FERN TEST

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FERN TEST
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Rupture of membranes

• 1- Patient history
• 2- Vaginal fluid with PH of 7.0 or greater
• 3- Positive fern test

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Fern test is based on

• The ability of amniotic fluid to form
• a fern pattern when air-dried on a
• glass slide

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False positive

• 1- Collection of cervical mucus (ferns in a
  coarse pattern)
• 2- Heavy contamination with blood(atypical,
  skeletonized )
• 3- Contamination with urine
• 4- Fingerprinted ( dirty) slides
• 5- Detergent contaminated slides, pipettes
• 6- Slide is dried under a circulating air current
• 7- Cytologic fixatives or preservatives are used

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False negative results

• 1- Slide is examined before it is completely
• dried
• 2- Prolonged rupture of membranes
• (gt 24 hrs )
• 3- When a small volume has leaked

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Fern test should be performed in conjunction with
theNitrazine test
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Reference range

• Amniotic fluid has a PH of
• 7.0 7.5

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• Positive fern positive Nitr. ROM
• Positive fern negative Nitr. ROM
• Negative fern positive Nitr. Repeat the
• test on another specimen
• Negative fern negative Nitr. No amniotic fluid