Wet Smear and KOH Preparation

CHAPTER 160 Wet Smear and KOH Preparation



Gary R. Newkirk


Abnormal vaginal discharge is a common complaint. In fact, vaginitis is the most common gynecologic diagnosis in primary care. Vulvovaginal candidiasis (VVC), bacterial vaginosis (BV), and trichomoniasis (trich) account for over 90% of abnormal vulvovaginal symptoms and discharge. Frequently, several pathogens may coexist. Office-based wet smear, potassium hydroxide (KOH) preparation, and vaginal secretion pH should be used to ensure a more accurate diagnosis and effective treatment of vaginitis. Empiric treatment for vulvovaginal symptoms including vaginal discharge should be avoided until appropriate testing is performed making a specific diagnosis.



Anatomy


Obtaining vaginal or vulvar samples to determine the cause of vulvovaginal symptoms and discharge requires familiarization with lower female genital anatomy and the basic skills of pelvic examination. Chapter 137, Colposcopic Examination, and Chapter 151, Pap Smear and Related Techniques for Cervical Cancer Screening, review the anatomy and basic steps of the pelvic examination.



Indications



• Abnormal vaginal discharge

• Vulvar or vaginal itching, burning, or pain

• Discomfort with intercourse


Contraindictions



• Active menses (clinician should not postpone evaluation for significant discharge or vulvovaginitis during menses)

• Recent douching (relative contraindication)

• Recent application of vaginal creams or lubricants (relative contraindication)


Equipment and Supplies



• Vaginal speculum

• Small cotton-tipped applicators

• Small test tubes

• Normal saline

• 10% potassium hydroxide solution

• Glass slides and coverslips

• pH test tape (narrow range needed: Micro Essential laboratory; pH paper on a stick: Imagyn Gynecology)

• Microscope


Precautions



• In some instances, women with extremely inflamed vulvovaginitis cannot tolerate speculum insertion. The clinician should be prepared to perform a limited examination by obtaining samples from the distal vagina or vulva.

• The clinician should maintain a high index of suspicion for a primary cervical infection with either Chlamydia trachomatis or Neisseria gonorrhoeae in patients at risk or for those who have an observed mucopurulent cervicitis.


Preprocedure Patient Preparation



• Discuss the need for pelvic (speculum) examination and testing requirements that may incur additional costs.

• Written consent is not required, although women should be informed if testing for gonorrhea or Chlamydia is performed.

• Educate women during annual pelvic examinations regarding avoidance of douching, creams, and lubricants prior to the evaluation of abnormal discharge.


Procedure



1 With the patient in the lithotomy position begin with careful examination of the vulva for inflammation, ulcers, lesions, and discharge.

2 Insert a warm lubricated speculum and expose the cervix.

3 Inspect the cervix, vaginal walls, and fornices. Perform cervical sampling for gonorrhea, Chlamydia, or herpes as deemed appropriate. Consult with your laboratory on the detection methodology (culture, DNA testing) and technique for sample collection, preparation, and transport.

4 Collect secretions from both the vaginal fornices and lateral vaginal walls by gently rubbing with a cotton-tipped applicator. Place the cotton-tipped applicator with sample in a patient identified small test tube that contains 1 mL of 0.9% (normal) saline. Leave the applicator in the test tube until the wet smear is performed in the laboratory. Remove the speculum from the vagina.

5 To properly prepare the slide for review, vigorously mix the swab in the saline solution. Remove the swab from the tube and depress it on the slide to express a small amount of fluid. Apply a coverslip over the sample. The slide (“wet prep” or “wet smear”) is then immediately examined with the microscope under low power (10×) for vaginal squamous cells, white blood cells, lactobacilli, clue cells, and trichomonads. Examine under low and high power (40×). If a KOH slide is needed, prepare another slide exactly as previously described. Before placing the coverslip, put one drop of a 10% KOH solution on the sample. Apply a coverslip. Allow to air- or flame-dry and examine under low power for hyphae, mycelial tangles, or spores. The “whiff test” is performed when KOH is applied to the sample (see later discussion).

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May 14, 2017 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Wet Smear and KOH Preparation

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