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Test ID FMBNY Fetomaternal Bleed, New York

Reporting Name

Fetomaternal Bleed, New York

Useful For

Determining the volume of fetal-to-maternal hemorrhage for the purposes of recommending an increased dose of the Rh immune globulin


This is only for specimens collected in New York state.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Whole Blood EDTA

Advisory Information

This test is for the detection of fetal bleed, it should not be used to detect the hereditary persistence of fetal hemoglobin (see HPFH / Hemoglobin F, Red Cell Distribution, Blood) or to detect fetal maternal hemorrhage in a mother with hereditary persistence of fetal hemoglobin.


This test is only available for patients from New York State. For patients from other locations, order FMB / Fetomaternal Bleed, Flow Cytometry, Blood.

Shipping Instructions

Specimen must arrive within 120 hours (preferably 24-72 hours) of draw. The New York State Department of Health recommends that samples are tested within 30 hours of draw.

Specimen Required

Container/Tube: Lavender top (EDTA)

Specimen Volume: Full tube

Collection Instructions:

1. Do not centrifuge or aliquot.

2. Invert several times to mix blood.

3. Send specimen in original tube.

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood EDTA Refrigerated (preferred) 5 days
  Ambient  5 days

Reference Values

≤1.5 mL of fetal RBCs in normal adults

Day(s) and Time(s) Performed

Monday through Sunday; Varies

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

88184-Flow cytometry; cell surface cytoplasmic

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FMBNY Fetomaternal Bleed, New York In Process


Result ID Test Result Name Result LOINC Value
28204 Mother's Rh 10331-7
28202 Fetal-Maternal Bleed 55730-6
28203 Rh Immune Globulin 55731-4
28246 Remarks 48767-8

Clinical Information

In hemolytic disease of the newborn, fetal red cells become coated with IgG alloantibody of maternal origin, directed against an antigen on the fetal cells that is of paternal origin and absent on maternal cells. The IgG-coated cells undergo accelerated destruction, both before and after birth. The clinical severity of the disease can vary from intrauterine death to hematological abnormalities detected only if blood from an apparently healthy infant is subject to serologic testing.


Pregnancy causes immunization when fetal red cells possessing a paternal antigen foreign to the mother enter the maternal circulation, an event described as fetomaternal hemorrhage (FMH). FMH occurs in up to 75% of pregnancies, usually during the third trimester and immediately after delivery. Delivery is the most common immunizing event, but fetal red cells can also enter the mother's circulation after amniocentesis, spontaneous or induced abortion, chorionic villus sampling, cordocentesis, or rupture of an ectopic pregnancy, as well as blunt trauma to the abdomen.(1)


Rh immune globulin (RhIG, anti-D antibody) is given to Rh-negative mothers who are pregnant with an Rh-positive fetus. Anti-D antibody binds to fetal D-positive red cells, preventing development of the maternal immune response. RhIG can be given either before or after delivery. The volume of FMH determines the dose of RhIG to be administered.


Greater than 15 mL of fetal red blood cells (RBC) (30 mL of fetal whole blood) is consistent with significant fetomaternal hemorrhage (FMH).


A recommended dose of Rh immune globulin (RhIG) will be reported for all specimens. One 300-mcg dose of RhIG protects against a FMH of 30 mL of D-positive fetal whole blood or 15 mL of D-positive fetal RBCs. Recommended standard of practice is to administer RhIG within 72 hours of the fetomaternal bleed for optimal protective effects. The effectiveness of RhIG decreases beyond 72 hours postexposure but may still be clinically warranted. This assay has been validated out to 5 days postcollection.


Clinical conditions exist that may result in an increased level of fetal hemoglobin-containing red cells, including hereditary persistence of fetal hemoglobin and thalassemia. Such red cells (also referred to as F cells) are detected by this assay. Results must be interpreted with caution in these situations.

Clinical Reference

1. Technical manual. Sixteenth edition. Edited by J Roback, MR Combs, B Grossman, C Hillyer. Bethesda, MD, AABB Press, 2008, pp 625-637, pp 888

2. Iyer R, McElhinney B, Heasley N, et al: False positive Kleihauer tests and unnecessary administration of anti-D immunoglobulin. Clin Lab Haematol 2003;25:405-408

Analytic Time

Same day/1 day

Reject Due To


Mild reject; Gross reject


Mild reject; Gross reject


Mild reject; Gross reject


Clotted blood

NY State Approved


Method Name

Flow Cytometry