What’s in a Wet Prep?

We have been doing wet preps a plenty in resident clinic lately, and I find myself reviewing the same info.  That’s sounds like a good reason for a blog post!  I’ve organized by diagnosis below, with history, PE, and wet prep clinical pearls.

Bacterial Vaginosis (40-45% of vagnitis)

  • HX: profuse discharge, thin, watery. Worse after menses or after intercourse.  May be foul-smelling. Usually not painful, pruritic.
  • PE: Cup of milk


  • Wet Prep: Clue cells.  Which is one of those things that is easy to say, but hard to describe.  Here’s a picture of normal squamous epithelial cells, followed by clue cells.

Cell borders are smooth, cytoplasm is clear, except for the nucleus.

Clue Cells

Cells look “dirty”- cytoplasm is not so clear and the borders are irregular. In reality, the cytoplasm is the same, but bacteria are all around the outside of the cell. 

Candidiasis (20-25%)

  • HX: Thick, white, clumpy, “cottage cheese” discharge, but may be thin and watery. Pruritus, irritation, vaginal soreness
  • PE: White adherent discharge. Really don’t need the wet prep to diagnose this. candidiasis
  • Wet Prep: This is where the KOH prep is helpful.  KOH breaks down the normal squamous cell walls, so hyphae are left.hyphae

Trichomonas (15-20%)

  • HX:  Kind of a mix between the above two. Lots of discharge, foul-smelling, thin (like BV), but pain, pruritus, dysuria (like Candida).
  • PE: Strawberry cervix is the board question, but it is rare. More often you see the discharge (it’s thin and yellowish), and the cervical mucosa is red, friable.
  • Wet Prep:  Trichomonads.  Best way to see these is to look at the edges of the sample, and just leave the slide in one place for a while.  Trich cells are more round/oval and smaller than the irregular shaped squamous cells.  If you are patient, you can often see something moving – might just be the flagella moving, or you might notice the whole cell slowly moving against the flow of the rest of the liquid on the slide.


Cervicitis (GC, Chlamydia)

  • HX: discharge is similar to Trichomonas, thin and watery but with associated symptoms of pain/pruritus/dysuria.  If systemic sx: nausea, fever, abdominal pain- think PID.
  • PE: friable, irritated cervix.  Cervical motion tenderness  or uterine tenderness on bimanual exam.
  • Wet Prep: Normal looking squamous cells, may see lots of white cells (smaller, less clear cytoplasm) in the background.

If you are more of a table person, here’s most of the info above in handy chart form.

Disease History Wet Prep Pearls
Bacterial Vaginosis Profuse Discharge, not painful/pruritic Clue Cells Women live with this for months before presenting.  Worse after menses, intercourse
Candidiasis Thick, white adherent discharge Normal cells, but use KOH to identify Hyphae If you see this, can skip the wet prep
Trichomonas Combo of above- thin watery discharge, also painful/pruritic Normal, but with white cells/trichomonads Foul smelling discharge (even without the KOH)
Cervicitis Similar to Trich, friable and painful cervix Lots of white cells May be GC, Chlamydia, Trich, HSV, others. (always  test for other STIs)

Did you know that we have a dropbox for pocket cards? This is so that you can keep them all in your pocket (on your phone). I’ll put the chart below there. If you want a link to the dropbox, send me an email or comment below and I’ll hook you up.  Another benefit to reading I Hate Rashes!


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.