NIH Definition & Classification


Prostatitis is a common cause of visits to primary care physicians and urologists. In practice, the clinical diagnosis of prostatitis depends on the history and physical examination, but there is no characteristic physical finding or diagnostic laboratory test. Patients with prostatitis experience considerable morbidity and may remain symptomatic for many years. Unfortunately, there is limited understanding of the pathophysiology and optimal treatment for most patients.

To improve diagnosis and treatment of prostatitis, the National Institutes of Health (NIH) established an International Prostatitis Collaborative Network. This group evaluated the literature and clinical practice and convened 2 consensus conferences (1 in 1995 and in 1998) to establish a new definition and classification of prostatitis syndromes. This consensus classification will serve as the framework for international studies to determine the causes and optimal strategies for patient management.

The NIH consensus classification of prostatitis syndromes includes 4 categories:

  1. Acute bacterial prostatitis
  2. Chronic bacterial prostatitis
  3. Chronic prostatitis/CPPS
    1. Inflammatory
    2. Noninflammatory
  4. Asymptomatic inflammatory prostatitis

Chronic nonbacterial prostatitis/CPPS has not been scientifically demonstrated to be primarily either a disease of the prostate or the result of an inflammatory process.

Diagnostic Criteria for NIDDK-Sponsored Research Studies

The following criteria were approved for research studies on chronic nonbacterial prostatitis/CPPS.

Inclusion Criteria

  • male, at least age 18
  • pain or discomfort in the pelvic area (penis, scrotum, perineum, or thereabouts) for at least 3 months

Exclusion Criteria

  • the presence of cancer of the genitourinary tract
  • active urinary stone disease
  • herpes of the genitourinary system
  • bacteriuria (100,000 colonies in a midstream urine) within the past 3 months
  • antibiotic therapy within the past 3 months
  • peri-rectal inflammatory disorders
  • inflammatory bowel disease
  • history of pelvic radiation or systemic chemotherapy
  • history of intravesical chemotherapy
  • documented gonorrhea, chlamydia, mycoplasma, or trichomonas infection of the urinary tract within the past 3 months
  • clinical epididymitis within the past 3 months
  • urethral stricture of 12 French or smaller
  • neurological disease or disorder affecting the bladder
  • prostate surgery (not including cystoscopy) within the past 3 months

Patients with acute bacterial prostatitis present with acute symptoms of a urinary tract infection, characteristically including urinary frequency and dysuria. Some patients have symptoms suggestive of systemic infection, such as malaise, fever, and myalgias. Bacteriuria and pyuria are related to infection of the prostate and bladder caused by well-recognized uropathogenic bacteria, especially Escherichia coli.

Patients with chronic bacterial prostatitis experience recurrent episodes of bacterial urinary tract infection caused by the same organism, usually E coli, another Gram-negative organism, or enterococcus. Between symptomatic episodes of bacteriuria, lower urinary tract cultures can be used to document an infected prostate gland as the focus of these recurrent infections. Acute and chronic bacterial prostatitis represent the best understood, but least common, prostatitis syndromes.

More than 90% of symptomatic patients have chronic prostatitis/chronic pelvic pain syndrome. This new term recognizes the limited understanding of the causes of this syndrome for most patients and the possibility that organs other than the prostate gland may be important in the cause of this syndrome. The new consensus definition recognizes urological pain complaints as a primary component of this syndrome and includes several exclusion criteria (such as presence of active urethritis, urogenital cancer, urinary tract disease, functionally significant urethral stricture, or neurological disease affecting the bladder). Patients with the inflammatory subtype of chronic prostatitis/chronic pelvic pain syndrome have leukocytes in their expressed prostatic secretions, postprostate massage urine, or semen. In contrast, patients with the noninflammatory subtype have no evidence of inflammation.

Asymptomatic inflammatory prostatitis is diagnosed in patients who have no history of genitourinary tract pain complaints. Such patients are usually diagnosed during evaluation for other genitourinary tract issues. For example, many men undergo prostate biopsy for evaluation for possible prostate cancer because of an elevated serum prostate-specific antigen level. Prostatitis is the most common noncancer diagnosis (based on histological criteria) in these men. Other asymptomatic patients undergo evaluation for infertility. Excess concentrations of leukocytes in the seminal fluid are a common finding in such patients.

This working definition and classification of prostatitis syndromes reflects a new interest in these disorders by researchers that we hope will result in improved approaches to clinical diagnosis and patient management.

John N. Krieger, MD University of Washington Seattle
Leroy Nyberg, Jr, PhD, MD National Institute of Diabetes and Digestive and Kidney Diseases Bethesda, Md
J. Curtis Nickel, MD Queen’s University Kingston, Ontario For the International Prostatitis Collaborative Network