Urethritis

Department of the Navy
Bureau of Medicine and Surgery

Urethritis represents one of the more common syndromes seen by the general medical officer. It consists of urethral discharge, dysuria, and evidence of a urethral polymorphonuclear leukocytosis. It implies urethral inflammation or infection and is usually sexually acquired.

Urethritis is classified as either gonococcal urethritis (GCU) if caused by Neisseria gonorrhoeae, or as nongonococcal urethritis (NGU) if caused by other infectious etiologies. The term nongonococcal urethritis (NGU) is more appropriate than the older term nonspecific urethritis (NSU), since there are specific causes for NGU. Chlamydia trachomatis or Ureaplasma urealyticum are the most frequent causes of NGU. Postgonococcal urethritis (PGU) is nongonococcal urethritis occurring shortly after therapy for urethral gonorrhea and is usually due to Chlamydia trachomatis.

Gonococcal vs Non-gonococcal Urethritis

Nongonococcal urethritis occurs more frequently than gonococcal urethritis worldwide. Although the clinical spectrum of gonococcal urethritis and non-gonococcal urethritis differ, there is often so much overlap that any differentiation cannot be based reliably on clinical features alone. For example, dysuria and urethral discharge is common in both gonococcal and non-gonococcal urethritis. However, a thick, purulent discharge present at the meatus strongly suggests GCU, especially when spontaneous or copious. A clear or scant urethral discharge suggests NGU. The incubation period for gonorrhea is usually shorter than for non-gonococcal urethritis.

The majority of men with gonorrhea develop symptoms within 4 days, while those with NGU develop symptoms within 7 to 21 days. Gonorrhea may occur as an asymptomatic infection in 1 to 10 percent of the cases in men and in as many as 50 percent of the cases in women. Non-gonococcal urethritis may be asymptomatic in up to 25 percent of infected men (5-10 percent in young active duty men), and in over 50 percent of infected women.

Diagnosis of Urethritis

The diagnosis of urethritis should be based upon both a physical exam and microscopic assessment of the urethral material. It is preferable to examine the patient at least 2 hours after micturition or before their first morning void. The patient should provide a first morning void and the first 10 to 15 cc. of the urine is saved. It is centrifuged so that the sediment may be analyzed microscopically under high power or oil immersion field. The presence of 10 or more polymorphonuclear leukocytes seen under high power is suggestive of urethritis.

Next, any discharge present at the meatus is easily recovered for examination. If a discharge is not present, the urethra should be gently stripped by placing the gloved thumb along the ventral surface of the penis with the fingers above, applying gentle pressure, and moving the thumb forward to deliver the discharge.

A gram stain is prepared and a culture obtained for N. gonorrhoea, using selective media for gonorrhea (modified Thayer-Martin, or chocolate agar). The gram stain  is examined using the oil-immersion objective of the microscope. The presence of 4 or more polymorphonuclear leukocytes (PMNs) per oil immersion field is diagnostic for urethritis. The presence of gram-negative, intracellular diplococci on gram stain establishes a diagnosis of gonorrhea. If these organisms are not observed, the patient is said to have NGU. The presence of extracellular organisms having the same morphology has no diagnostic significance. The complete absence of PMNs argues against urethritis. This test is more than 95 percent accurate in men with symptomatic acute urethritis.

The diagnosis of gonorrhea from the gram stain  is usually confirmed by the culture. The growth of typical colonies that are oxidase positive and consist of gram-negative diplococci strongly suggests gonorrhea. However, a negative culture in the face of a positive gram stain does not rule out GCU.

In contrast, the diagnosis of NGU requires the presence of urethritis in addition to an exclusion of urethral infection due to N. gonorrhoea. Chlamydia trachomatis causes 30 to 50 percent of cases of NGU in young adults. It is an obligate intracellular parasite that can only be grown in specialized tissue cells, not in routine culture medium. Coinfection with C. trachomatis and N. gonorrhoea is very common, occurring in 10 to 35 percent of men and in 40 to 60 percent of women, and has an effect on management strategies.

There are many options in the treatment of gonococcal urethritis. A single dose of ceftriaxone (250 mg IM) will still reliably eradicate N. gonorrhoea from patients with uncomplicated infection. The 1 mL injection of ceftriaxone is less painful if reconstituted with 1% xylocaine.

Persistence or recurrence of urethritis within 6 weeks of therapy occurs more commonly when NGU is not due to Chlamydia. The persistence of urethritis should be documented by observing PMNs on a urethral smear or urinalysis. Reinfection is the most common cause of recurrence. A careful sexual history regarding reexposure and adequate treatment of sexual partners is critical to the management of this condition. Careful evaluation for untreated sexual partners is essential. Once treatment failures, non-compliance, and re-exposure have been ruled out, a wet prep from the urethra should be examined for T. Vaginalis. Treatment should be with Metronidazole 2 grams orally once plus Erythromycin 500mg base or 800 mg EES orally QID for 7 days.

The absence of PMNs suggests resolution of the infectious process but with a persistent pain syndrome that does not require further treatment with antimicrobials. Generally, 15 to 30 percent of all persistent urethritis or dysuria is noninfectious and resolves within 6 months without therapy. Also, in this situation consider Herpes Simplex virus as a source.