Male Urethritis Workup

Updated: Apr 08, 2016
  • Author: Michael C Plewa, MD; Chief Editor: Erik D Schraga, MD  more...
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Workup

Laboratory Studies

Because gonorrhea and chlamydia are reportable to the state health departments in the United States, [35, 36, 37] confirmatory diagnostic testing is recommended. Options include Gram stain, culture, direct immunofluorescence, enzyme immunoassay, polymerase chain reaction, nucleic acid hybridization, or nucleic acid amplification testing (NAAT), with the latter being the most sensitive.

When urine testing (see below) is not available, urethral swab specimen may be obtained by inserting a Dacron or calcium alginate swab a centimeter into the urethra and gently twisting. Testing of the discharge itself is less sensitive and not recommended. The sensitivity of urethral swab testing is diminished by recent voiding.

Gram stain microscopy may not be necessary if the patient will be treated empirically for both GCU and NGU. Gram stain microscopy with gram-negative intracellular diplococci indicates gonococcal infection. A negative Gram stain usually indicates NGU, but it does not completely exclude gonococcal infection. [38]

The presence of more than 5 WBC per oil immersion field on Gram stain of urethral secretions secures the diagnosis of urethritis. However, this classic cutoff of 5 WBC has sensitivity for infection by Neisseria gonorrhoeae, Chlamydia trachomatis, and Ureaplasma urealyticum of 80%, 23%, and 11%, respectively. [38] Some suggest the use of the presence of 2 or more polymorphonucleocytes per high-power field to diagnose urethritis. [39]

Urine Testing

Nucleic acid amplification testing (NAAT) of a urine specimen is the most sensitive test (in a male) for gonorrhea or chlamydia. Sensitivity of NAAT testing for chlamydia is optimized by waiting a minimum of 20 minutes after a recent void, [40] although prior experts recommended a 1-hour wait.

A first-void urine specimen with positive leukocyte esterase or ≥10 white blood cells per high power field is sensitive for urethritis, but this result may also occur with cystitis, pyelonephritis, and prostatitis. Leukocytes are commonly absent in midstream specimens in patients with GCU as well as even first-void specimens from patients with NGU. Leukocyte esterase testing may be as accurate as a urethral smear in asymptomatic partners in STD clinics.

Urinalysis may also visibly identify T vaginalis infection, although culture or PCR assay are more sensitive, and multiple specimens may be necessary for confirmation. [41] Because of the high transmission rate, male sex partners of infected women can be presumed to also carry T vaginalis. PCR testing for M genitalium may be available in research settings and some countries, [16] but is not yet universally available. [7]

Screen for HIV and syphilis serology (Venereal Disease Research Laboratory [VDRL] test or rapid plasma reagin test).

For refractory urethritis, consider culture of urethral secretions or first-void urine for T vaginalis.

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Procedures

Gram stain of the urethral discharge is useful to secure the diagnosis as well as to determine GCU, but this test may no longer be considered essential, since the results usually do not alter therapy.

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