• Differential diagnosis of vaginosis/vaginitis

• Guide selection of appropriate therapy

• Screen for bacterial vaginosis in selected cases

Vaginal symptoms such as abnormal discharge, unpleasant odor, itching, and burning are common reasons for gynecologic consultation and typically lead to a diagnosis of bacterial vaginosis (BV), parasitic vaginitis (vaginal trichomoniasis; VT), or yeast vaginitis (vaginal candidiasis; VC).

BV is the most common finding in women with vaginal symptoms, affecting 22% to 50% of symptomatic women.¹ Although not sexually transmitted, it often occurs as a coinfection with a sexually transmitted infection (STI). BV is characterized by replacement of normal Lactobacillus flora with anaerobic and other bacteria. For example, an abnormally high level of Gardnerella vaginalis, a part of the normal flora, is a marker of BV. Because BV is a risk factor for development of vaginal cuff cellulitis, pelvic inflammatory disease, and endometritis following gynecologic surgery, the Centers for Disease Control and Prevention (CDC) suggests screening and treatment of BV prior to such surgery.²

VT is an STI caused by Trichomonas vaginalis and it is estimated that 5 million women are infected each year in the United States.³ VT is diagnosed in 4% to 35% of women presenting with symptoms of vaginosis/vaginitis.¹ The majority of women with VT also have BV. Moreover, VT has been associated with increased risk of acquiring human immunodeficiency virus (HIV).

BV and VT are both associated with adverse pregnancy outcomes, including premature rupture of the membranes, preterm labor and delivery, and low birth weight. The CDC, therefore, has recommended BV and VT detection and treatment in symptomatic women.² Furthermore, detection and treatment of BV, but not VT, is recommended in asymptomatic pregnant women who have a history of premature delivery. VT treatment has not been shown to benefit pregnancy outcome in asymptomatic women.

VC is present in 17% to 39% of symptomatic women.¹ About 75% of women develop VC at some point during their lifetime and approximately 45% will suffer from a second occurrence; 5% have recurrent candidiasis, which is frequently intractable.² Although C albicans accounts for 80% to 90% of such infections, VC has also been associated with C glabrata, C parapsilosis, and C tropicalis and, rarely, with C kefir, C krusei, C pseudotropicalis, C lusitaniae, and C rugosa.⁴

Identifying the cause of vaginosis/vaginitis is essential for selection of pathogen-specific therapy. Clinicians have traditionally diagnosed vaginal infection using a combination of gynecologic examination, vaginal pH, microscopic evaluation of Gram stain and/or wet mount, and an amine odor test. Such procedures fail to support a diagnosis in approximately 30% of symptomatic patients and cannot detect mixed infections, which are common. Nucleic acid probe testing, which is more sensitive and specific than the office procedures mentioned above,⁵ avoids these limitations.

In this nucleic acid probe assay, specific DNA probes are hybridized to the ribosomal RNA of Candida species, G vaginalis, and T vaginalis. Each organism is detected with separate capture and color development probes. The analytical sensitivity is 1 x 10⁴ CFU/assay for Candida species, 2 x 10⁵ CFU/assay for G vaginalis, and 5 x 10³ trichomonads/assay for T vaginalis. Results are reported as detected or not detected for each organism.

The Candida species detected include C albicans, C glabrata, C kefir, C krusei, C parapsilosis, and  

C tropicalis.

CPT codes*: 87480, 87660, 87510

The sensitivity and specificity of this nucleic acid probe assay, relative to 2 reference methods (microscopy and culture), are listed in the Table. For cases in which probe results were positive and the reference method result was negative (ie, potential false-positive), alternative methods were used to reconcile the discrepancy.

In symptomatic patients, a “detected” result for Candida species and T vaginalis is diagnostic of VC and VT, respectively. Because G vaginalis is normally found in the vagina, a “detected” result, although suggestive, is not definitive proof of BV. Results should be interpreted in conjunction with other test results and clinical findings. Adjunct tests useful to support a diagnosis of BV include vaginal pH (>4.5 in 90% of BV), the presence of clue cells (ie, epithelial cells with adherent coccobacilli) in a vaginal discharge wet mount, and a positive amine odor test.

A “not detected” result suggests that the patient is not infected with the target organism(s), but could also be due to an organism concentration below the assay detection limit or to improper specimen collection and handling.

Test performance has not been evaluated in patients treated with antimicrobial therapy; therefore, the test should not be used to monitor treatment.

Vaginal swab in Affirm™′  VPIII Ambient Temperature Transport System (ATTS)

Prepare the ATTS:

• Open the seal on the outer pouch and remove all components.

• Tear open the foil pouch and remove the ATTS reagent dropper.

• Cautiously break the ampoule in the ATTS reagent dropper by firmly squeezing the center of the vial with finger and thumb being careful not to puncture the plastic.

• Label the sample collection tube (SCT) with the patient identification information. Include the date and time of collection.

• Dispense the reagent from the reagent dropper into the SCT.

Vaginal sample collection:

• Place the patient in position for a pelvic examination.

• Insert an unlubricated speculum (ie, without jelly or water) into the vagina to permit visualization of the posterior vaginal fornix.

• Remove the swab from the wrapper and swab the posterior vaginal fornix. Twist or roll the swab against the vaginal wall 2 or 3 times, ensuring the entire circumference of the swab has touched the vaginal wall. Swab the lateral vaginal wall while removing the swab.

• Immediately place the swab into the SCT containing the ATTS reagent.

Seal the SCT:

• With the swab touching the bottom of the SCT, break the pre-scored handle of the swab just above the top of the tube.

• Place the cap over the exposed end of the swab and firmly press the cap onto the tube. The cap will “snap” onto the tube when properly seated.

• Ship immediately at room temperature.

Separate swabs should be used for other tests (eg, culture or microscopic studies).