Table 37.

Laboratory Diagnosis of Genital Lesions

Etiologic Agents	Diagnostic Procedures	Optimum Specimen	Transport Issues and Optimal Transport Time
HSV-1 and HSV-2	NAATb	Scraping or aspirate	Assay-specific; consult laboratory
In children with genital lesions, consider atypical VZVa	DFA	Scraping of lesion base rolled directly onto slidea	RT
	Culture (rarely performed)	Scraping of lesion base and placed in VTM//UTMc	RT, If >2 h, refrigerated
	Serologyd	Serum	Clot tube, RT
HPV-16/18 genotyping Refer to guidelines for specific age, cytology, and triaging recommendations	DNA hybridization probe or NAAT for high-risk HPV types onlye	Endocervical brush into liquid cytology medium or transport tube	RT, 48 h
Genital wartsf	Histopathology; high-risk HPV testing not done on warts	Biopsy or scraping	Formalin container, RT, 2–24 h
Syphilis	Darkfield microscopyg Test is not widely available and specimen must be transported to laboratory immediately to visualize motile spirochetes	Cleanse lesion with gauze and sterile saline Swab of lesion base directly to slide	RT, immediately to laboratory
	DFA–Treponema pallidumh,i	Cleanse lesion with gauze and saline Swab of lesion base directly to slide. Clarify source, genital, oral, rectal	Slide should be dry before placing in holder and/or transporting to laboratory
	Serology Nontreponemal (VDRL or RPR)j	Serum	Clot tube, RT, 2 h
	Treponemal serology EIA/CIA or TPPA, FTA-ABS)k,l	Serum	Clot tube, RT, 2 h
Chancroid (Haemophilus ducreyi)m	Gram stain and culturen	Swab of lesion base without surface genital skin	RT immediately to laboratory
	NAATb
Lymphogranuloma venereumm (Chlamydia serovars L1, L2, L2a, L2b, L3)	Cell cultureo	Swab of ulcer base, bubo drainage, rectum	RT, immediately to laboratory
	Serology MIFp	Serum	RT, 2 h
	Serology Complement fixationq	Serum	RT, 2 h
	NAATr	Swab of ulcer base, bubo drainage, rectum	RT, 2 days; or refrigerate
Granuloma inguinalem (donovanosis) Klebsiella granulomatis	Giemsa or Wright stain in pathology. Visualization of blue rods with prominent polar granules	Scraping of lesion base into formalin	RT, 2 h
Scabies	Microscopic visualization	Collect parasite from skin scrapings using sterile scalpel blade with a drop of mineral oil to facilitate adherence of the organisms	RT, within 1 h
Lice	Macroscopic visualization	Hair should be submitted in a clean container	RT, 1 h

Abbreviations: CIA, chemiluminescence immunoassay; DFA, direct fluorescent antibody; EIA, enzyme immunoassay; FTA-ABS, fluorescent treponemal antibody–absorbed; HPV, human papillomavirus; HSV, herpes simplex virus; MIF, microimmunofluorescent stain; NAAT, nucleic acid amplification test; RPR, rapid plasma reagin; RT, room temperature; TPPA, Treponema pallidum particle agglutination assay; UTM, universal transport medium; VDRL, Venereal Disease Research Laboratory; VTM, viral transport medium; VZV, varicella zoster virus.

^aEpithelial cells are required for adequate examination and used to assess quality of the specimen collection; consider atypical VZV in children with genital lesions using DFA. Typical 3-well slide allows distinction between HSV-1, HSV-2, and VZV.

^bSeveral NAATs are US Food and Drug Administration (FDA)–cleared. Specimen source and test availability are laboratory specific. Provider needs to check with laboratory for allowable specimen source and turnaround time. More sensitive than culture and DFA, especially when lesions are past vesicular stage.

^cCheck with laboratory; most are maintained and shipped at RT, ice not required.

^dSerology can be non-specific for HSV-1 and HSV-2 differentiation; should be limited to patients with clinical presentation consistent with HSV but with negative cultures by NAAT; request type-specific glycoprotein G–based assays that differentiate HSV-1 and HSV-2.

^eHigh-risk HPV testing currently recommended in women ≥30 years of age. HPV testing is not recommended for the diagnosis of HPV in a sexual partner or in patients aged ≤21 years (adolescents); options for women aged 21–29 years vary depending on cytology, HPV-16/18 genotyping in cytology negative and high-risk HPV positivity helps with triage.

^fThe diagnosis of genital warts is most commonly made by visual inspection; high-risk HPV testing is not recommended.

^gDarkfield microscopy not widely available.

^hLimited availability typically performed in public health laboratories.

ⁱViable organisms are not required for optimal test performance; clarify source (genital, oral, rectal) because nonpathogenic treponemes can be detected in nongenital sites.

^jNontreponemal tests (RPR and VDRL) are less sensitive in early and late disease, and become negative after treatment; do not use to test pregnant patients due to potential for false-positive results.

^kTreponemal tests: EIA or CIA formats, TPPA, and FTA-ABS; monitor titers using same type of test and/or same laboratory; positive for life; human immunodeficiency virus (HIV)–infected patients may have unusual serologic responses.

^lTreponemal test may be performed first with subsequent testing done with nontreponemal tests such as RPR (reverse testing algorithm). Confirmation with a second treponemal test different than the first is required in positive EIA/CIA but negative RPR tests. For laboratories that routinely perform the reverse algorithm, a special request for testing by RPR may be required when following positive syphilis patients for treatment effectiveness.

^mUncommon genital ulcers in the United States are typically diagnosed by clinical presentation, risk factors, and exclusion of syphilis and HSV; HIV testing should be part of workup.

ⁿGram stain with chancroid organisms shows small rods or chains in parallel rows, “school of fish”; culture requires special media and sensitivity is only 30%–70%. Testing should only be performed by laboratory that regularly performs this testing.

^oCell culture sensitivity about 30%; rectal ulcers in men who have sex with men.

^pMIF titers ≥256 with appropriate clinical presentation suggests lymphogranuloma venereum (LGV).

^qComplement fixation titers ≥64 with appropriate clinical presentation suggests LGV, sensitivity 80% at 2 weeks.

^rNAATs for C. trachomatis (CT) will detect L1–L3 but do not distinguish these from the other CT serovars; typical lesion sites not FDA-cleared; some laboratories have validated rectal swabs; NAAT performed through the Centers for Disease Control and Prevention in outbreak situations [210].

^sPlace a drop of mineral oil on a sterile scalpel blade. Allow some of the oil to flow onto the papule. Scrape vigorously 6 or 7 times to remove the top of the papule. (Tiny flecks of blood should be seen in the oil.) Use the flat side of the scalpel to add pressure to the side of the papule to push the mite out of the burrow. Transfer the oil and scrapings onto a glass slide (an applicator stick can be used). Do not use a swab, which will absorb the material and not release it onto the slide. For best results, scrape 20 papules.