MaineMedicalCenter January 2008
Portland, Maine
FERNING TEST FOR THE DETECTION OF AMNIOTIC FLUID
PROVIDER-PERFORMED MICROSCOPY
INTENDED USE:
The Ferning Test, used in conjunction with the Nitrazine Test, detects the leakage of amniotic fluid from the membranes surrounding the fetus during pregnancy. The test is a provider-performed micro-scopic procedure (PPMP), and only formally trained personnel are authorized to perform the test.
PRINCIPLE:
Fern-like crystals form when a thin smear of amniotic fluid is allowed to air dry. This phenomenon is in part due to the fluid’s protein and sodium chloride content. A positive test shows the presence of fern-like patterns characteristic of amniotic fluid crystals.
PATIENT PREPARATION:
1.Identify the patient.
2.Explain the procedure to the patient.
SPECIMEN:
If the specimen is to be tested away from the patient's bedside, the specimen container must be labeled with the patient's full name before leaving the bedside.
A vaginal swab obtained from the posterior vaginal pool is required.Use a sterile swab and do nottouch the mucus plug. Avoid the use of any lubricants or antiseptics.Prepare a thin smear on a glass microscope slide by spreading evenly.Allow the slide to air dry. Do not apply heat and do not coverslip the slide.
MATERIALS:
PROM (Premature Rupture of the Membranes) Kit is assembled in Labor & Delivery.
COMPONENTS: Each PROM Kit is packaged in a self-sealed bag and is labeled with the NitraTest expiration date, the NitraTest lot number, the initials of the individual assembling the kit, and the date assembled. Each PROM Kit contains the following:
One 6- to 8-inch piece of NitraTest Paper
One cotton-tipped swab
One CultureSwab™ Collection and Transport System (liquid Stuart transport medium)
One frosted-end, glass microscope slide hand-wrapped with gauze
PREPARATION: The PROM Kit is ready to use as supplied.
STORAGE AND STABILITY: The kit is stored at room temperature (under 86°F) away from direct light. The contents are stable until the expiration date printed on the product label. Do not use the kit beyond the expiration date printed on the label.
EVIDENCE OF DETERIORATION: Color variation of the paper from tan to olive green will not interfere with accurate pH readings.
QUALITY CONTROL:
Examine the NitraTest Paper for signs of deterioration before use, and do not use the PROM Kitbeyond the expiration date. Since commercially-prepared quality control materials are not readily available for this test, strict adherence to the technique described in this procedure is imperative.
The microscope and lens must be kept clean at all times to facilitate the examination of the preparation. Professional microscope cleaning and maintenance services are readily available.
PROCEDURE FOR TESTING PATIENTS:
(1) Examine the fully-dried slide microscopically, using the 10X objective and reduced light.
(2)Observe for "fern-like" crystals. The presence of crystals indicates that the fluid is amniotic fluid.
(3)Record the results. Write your name, the date, time and findings on the patient record.
FERN LIKE CRYSTALS:
INTERPRETATION OF RESULTS AND REPORTING FORMAT:
The presence of "fern-like" crystals indicates that the fluid is amniotic fluid; report as a POSITIVE FERNING TEST.
The absence of "fern-like" crystals indicates that the fluid is not amniotic fluid;report as a NEGATIVE FERNING TEST.
Positive Ferning Test - note crystal formations / Negative Fern test - no "fern-like" crystalsINTERFERENCES AND LIMITATIONS:
1.False-positive results may occur from specimens contaminatedwithblood, urine or cervical mucus.
2.False-negative results can be produced by prolonged rupture of membranes (longer than 24 hours).
REFERENCES:
College of American Pathologist Surveys Program, Northfield, Illinois, 2010.
Creasy, Robert K. and Resnik, Robert: Maternal-Fetal Medicine (4th ed.), WB Saunders Company, Philadelphia, 1999, pp. 647-8.
OBTAINING TECHNICAL ASSISTANCE:
Denis Netto, Technical Consultant 662-4997
SIGNATURES:
Authorized signatures, as well as periodic review records, are on file with the Maine Medical Center POCT Program Technical Consultant.
REVIEW SCHEDULE:
PREPARED BY: / Denis R. Netto, MT(ASCP)Technical Consultant / January 28, 2008
Revised August 12, 2010
SUPERSEDES: / Ferning Test
for the
Detection of Amniotic Fluid / January 28, 2008
ADOPTED BY: / Timothy E. Hayes, DVM, MD
POCT Program Director / August 12, 2010
ADOPTED BY: / Michael A. Jones, MD
POCT Program Director / August 12, 2010
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