Overactive Bladder (OAB)

Urinary urgency and frequent urination are symptoms of overactive bladder.

Overactive bladder (OAB) is a syndrome that is characterized by urgency to urinate, frequent urination, and urination overnight.

The bladder collects urine produced in the kidneys. The muscles that help control the ability to store and then void urine (micturition) are the muscles in the bladder wall (detrusor muscles) and the pelvic floor muscles. In the storage phase, the detrusor muscles relax and the pelvic floor muscles contract allowing the bladder to fill. When micturition occurs, the bladder muscles contract and the pelvic floor muscles relax allowing the bladder to empty.

In some people, the muscles in the bladder wall are more sensitive and the reflexes to empty the bladder occur even when the bladder is not full enough to empty. This causes the symptoms of OAB:

• urgency, the feeling that one must urinate almost immediately
• frequency of urination, or polyuria (poly=many +uria=urine)
• overnight, interferes with sleep, or nocturia (noc=night +uria)

Urgency urinary incontinence is the syndrome where OAB is associated with urinary leakage or incontinence. There is an intense urge to urinate followed by an involuntary loss of urine.

OAB affects both men and women and becomes more common as people age.

The cause of OAB is poorly understood, but involves changes in the function of the muscles. This occurs either within the muscles, or with the nerves that innervate them.

Issues with the bladder muscle itself may be due to involuntary contractions of the muscle, or the inability of the muscle to relax while the bladder fills.

With regard to potential neurologic causes, OAB is often seen in patients with spinal cord injury, herniated discs in the low back, multiple sclerosis, stroke, Parkinson’s disease, and diabetic neuropathy.

Symptoms of urgency, polyuria, and nocturia can also be seen in patients with urinary tract infections, bladder stones or tumors, prostate disease, and urethral stricture (narrowing of the tube that empties the bladder).

Common risk factors for OAB include the following:

• Age (though by itself may not be a risk factor)
• Diabetes
• Obesity
• Alcohol
• Smoking
• Use of artificial sweeteners
• Females are at higher risk
  • Multiple pregnancies
  • Vaginal delivery vs. Caesarian section
  • Post-menopausal
• Prostate disease
• Previous pelvic surgery
• Pelvic radiation therapy
• Neurologic diseases
  • Stroke
  • Spinal cord injury
  • Parkinson's disease
  • Multiple sclerosis

A variety of medications can affect urination patterns. Some examples include diuretics, angiotensin-converting enzyme (ACE) inhibitors, anticholinergic drugs, calcium channel blockers, lithium, sedatives and hypnotics, selective serotonin reuptake inhibitors (SSRIs), and opioid analgesics.

The symptoms of an overactive bladder include urgency, frequency, and urination overnight.

OAB may cause significant social and psychological issues, including always needing to know where bathroom facilities are located, and the potential and worry of urinary incontinence in public. OAB can cause depression and anxiety, affect sexual activity, impair work performance, and lead to social isolation.

The diagnosis of overactive bladder is not based on the presence of symptoms alone. Other causes need to be considered and excluded to make the diagnosis. History and physical examination, including pelvis exam in women and prostate exam in men are the initial steps. Unfortunately, the patient with OAB may not seek care for symptoms, or the healthcare provider may not ask during routine patient visits.

Urinalysis is used to check the urine for infection, blood cells in the urine, and elevated glucose (sugar) in the urine.

Bladder ultrasound is a non-invasive test to measure the amount of urine left in the bladder after urination (post-void residual).

There is a stepwise treatment for overactive bladder. It begins with physical therapy and lifestyle changes, followed by medications, and finally more aggressive options.

Initial treatment often begins with the following:

• Physical therapy exercises to strengthen a potentially weak pelvic floor muscle. Kegel exercises are an example.
• Bladder training to overcome the urgency to urinate and lengthen the times between urination.
• Biofeedback to learn how to control bladder muscle contractions.

Lifestyle changes may include:

• Addressing any medications that can increase bladder irritability
• Decreasing alcohol and caffeine intake
• Smoking cessation
• Weight loss may be helpful in controlling symptoms in the overweight patient

Medications to control OAB may be considered if physical therapy and lifestyle adjustments are not successful, or if more bladder control is needed. Two classes of medications are indicated for treatment of OAB. If needed they can be combined to potentially increase treatment benefit.

• Beta-3 agonists: May be considered as a first line medication to help stimulate smooth muscle contraction in the bladder. They have less side effects than the anticholinergic medications, but are also more expensive.
  • Mirabegron (Myrbetriq) may also be combined with solifenacin (VESIcare)
  • Vibregon (Gemtesa)
• Anticholinergics: These medications reduce smooth muscle contractions in the bladder. Side effects like dry eyes, dry mouth, and constipation are not uncommon. Examples include:
  • Oxybutynin- an antispasmodic This medication is available as a pill, a patch, or a gel.
  • Tolterodine (Detrol)
  • Fesoterodine (Toviaz)

More aggressive treatments are available if physical therapy, behavioral therapy, and medications are not helpful.

• Botulinum toxin injections into the detrusor muscle (the smooth muscle) of the bladder wall can be used to relax the muscle and help with bladder spasms. The effects decline within 6-12 month and may need to be repeated when symptoms return or increase.
• Tibial nerve stimulation. The tibial nerve is near the ankle and runs up the leg to the sacrum (the base of the spine). Stimulating this nerve can also help block the nerves that cause bladder spasms and strengthen the pelvic floor muscles. Options for this treatment include:
  • Percutaneous tibial nerve stimulation (PTNS), an office procedure where a thin wire is inserted near the nerve and electrical impulses are generated. The procedure lasts about 30 minutes and is repeated weekly for three months.
  • Transcutaneous tibial nerve stimulator, a home procedure where the electrical impulse is passed through the skin. It may be less effective than PTNS, but is an alternative for those who cannot visit the office regularly.
  • Implantable tibial nerve stimulator, a wireless device that is implanted near the ankle to deliver the electrical impulses.
• Sacral nerve stimulation (sacral nerve modulation). A device that is MRI safe can be placed in the low back (at S3 nerve root) to help control the bladder spasm.

Surgery is a last resort. Referral to a urologist is needed. Options include enlarging the bladder or placing a suprapubic catheter through the lower abdominal into the bladder to drain it.

OAB can affect quality of life, work and social function, and sleep patterns leading to anxiety, depression, and potential social isolation. There can be issues with urinary tract infections and bladder stones.

If urgency urinary incontinence is also present, there can be issues with skin breakdown and skin infections in the perineum.

The prognosis for overactive bladder is generally good. Through a combined approach of behavioral modifications and medications, most patients are able to control their symptoms and achieve an improved quality of life.

Unfortunately, for those who are elderly and frail, the side effects of medications may not be tolerated and their prognosis is less positive.