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Test Code FS FETAL SCREEN

Important Note

  • The purpose of this test is to identify those post-partum women who may require more than a single dose of Rh-immune globulin.
  • If fetal screen is positive, KB “Kleihauer-Betke Fetal Hemoglobin Assay, Blood” will be performed at an additional charge.

Methodology

Mixed-Field Agglutination

 

Useful for determination of a feto-maternal bleed following delivery of an Rh-positive baby to an Rh-negative mother.

 

Specimen Requirements

Container/Tube: Lavender-top (EDTA) tube(s)

Specimen Volume: A minimum of 1 mL of whole blood

Collection Instructions:

  1. Draw blood from an Rh-negative mother, at least 1 hour post-delivery (but as soon as possible thereafter) of an Rh-positive baby. 
  2. Do not centrifuge. 
  3. Send specimen in original tube(s).
  4. If there is a delay in testing, store specimen at 1 - 10 oC

Note: 

  1. Rh status of mother and baby must have been established prior to drawing blood for fetal screen. Test results are valid only if mother is Rh-negative and baby is Rh-positive.
  2. n a weak D-positive infant, weakened agglutination may not detect a feto-maternal bleed exceeding 30 mL of whole blood.
  3. In cases of ABO incompatibility between mother and child, mother’s natural ABO antibodies may destroy any fetal cells in maternal blood specimen, causing a false-negative result.
  4. Autoantibodies in mother may cause a positive direct anti-globulin test and a false-positive fetal bleed screening test.

Specimen Stability

Store at 1 - 10 oC for up to 48 hours.

Grossly hemolyzed specimens are unacceptable

Day(s) Test Set Up

0Monday through Sunday

Reference Values

Negative: indicates that a large feto-maternal hemorrhage did not occur. Must not be interpreted to mean that Rh immune globulin is not required.

Positive: indicates the presence of D-positive red blood cells in possibly significant numbers in the maternal blood. KB “Kleihauer-Betke Fetal Hemoglobin Assay, Blood” will be performed to quantitate extent of feto-maternal hemorrhage.

Performing Laboratory

Logan Health Medical Center Laboratory

Test Classification and CPT Coding

83030-Fetal screen

85460-Kleihauer-Betke (if appropriate)

Specimen Transport Temperature

Refrigerate