Test Catalog

Test Id : FMBNY

Fetomaternal Bleed, New York, Blood

Useful For
Suggests clinical disorders or settings where the test may be helpful

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


This test is used only for specimens collected in New York state.

Method Name
A short description of the method used to perform the test

Flow Cytometry

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Fetomaternal Bleed, New York

Lists additional common names for a test, as an aid in searching

Fetal Hemoglobin

Fetal Maternal Bleed

Fetal Maternal Erythrocyte Distribution, Blood

Fetal Red Cells for Fetal Maternal Erythrocyte Distribution

Fetal-Maternal Erythrocyte Differentiation

Kleihauer Acid Elution (Fetal RBC's)


Maternal Erythrocyte Diff

Specimen Type
Describes the specimen type validated for testing

Whole Blood EDTA

Ordering Guidance

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


This test is for the detection of fetal bleed, it should not be used to detect the hereditary persistence of fetal hemoglobin (HPFH) or to detect fetal maternal hemorrhage in a mother with HPFH. For HPFH diagnosis, order HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood.

Shipping Instructions

Specimen must arrive within 5 days (preferably 24-72 hours) of collection. The New York State Department of Health recommends that samples are tested within 30 hours of collection.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Container/Tube: Lavender top (EDTA)

Specimen Volume: Full tube

Collection Instructions:

1. Do not centrifuge.

2. Invert several times to mix blood.

3. Send specimen in original tube. Do not aliquot as aliquoting into or out of a sample tube can adversely affect test results.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject
Clotted blood Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

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

Useful For
Suggests clinical disorders or settings where the test may be helpful

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


This test is used only for specimens collected in New York state.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

In hemolytic disease of the newborn, fetal red blood cells become coated with IgG alloantibody of maternal origin, which is directed against an antigen on the fetal cells that is of paternal origin and is 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 blood 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 blood 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 a Rh-positive fetus. Anti-D antibody binds to fetal D-positive red blood 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.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

< or =1.5 mL of fetal red blood cells in normal adults

Provides information to assist in interpretation of the test results

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 RBC. 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 post collection.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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


Due to differential RBC densities, aliquoting into or out of a sample tube can adversely affect the results.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Roback J, Combs MR, Grossman B, Hillyer C, eds: In: Technical manual. 16th ed. AABB Press; 2008:625-637, 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

3. Cohn CS, Delaney M, Johnson ST, Katz LM, eds: Technical Manual. 20th ed. AABB Press; 2020

Method Description
Describes how the test is performed and provides a method-specific reference

The fetomaternal bleed test identifies cells containing fetal hemoglobin. The cells are fixed and permeabilized and then incubated with monoclonal antibodies directed against fetal hemoglobin (HbF) and subsequently analyzed by flow cytometric methods. This test uses the FDA-approved Invitrogen Fetal Hemoglobin kit with fluorescein isothiocyanate-conjugated monoclonal antibody directed to HbF (HFH-01).(Package insert: Invitrogen Fetal Hemoglobin Test kit with FITC-conjugated Monoclonal Antibody Directed to HbF. Life Technologies Corporation; MAN 0003641, Rev 3.02 3/6/2013)


Rh immune globulin (RhIG) dose calculation: mL of fetal bleed/15 equals calculated doses of RhIG, then add a safety margin, ie, when the number to the right of the decimal point is less than 5, round down and add 1 dose (example: 2.2 = 2.0 + 1 = 3); when the number to the right of the decimal point is 5 or greater, round up to the next number and add 1 dose (example: 2.8 = 3.0 + 1 = 4). If fetal bleed is 1.5 mL or less, it will be reported as negative bleed and the RhIG dose will be 1.


RhD-Agglutination of red blood cells with an antiserum represents the presence of the corresponding antigen in the red blood cells.(Cohn CS, Delaney M, Johnson ST, Katz LM, eds: Technical Manual. 20th ed. AABB Press; 2020)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 day

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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 US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

88184-Flow cytometry; cell surface cytoplasmic

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
FMBNY Fetomaternal Bleed, New York 75308-7
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
28202 Fetal-Maternal Bleed 55730-6
28204 Mother's Rh 10331-7
28203 Rh Immune Globulin 55731-4
28246 Remarks 48767-8

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports