Fern Test - Amniotic Fluid Crystallization Test     
MCL Procedure for Waived Applications
         effective 8/17/02

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Specimen:  Vaginal swab obtained from the posterior vaginal pool.
- avoid the use of any lubricants or antiseptics
- use a sterile swab and do not touch the mucus plug
- prepare a thin smear on a glass microscope slide by spreading evenly.

Testing: 

fern_image 1.jpg (68521 bytes) fern_image2.jpg (64154 bytes)
Positive Fern Test- note crystal formations Negative Fern test- no "fern-like" cytstals

Interfering Substances/ limitations:
If present, blood, urine or cervical mucus can result in a false positive finding.
False negative findings can result from prolonged rupture of membranes (>24 hr).

 Quality control:

Images courtesy of University of Texas Medical Branch- POCT team. Used with permission.