standing, with cough and Valsalva.

In the pad test, the patient is asked to come to the office with a full bladder, is given an absorbent pad to wear, and then performs activities over the course of an hour that usually elicit leakage—climbing stairs, coughing, jogging in place, squatting, standing from a sitting position, and washing hands. The pad is then weighed. A weight gain of greater than 2 g per hour is considered a positive test.

The voiding diary is an important tool for evaluation of LUTS (see figure 1). Typical is a 3-day diary that asks the patient to document every void and amount of fluid intake over a 24-hour period. This tool provides information on frequency, frequency specific to time of day, frequency of incontinent episodes, precipitating factors to episodes, bladder capacity, and appropriate versus excessive fluid intake. It allows identification of polyuria/polydipsia and patients who leak because they allow their bladders to get very full (>500 mL).

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Figure 1. Voiding diary. In a typical voiding diary, the patient documents every void and amount of fluid intake for three 24-hour periods, which do not have to be consecutive days.

Treatment modalities 

OAB with or without urge incontinence 

Elimination of bladder irritants such as caffeine, tobacco, alcohol, acidic foods, and beverages may decrease symptoms. Another useful method is timed voiding, which promotes conscious control of bladder function to retrain the bladder's unconscious actions. This involves regimented voiding at designated time intervals (e.g., every 30–60 minutes) regardless of a perceived need to void. The interval between voids is gradually increased by half an hour every 3–4 days until reaching an interval that is acceptable to the patient, which is usually every 3–4 hours.

Pharmacologic therapy is a mainstay of treatment for overactive bladder and urge incontinence. Some of the more common medications are oxybutinin, tolterodine, and flavoxate (Table 3). Their mechanism of action is primarily anti-muscarinic. Blockade of muscarinic receptors in the detrusor muscle reduces involuntary bladder contractions. Common side effects are dry mouth and constipation. The drugs are contraindicated in patients with junctional arrhythmias and narrow-angle glaucoma. Although these medications are similar in function, their efficacy and side effect profile may differ by drug and by individual. It is reasonable to switch from one medication to another if a particular drug is not effective or the side effects are too bothersome.

TABLE 3. Medications used for OAB

	Drug name	Mechanism of action	Standard dosing	Side effects	Contraindications
	Oxybutinin (Ditropan) (Oxytrol patch)	Antimuscarinic, smooth muscle relaxant	5 mg bid-qid or 1 (one) patch twice weekly	Dry mouth, blurry vision, drowsiness, dizziness, headache, gastrointestinal upset	Narrow-angle glaucoma
					Unstable cardiovascular status
					GI or GU obstruction
					Myasthenia gravis
	Oxybutynin Extended-release (Ditropan XL)		5 mg qd (may increase to max of 30 mg/day)	same	same
	Tolterodine (Detrol)	Antimuscarinic, smooth muscle relaxant	2 mg bid	same	Narrow-angle glaucoma
					GI or GU obstruction
					Drug interactions with erythromycin, ketoconazole, itraconazole
	Tolterodine Long-acting (Detrol LA)		4 mg qd	same	same
	Imipramine (Tofranil)	Tricyclic antidepressant, anticholinergic, α-adrenergic agonist	25–75 mg qhs		Recent myocardial infarction
					MAO inhibitor use
					Cardiotoxic with overdose
	Flavoxate hydrochloride (Urispas)	Antimuscarinic, antispasmodic	100–200 mg tid-qid	Dry mouth, blurry vision, drowsiness, headache, gastrointestinal upset	Narrow-angle glaucoma
					GI or GU obstruction
					GI hemorrhage
	Trospium chloride (Sanctura)	Antimuscarinic, antispasmodic	20 mg bid	Dry mouth, constipation, headache	Narrow-angle glaucoma
					GI or GU obstruction/retention

Functional electrical stimulation has been found to be an effective treatment for OAB/urge urinary incontinence. This treatment stimulates the pelvic and pudendal nerves, creating a negative feedback loop that ultimately causes inhibition of abnormal bladder contractions. The treatment is administered through a vaginal or rectal device the patient can use at home.

Surgical treatment of OAB and urge UI is reserved for severe, recurrent, and refractory conditions that fail conservative management. Sacral neuromodulation (InterStim®) is a procedure involving placement of a permanent pacemaker next to the S3 nerve root.

Stress urinary incontinence 

Weight loss is believed to improve SUI by decreasing intra-abdominal pressure and reducing the threshold at which one leaks with exertion. Other important factors in controlling SUI are decreasing excessive fluid intake, decreasing caffeine intake, eliminating smoking, and timing of voids to assure an empty bladder prior to exertional events. Pelvic floor muscle training is often used to help maintain continence during times of exertion. Pessaries or even tampons can sometimes be used successfully to treat mild SUI.

Surgical procedures for treating SUI include retropubic urethropexy and pubovaginal sling. Retropubic urethropexy is performed abdominally either through a laparotomy incision or through the laparoscope. The pubovaginal sling procedures are performed vaginally and involve placing the sling under the urethra (see Figure 2, Figure 3).

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Figure 2. Anatomic location of pubovaginal slings. Perineal view with patient in lithotomy position. The traditional sling (white) is positioned at the urethrovesical junction; an alternative is to place the sling at the mid-urethra (blue). MUS, mid-urethral sling; TS, traditional sling; PB, pubic bone; U, urethra; V, vagina.

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Figure 3. Skin incisions for pubovaginal slings. The arms of the mid- urethral sling exit through two small suprapubic incisions (blue). The arms of the traditional sling exit through two slightly longer incisions in the groin (dashed lines).

The goal of these procedures is to provide a backstop to the urethra, which improves urethral valve function in the face of increases in intra-abdominal pressure. Like all surgeries, anti-incontinence procedures are also associated with the risk of untoward effects which, while rare, include persistent incontinence, infection or erosion of the sling material, urinary retention, or de novo overactive bladder symptoms.