What initial workup and tests should be requested for a patient presenting with yellow vaginal discharge?

Initial Workup for Yellow Vaginal Discharge

Order a vaginal swab for NAAT testing of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis, combined with immediate point-of-care wet prep microscopy and vaginal pH testing. 1

Point-of-Care Testing (Immediate)

Perform these tests during the clinical encounter:

• Vaginal pH measurement: Use pH paper dipped in vaginal secretions from the speculum tip, reading within 10 seconds. pH <4.5 suggests candidiasis, while pH >4.5 indicates bacterial vaginosis or trichomoniasis. 2, 1

• Saline wet mount: Place vaginal secretions in 0.5-1 mL saline on a microscope slide and examine immediately for clue cells (bacterial vaginosis), motile trichomonads (trichomoniasis), and white blood cells. This must be examined within 30 minutes to 2 hours, as motile organisms lose viability beyond this window. 2, 1

• 10% KOH preparation: Mix vaginal secretions with KOH to visualize pseudohyphae and budding yeast for candidiasis, and perform the whiff test—a positive "fishy" odor indicates bacterial vaginosis. 2, 1

Laboratory Testing (Send Out)

Order these tests simultaneously with point-of-care testing:

• NAAT panel for CT/GC/TV: This is mandatory because wet mount microscopy has poor sensitivity (40-80% for Trichomonas, 40-70% for yeast) compared to NAAT. Trichomonas prevalence equals or exceeds CT/GC in many populations, making simultaneous screening essential. 2, 1

• Quantitative Gram stain (Nugent criteria): This is the most specific test for bacterial vaginosis diagnosis, though wet prep with Amsel criteria is sufficient for routine clinical diagnosis. 2, 1

• Vaginal culture: Order this only for recurrent or persistent yeast infections to identify non-albicans Candida species requiring different treatment. 1

Specimen Collection Technique

• Collect vaginal swabs from pooled vaginal discharge or lateral vaginal walls using a cotton swab during speculum examination. 2, 1

• Avoid contaminating the swab with cervical mucus, as this affects test accuracy. 1

• Place swabs in laboratory-provided transport medium—specimens remain stable at room temperature for 2 days for standard NAAT panels (CT/GC/TV) and up to 7 days for specific DNA probe tests. 2, 3

Physical Examination Findings to Document

During speculum examination, note:

• Cervical friability and hyperemia 1
• White plaques on the cervix 1
• Red punctate lesions (strawberry cervix) suggesting trichomoniasis 1
• Character of discharge (thin, homogeneous, thick, cottage cheese-like) 2

Critical Pitfalls to Avoid

• Never rely solely on wet mount for Trichomonas diagnosis—its sensitivity is only 40-80% and requires examination within 30 minutes to 2 hours while organisms remain motile. 3

• Don't assume normal pH excludes all infections—yeast typically has pH <4.5, while bacterial vaginosis and trichomoniasis have pH >4.5. 3

• Don't delay wet mount examination beyond 2 hours—organisms lose motility and become undetectable after this window. 3

• Don't use wet mount/KOH alone for bacterial vaginosis diagnosis—wide variation in sensitivity exists, and consistent microscopic interpretation is difficult for many laboratories. 3

Cost-Effectiveness Consideration

A comprehensive, pH-guided testing strategy at the initial visit (performing yeast culture, GC/CT probes immediately, and Gram stain/Trichomonas culture only when pH exceeds 4.9) is both less expensive and more effective than sequential testing, reducing symptom duration by up to 1.3 days. 4