How is interstitial cystitis diagnosed?

Because symptoms are similar to those of other disorders of the urinary system and because there is no definitive test to identify IC, doctors must rule out other conditions before considering a diagnosis of IC. Among these disorders are urinary tract or vaginal infections, bladder cancer, bladder inflammation or infection caused by radiation to the pelvic area, eosinophilic and tuberculous cystitis, kidney stones, endometriosis, neurological disorders, sexually transmitted diseases, low-count bacteria in the urine, and, in men, chronic bacterial and nonbacterial prostatitis.

The diagnosis of IC in the general population is based on

Pinpoint bleeding on the bladder wall

• presence of urgency, frequency, or pelvic/bladder pain
  
  
• cystoscopic evidence (under anesthesia) of bladder wall inflammation, including Hunner's ulcers or glomerulations (present in 90 percent of patients with IC)
  
  
• absence of other diseases that could cause the symptoms
  
  

Diagnostic tests that help identify other conditions include urinalysis, urine culture, cystoscopy, biopsy of the bladder wall, distention of the bladder under anesthesia, urine cytology, and, in men, laboratory examination of prostate secretions.

Urinalysis and Urine Culture

These tests can detect and identify the most common organisms that infect the urine and that may cause symptoms similar to IC. However, organisms such as Chlamydia cannot 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, the doctor may consider a diagnosis of IC.

Culture of Prostate Secretions

In men, the doctor might obtain prostatic fluid and examine it for signs of an infection, which can then be treated with antibiotics.

Cystoscopy Under Anesthesia With Bladder Distention

During cystoscopy, 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 distention is painful in patients with IC, they must be given some form of anesthesia for the procedure. These tests can detect bladder wall inflammation; a thick, stiff bladder wall; and Hunner's ulcers. Glomerulations are usually seen only after the bladder has been stretched to capacity.

The doctor may also test the patient's maximum bladder capacity--the maximum amount of liquid or gas the bladder can hold. This must be done under anesthesia since the bladder capacity is limited by either pain or a severe urge to urinate. A small bladder capacity under anesthesia helps support the diagnosis of IC.

Cytoscope

Biopsy

A biopsy is a tissue sample that is then examined under a microscope. Samples of the bladder and urethra may be removed during a cystoscopy and later examined with a microscope. A biopsy helps rule out bladder cancer.

source: http://kidney.niddk.nih.gov/kudiseases/pubs/interstitialcystitis/index.htm