Resident Editor: Nadine Pardee, M.D.

Faculty Editor: Alison Huang, M.D. Miranda Dunlop, M.D.

Indications

• Any female complaining of lower abdominal/pelvic pain, vaginal irritation, and/or abnormal vaginal discharge.
• Despite the advent of newer DNA and antigen testing with similar sensitivity and specificity, wet mount in conjunction with clinical exam remains the diagnostic gold standard for vaginitis. Cost-effectiveness has not been studied.

Contraindications

• None; however, if you suspect sexual assault, refer to an ED since there are special techniques to collect forensic samples for evidence.

Materials needed

• Saline, KOH, glass slide, cover slips, pH paper (use pH on UA strip), cotton-tipped swab, and a microscope. You may wish to perform GC/CT testing with a NAAT swab if doing a cervical swab
• You do not need a speculum exam to perform a wet mount, however may need to examine the cervix for other reasons based on the patient’s complaints.

Technique

• Obtain sample of vaginal discharge during the pelvic examination by touching  a dry cotton-tipped swab to the vaginal wall . Note: do not contaminate the swab with water, lubricant or cervical mucus since these will all change the pH reading.
• Roll the swab onto pH paper to moisten and determine the pH.
• For saline prep: Apply sample to glass slide and add 1-2 drops of normal saline, cover with cover slip, and examine with microscope under low and high power. Look for mobile trichomonads and clue cells (vaginal epithelial cells covered with bacteria.)
• For KOH prep: Apply sample to glass slide and add 1 drop of 10% KOH. Immediately perform whiff test to check for amine odor (fishy smell), then cover slide with  a cover slip. The KOH breaks down the  cellular elements to allow you to look for for hyphae and budding yeast under the microscope 

Findings

• Examine the saline prep first because trichomonads will die with time, and KOH requires time to digest cellular elements.
• Normal: Numerous epithelial squamous cells, rare PMNs. .
• Candidiasis: Pseudohyphae with KOH preparation or budding yeast if nonalbicans candida
  • https://www.aafp.org/afp/2018/0301/hi-res/afp20180301p321-f2.jpg
• For pH greater than 4.5 in premenopausal women, consider bacterial vaginosis or trichomoniasis infection if appropriate symptoms and findings:
• Trichomonas: Numerous PMNs, motile trichomonads with saline prep.
  • https://www.aafp.org/afp/2018/0301/hi-res/afp20180301p321-f3.jpg
• Bacterial vaginosis (BV): Amsel criteria have a 90% likelihood for BV -- ¾ of: 1) positive amine whiff test with KOH prep, 2)pH >4.5 in a premenopausal woman 3) homogenous, thin white or grey vaginal discharge, 4) Presence of clue cells (bacteria-studded squamous epithelial cells, best appreciated at the edge of the cell) on saline prep.
  • https://www.aafp.org/afp/2018/0301/hi-res/afp20180301p321-f1.jpg
  • https://www.uptodate.com/contents/image?imageKey=OBGYN%2F52425&topicKey=OBGYN%2F5477&search=vaginitis&rank=1~150&source=see_link
• See Vaginitis Chapter for more details

References

Birnbaumer DM. Chapter 25. Microscopic Findings. In: Knoop KJ, Stack LB, Storrow AB, Thurman RJ, eds. The Atlas of Emergency Medicine. 3rd ed. New York: McGraw-Hill; 2010.

http://www.accessmedicine.com/content.aspx?aID=6008795. Accessed April 30, 2013.

Edelman A, Anderson J, Lai S, Branner DAV, and Tegtmeyer K. Videos in Clinical Medicine: Pelvic Examination. NEJM 2007; 356:e26

Lowe NK, Neal JL, Ryan-Wegner RA. Accuracy of the Clinical Diagnosis of Vaginitis Compared to a DNA Probe Laboratory Standard. Obst Gynecol 2009 Jan; 113(1): 89-95

Paladine HL. Vaginitis: Diagnosis and Treatment. Am Fam Physician 2018 Mar 1; 97(5)321-329)

American College of Physicians. Wet Mount Examinations. Reprint from Focus On, 1998, Issue 3. http://www.acponline.org/running_practice/mle/wm_exams.htm. Accessed April 30, 2013.