Because the symptoms of Interstitial Cystitis are similar to those of other disorders of the urinary system, and because there is no definitive test to identify Interstitial Cystitis, doctors must rule out other conditions before considering a diagnosis of Interstitial Cystitis. Among these disorders are urinary tracts or vaginal infections, bladder cancer, bladder inflammation or infection caused by radiation to the abdomen, eosinophilic and tuberculous cystitis, kidney stones, endometriosis, neurological disorders, sexually transmitted diseases, low-count bacteriuria, and, in men, chronic bacterial and abacterial prostatitis.
Medical tests that help identify other conditions include a urinalysis, urine culture, cystoscopy, and biopsy of the bladder wall and, in men, laboratory examination of prostate secretions.
Urinalysis and Urine Culture
These tests can detect and identify the most common organisms in the urine that may be causing symptoms. There are, however, organisms such as the bacteria Chlamydia that can't be detected with these tests, so a negative culture does not rule out all types of infection. A urine sample is obtained either by catheterization or by the "clean catch" method. For a "clean catch," the patient washes the genital area before collecting urine "midstream" in a sterile container. White and red blood cells and bacteria in the urine may indicate an infection of the urinary tract, which can be treated with an antibiotic. If urine is sterile for weeks or months while symptoms persist, a doctor may consider a diagnosis of Interstitial Cystitis.
Culture of Prostate Secretions
In men, the doctor will obtain prostatic fluid from the patient. This fluid will be examined for signs of an infection, which can be treated with antibiotics.
Cystoscopy Under Anesthesia With Bladder Distension
During cystoscopy to diagnose Interstitial Cystitis, the doctor uses a cystoscope--an instrument made of a hollow tube about the diameter of a drinking straw with several lenses and a light--to see inside the bladder and urethra. The doctor will also distend or stretch the bladder to its capacity by filling it with a liquid or gas.
Because bladder distension is painful in Interstitial Cystitis patients, before the doctor inserts the cystoscope through the urethra into the bladder, the patient must be given either regional or general anesthesia. These tests can detect inflammation; a thick, stiff bladder wall; Hunner's ulcers; and glomerulations (pinpoint bleeding) that may be seen only after the bladder is stretched.
The doctor may also test the patient's maximum bladder capacity, the amount of liquid or gas the bladder can hold under anesthesia. Without anesthesia, capacity is limited by either pain or a severe urge to urinate. Many people with Interstitial Cystitis have normal or large maximum bladder capacities under anesthesia. However, a small bladder capacity under anesthesia helps to support the diagnosis of Interstitial Cystitis.
Biopsy
A biopsy is a microscopic examination of tissue. Samples of the bladder and urethra may be removed during a cystoscopy and examined with a microscope later. A biopsy helps rule out bladder cancer and confirm bladder wall inflammation.