Vaginitis Workup

The workup for patients with vaginitis depends on the risk factors for infection and the age of the patient. All women presenting with abnormal vaginal discharge should have a careful pelvic examination. Condition-specific tests (ie, colposcopy and cervical biopsies) are indicated for suspected cervical cancer.

Studies that may be performed in cases of suspected vaginitis include saline wet mount, the so-called whiff test, pH testing, culture, nucleic acid amplification testing, and a number of other second-line tests.

In a saline wet mount test, a drop of vaginal discharge is placed on a slide with 1-2 drops of 0.9% isotonic sodium chloride solution and examined under high power (×400).

This test is 60% sensitive and 98% specific for bacterial vaginosis. Clue cells are vaginal epithelial cells covered with many vaginal rods and cocci bacteria, creating a stippled or granular appearance. A decreased number of lactobacilli are observed, and white blood cells (WBCs) are absent.

In patients with vaginal candidiasis, the test reveals hyphae and budding yeast forms. In symptomatic women with trichomoniasis, saline wet mount is 80-90% sensitive for T vaginalis infection. Large numbers of WBCs (>10 per high power field [hpf]) and epithelial cells are observed.

In the whiff test, vaginal discharge is placed on a slide with 10% potassium hydroxide (KOH) solution. A positive test result is the release of an amine (fishy) odor after the addition of KOH to the discharge. The odor is due to the release of amines such as putrescine, cadaverine, histamine, and trimethylamine.

Bacterial vaginosis is associated with an intense amine odor on this test; however, the whiff test is not highly sensitive or specific for diagnosing this condition. A negative whiff test result is 65%-85% sensitive for candidal infection; as many as 30% of symptomatic candidiasis cases show false-negative results. The whiff test may be positive with Trichomonas vaginitis.

Vaginal pH can be determined with litmus paper. A pH greater than 4.5 is often found in patients with Trichomonas infection or bacterial vaginosis (84-97% sensitivity, 57-78% specificity). Recent intercourse, douching, cervical mucus, and blood can lead to false-positive results.

• Bacterial vaginosis - pH is 5.0-6.0

• Vaginal candidiasis - pH is less than 4.5

• T vaginalis infection - pH is 5.0-7.0

Cultures are of little use in diagnosing bacterial vaginosis and therefore are not generally indicated or recommended in this setting. Cultures with Nickerson or Sabouraud mediums should be performed in refractory or recurrent cases of vaginal candidiasis. Culture using Diamond medium or Trichosel broth is recommended for detection of trichomonads and should be used when infection is suspected but cannot be confirmed by other means. InPouch TV is 90-95% specific and 100% sensitive for culturing T vaginalis.

Gonorrhea usually causes a cervicitis, not a vaginitis, and may be asymptomatic. Symptomatic Neisseria gonorrhoeae infection usually results in a purulent discharge. Obtain cultures of the vagina (in prepubertal patients), cervix (in pubertal and adult patients), oral pharynx, and rectum if gonococcal vulvovaginitis is suspected. Obtain cultures by using a cotton-tipped swab and Thayer-Martin media on chocolate agar, incubated in a carbon dioxide–rich environment (see Pediatrics, Child Sexual Abuse).

Test for chlamydial vulvovaginitis via culture in prepubertal girls and in patients who show signs of abuse or sexual assault. Obtain rectal Chlamydia swabs (see Pediatrics, Child Sexual Abuse).

The use of nucleic acid amplification tests (NAATs) has been implemented in many office and emergency settings. Tests such as polymerase chain reaction (PCR) can be performed by using swabs of the cervix or vagina or by collecting a urine sample. NAATs may be performed as a screen in pubertal and adult women. They may also be used for initial screening in prepubertal children, but in view of medicolegal concerns, confirmation testing should be ensured. ^[8]

DNA amplification assays of genital tract specimens are both sensitive and specific. First-void urine specimens for NAATs have also been shown to be sensitive and specific in females. They are less invasive than swabs, and with confirmation (eg, repeat testing with a different NAAT), urine NAATs may be used for the evaluation of chlamydial infection and gonorrhea in cases of suspected sexual abuse.

Although NAATs are generally performed to test for these common sexually transmitted diseases, their utilization for the diagnosis of bacterial vaginosis has also been studied, and they have been shown to be potentially more sensitive and specific than Gram staining and clinical diagnosis. ^{[8, 9]}

The Affirm DNA hybridization method is 80% sensitive for Trichomonas and 94% sensitive for bacterial vaginosis. Oligonucleotide probes detect high (> 10⁷/mL) concentrations of Gardnerella vaginalis and can also can detect Candida. Antigen-detecting immunoassays, the Trichomonas Rapid Test (an enzyme-linked immunosorbent assay [ELISA] strip test with 80% sensitivity), DNA probes, and PCR are useful for detecting trichomonads.

Gram stain is 89-97% sensitive and 79-85% specific for detecting bacterial vaginosis. On Gram stain, clue cells are identified as epithelial cells covered by small gram-negative rods.

Gram stain or culture on Nickerson media and Sabouraud agar may enhance diagnosis of vaginal candidiasis. The Papanicolaou test (Pap smear) may have frequent false-positive results for yeast.

The Papanicolaou test is not accurate in the diagnosis of Trichomonas infections: Pap smears may reveal trichomonads but have high false-positive and false-negative rates. T vaginalis may be identified with Giemsa staining of in vitro culture specimens (see the image below).

(A) Two trophozoites of Trichomonas vaginalis obtained from in vitro culture, stained with Giemsa. (B) Trophozoite of T vaginalis in vaginal smear, stained with Giemsa. Images courtesy of Centers for Disease Control and Prevention.

The latex agglutination test employs polyclonal antibodies reactive against multiple species of Candida.

Gas-liquid chromatography can be used to detect the succinate-to-lactate ratio in vaginal fluid to assist in the diagnosis of bacterial vaginosis. Succinate and lactate are metabolites produced by anaerobic gram-negative rods and lactobacilli, respectively.

A cross-sectional study that involved 1,740 patients with vaginitis symptoms by Gaydos et al reported that a vaginal swab molecular-based test collected by patients by themselves or by clinicians can accurately diagnose most common bacterial, fungal, and protozoan causes of vaginitis. The vaginal swab test sensitivity for bacterial vaginosis was 90.5% (95% confidence interval [CI] 88.3-92.2%) and specificity was 85.8% (95% CI 83.0-88.3%). For Candida, the test sensitivity was 90.9% (95% CI 88.1-93.1%) and specificity was 94.1% (95% CI 92.6-95.4%) and test sensitivity was 93.1% (95% CI 87.4-96.3%) and specificity was 99.3% (95% CI 98.7-99.6%) for trichomoniasis. ^[10]

T vaginalis infection can be confused with koilocytotic atypia, caused by the human papillomavirus, and may mimic findings of mild dysplasia.

Bacterial vaginosis may produce inflammation and atypical squamous cells of undetermined significance (ASCUS) on Papanicolaou tests. In addition, bacterial vaginosis may be linked with cervical intraepithelial neoplasia (CIN).