History: Symptoms can range from mild discomfort, pressure, and lower abdominal (suprapelvic) tenderness to intense bladder pain, cramping with urination, frequent urination, and feeling pressure (urgency) to urinate. Pain increases as the bladder fills, causing an uncontrollable urge to urinate. In most cases, a course of antibiotics will have failed to resolve the symptoms. In severe cases, individuals may urinate more than 60 times a day, and up to 10 times during the night. Individuals may also report pain during sexual intercourse (dyspareunia). Symptoms may increase during menses. Coffee, tea, carbonated drinks, alcohol, and spicy or acidic foods may aggravate the symptoms.
Physical exam: In women, a pelvic exam is done to rule out other conditions that could cause similar symptoms, such as vaginal infection or endometriosis. In men, the urethral opening is examined for evidence of a skin lesion, swelling, or discharge. The prostate and testes are examined for swelling and tenderness and to rule out conditions such as urethritis, prostatitis, and orchitis.
Tests: Urinalysis and urine culture are performed to rule out urinary tract infection. In men, prostatic fluid is also analyzed. Interstitial cystitis is suspected if the urine culture is sterile while symptoms continue over a period of weeks or months. The definitive test for the condition is fiber-optic examination of the bladder (cytoscopy) under anesthesia. Pinpoint bleeding caused by chronic irritation as well as thickening and inflammation of the bladder wall should be identified. During the course of the cytoscopy, a tissue sample may be removed for biopsy. Microscopic examination can confirm the presence of inflammation and rule out bladder cancer.
Source: Medical Disability Advisor