eMedicine Specialties > Urology > Common Problems of the Urethra

Urethritis: Differential Diagnoses & Workup

Author: Martha K Terris, MD, FACS, Professor, Department of Surgery, Medical College of Georgia
Coauthor(s): Kamran P Sajadi, MD, Staff Physician, Division of Urology, Medical College of Georgia Health System
Contributor Information and Disclosures

Updated: Aug 10, 2009

Differential Diagnoses

Other Problems to Be Considered

Trichomonal vaginitis
Candidal vaginitis
Alcohol ingestion
Contact dermatitis secondary to spermicides
Guilt over sexual behavior likely to be perceived as deviant
Guilt over infidelity
Dried semen mistaken for discharge
Stevens-Johnson syndrome
Foreign body
Fungal infections of the genitourinary tract

Workup

Laboratory Studies

Urethritis can be diagnosed based on the presence of one or more of the following: (1) a mucopurulent or purulent urethral discharge, (2) urethral smear that demonstrates at least 5 leukocytes per oil immersion field on microscopy, and (3) first-voided urine specimen that demonstrates leukocyte esterase on dipstick test or at least 10 white blood cells (WBCs) per high-power field on microscopy.

All patients with urethritis should be tested for N gonorrhoeae and C trachomatis.

• Gram stain
  • Traditionally, treatment was based on Gram stain results. Patients with gram-negative intracellular diplococci on urethral smear received treatment for gonococcal urethritis, and those without gram-negative intracellular diplococci received treatment for nongonococcal urethritis (NGU).
  • Because current recommendations suggest patients receive concomitant treatment for both, and with the success of nucleic acid amplification tests (NAATs), a Gram stain may be unnecessary.
• Urethral culture for N gonorrhoeae and C trachomatis
  • Endourethral culture (obtained by gently inserting a malleable cotton-tipped swab 1-2 cm into the urethra), rather than culture of the expressible discharge, is necessary to test for C trachomatis infection. Endocervical cultures should also be obtained in women.
  • This culture may be a useful screening tool for penicillinase-producing N gonorrhoeae or chromosomally mediated resistance to multiple antibiotics; however, the results do not influence the initial antibiotic therapy, and performing this screening may not be cost-effective.
• Urine
  • Urinalysis is not a useful test in patients with urethritis, except for helping exclude cystitis or pyelonephritis, which may be necessary in cases of dysuria without discharge. Patients with gonococcal urethritis may have leukocytes in a first-void urine specimen and fewer or none in a midstream specimen. More than 30% of patients with NGU do not have leukocytes in urine specimens.
  • Many nucleic acid–based tests for C trachomatis and N gonorrhoeae can be performed on urine specimens (see below). These require a first-voided specimen. For Chlamydia species, endourethral samples are more accurate.
• Nucleic acid amplification tests
  • Polymerase chain reaction assays are available for gonococcal urethritis and Chlamydia infection. NAATs are also available for Mycoplasma species, Ureaplasma species, and T vaginalis, but these are not recommended, as they are expensive and do not alter the choice of treatment.
  • NAATs are the preferred test for Chlamydia and are more sensitive than traditional culture methods. Chlamydia DNA probe results are 60%-70% sensitive and nearly 100% specific. Obtain samples on swabs at least 2 hours after micturition, using a calcium-alginate swab on a nonwooden stick inserted at least 1 cm in depth to help prevent false-negative findings. Chlamydia ligase chain reaction is 90%-95% sensitive and nearly 100% specific. Obtain samples on swabs at least 2 hours after micturition, using a calcium-alginate swab on a nonwooden stick inserted at least 1 cm in depth to help prevent false-negative results.
  • DNA-based tests, unlike culture, do not allow for antibiotic susceptibility testing, but this is unnecessary in most patients.
• Potassium hydroxide preparation: This is used to evaluate for fungal organisms.
• Wet preparation: Secretions reveal the movement of trichomonal organisms, if present.
• STD testing: Patients with urethritis should be counseled about the risk for more serious STDs. They should be offered syphilis serology (Venereal Disease Research Laboratory test or Rapid Plasma Reagin test) and HIV serology.
• Nasopharyngeal and/or rectal swabs: Men who have sex with men (and perhaps other patients) should undergo gonorrhea screening with nasopharyngeal and/or rectal swabs. Validation of NAATs for these specimens is still in progress.¹
• Pregnancy testing: Women who have had unprotected intercourse should be offered pregnancy testing.
• Other tests: Patients with reactive arthritis are diagnosed based on the presence of NGU and clinical findings of uveitis and arthritis. HLA-B27 testing is of limited value. More readily available laboratory findings, such as elevated erythrocyte sedimentation rate (ESR) in the absence of rheumatoid factor, may be helpful.

Imaging Studies

• Imaging studies, specifically retrograde urethrography, are unnecessary in patients with urethritis, except in cases of trauma or possible foreign body insertion.

Procedures

• Catheterization
  • In cases of urethral trauma, urethral catheter placement can hold the urethra open to avoid urinary retention caused by edema or a flap of elevated mucosa.
  • The catheter also serves to tamponade urethral bleeding.
• Cystoscopy
  • When urethral catheter placement is not possible after urethral trauma, careful negotiation of the urethra with a flexible cystocope can allow passage of a guidewire, over which the Council tip urethral catheter can be placed. This can generally be performed in the emergency department or outpatient clinic with local anesthesia (lidocaine jelly). However, if not easily accomplished on the initial attempt, this procedure should be aborted to avoid further urethral trauma, and a suprapubic tube should be placed.
  • A foreign body or stone in the urethra, which may mimic urethritis, can be removed cystoscopically. Unless the object is very small and very distal, this procedure probably should be undertaken in the operating suite while the patient is under anesthesia. A rigid cystoscope with a larger lumen sheath and working port allows utilization of more secure endoscopic graspers. The object can often be removed through the large lumen of the cystoscope sheath, rather than pulling it through the distal urethra (which may cause further trauma).
• Filiforms and followers: Filiforms and followers can also be used by experienced urologists but are being used less frequently in cases of urethral trauma because of the wide availability of flexible cystoscopes. In addition, this technique can lead to more severe urethral trauma if not used correctly.
• Suprapubic tube placement: With more severe urethral trauma preventing urethral catheter placement or inadequate facilities for emergent cystoscopy in patients with urethral obstruction due to trauma or foreign bodies, a suprapubic catheter is an excellent temporizing measure to divert urine and relieve patient discomfort until definitive therapy can be undertaken.

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