(See also Overview of Voiding.)
Incidence of interstitial cystitis is unknown, but the disorder appears to be more common than once thought and may underlie other clinical syndromes (eg, chronic pelvic pain). Whites are more susceptible, and 90% of cases occur in women.
Cause is unknown, but pathophysiology may involve loss of protective urothelial mucin, with penetration of urinary potassium and other substances into the bladder wall, activation of sensory nerves, and smooth muscle damage. Mast cells may mediate the process, but their role is unclear.
Interstitial cystitis is initially asymptomatic, but symptoms appear and worsen over years as the bladder wall is damaged. Suprapubic and pelvic pressure or pain occurs, usually with urinary frequency (up to 60 times/day) or urgency. These symptoms worsen as the bladder fills and diminish when patients void; in some people, symptoms worsen during ovulation, menstruation, seasonal allergies, physical or emotional stress, or sexual intercourse. Foods with high potassium content (eg, citrus fruits, chocolate, caffeinated drinks, tomatoes) may cause exacerbations. Tobacco, alcohol, and spicy foods may worsen symptoms. If the bladder wall becomes scarred, bladder compliance and capacity decrease, causing or worsening urinary urgency and frequency.
Diagnosis is suggested by symptoms after testing has excluded more common disorders that cause similar symptoms (eg, urinary tract infections, pelvic inflammatory disease, chronic prostatitis or prostatodynia, diverticulitis).
Cystoscopy is necessary and sometimes reveals benign bladder (Hunner) ulcers; biopsy is required to exclude bladder cancer. Assessment of symptoms with a standardized symptom scale or during intravesical potassium chloride infusion (potassium sensitivity testing) may improve diagnostic accuracy but is not yet routine practice.
In addition to lifestyle modification, bladder training, drugs, intravesical therapies, and surgery are used as needed. Stress reduction and biofeedback (to strenghten pelvic floor muscles, eg, with Kegel exercises) may help. No treatment has been proved effective, but a combination of ≥ 2 nonsurgical treatments is recommended before surgery is considered.
The most commonly used drug is pentosan polysulfate sodium, a heparin-like molecule similar to urothelial glycosaminoglycan; doses of 100 mg orally 3 times a day may help restore the bladder’s protective surface lining. Improvement may not be noticed for 2 to 4 months. Intravesical instillation of 15 mL of a solution containing 100 mg of pentosan or 40,000 units of heparin plus 80 mg of lidocaine and 3 mL of sodium bicarbonate may benefit patients unresponsive to oral drugs. Tricyclic antidepressants (eg, imipramine 25 to 50 mg orally once a day) and NSAIDs in standard doses may relieve pain. Antihistamines (eg, hydroxyzine 10 to 50 mg once before bedtime) may help by directly inhibiting mast cells or by blocking allergic triggers.
Dimethyl sulfoxide instilled into the bladder through a catheter and retained for 15 minutes may deplete substance P and trigger mast cell granulation; 50 mL every 1 to 2 weeks for 6 to 8 weeks, repeated as needed, relieves symptoms in up to one half of patients. Intravesical instillation of bacille Calmette-Guérin (BCG) and hyaluronic acid are under study.
Bladder hydrodistention, cystoscopic resection of a Hunner ulcer, and sacral nerve root (S3) stimulation help some patients.
Surgery (eg, partial cystectomy, bladder augmentation, neobladder, and urinary diversion) is a last resort for patients with intolerable pain refractory to all other treatments. Outcome is unpredictable; in some patients, symptoms persist.
Interstitial cystitis is noninfectious bladder inflammation that tends to cause chronic pelvic pain and urinary frequency.
Diagnosis requires exclusion of other causes for symptoms (eg, UTIs, pelvic inflammatory disease, chronic prostatitis or prostatodynia, diverticulitis), cystoscopy, and biopsy.
Cure is rare, but up to 90% of patients improve with treatment.
Treatments can include diet modification, bladder training, and drugs (eg, pentosan polysulfate sodium, tricyclic antidepressants, NSAIDs, dimethyl sulfoxide instillation).
Surgery is a last resort for patients with intolerable pain refractory to all other treatments.