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Nongonococcal Urethritis (NGU)
1990 Case Definition

Clinical Description

Urethral inflammation that is not the result of infection with Neisseria gonorrhoeae. Urethral inflammation may be diagnosed by the presence of one of the following criteria:

  • A visible abnormal urethral discharge (excludes scant amounts of clear mucus)
  • A positive leukocyte esterase test from men less than 60 years of age without a history of kidney disease or bladder infection, prostate enlargement, urogenital anatomic anomaly, or recent urinary tract instrumentation
  • Microscopic evidence of urethritis (greater than or equal to 5 white blood cells (WBC) per high-power field) on a Gram stain of a urethral smear

Laboratory Criteria for Diagnosis

No evidence of N. gonorrhoeae infection by culture or Gram stain

Case Classification


A clinically compatible case among males in whom gonorrhea is not found, either by culture or Gram stain


Nongonococcal urethritis is a clinical diagnosis of exclusion. The syndrome may result from infection with several agents (see Chlamydia trachomatis, Genital Infection). A clinically compatible case excluding gonorrhea and chlamydia should be classified as NGU. An illness among men that meets the case definition of NGU and C. trachomatis infection should be classified as chlamydia.