ARUP's Laboratory Test Directory

Fetal Hemoglobin Determination for Fetomaternal Hemorrhage : 2001743

Mnemonic: FHGB

Methodology: Quantitative Flow Cytometry
Performed: Sun-Sat
Reported: 1-2 days
Specimen Required: Patient Prep: Maternal, pregnant or post-partum whole blood.

Collect: Lavender (EDTA) or pink (K2EDTA).

Specimen Preparation: Transport 5 mL whole blood. (Min: 0.5 mL)

Storage/Transport Temperature: Refrigerated.

Unacceptable Conditions: Frozen specimens. Clotted or hemolyzed specimens. Specimens older than 72 hours. Specimens from males or non-pregnant females.

Stability (collection to initiation of testing): Ambient: 12 hours; Refrigerated: 72 hours; Frozen: Unacceptable
Reference Interval:
By report
Interpretive Data: The performance characteristics of this test were determined by ARUP Laboratories, Inc.

See Compliance Statement B: www.aruplab.com/CS
 
Result Interpretation
% Fetal RBCs The fetal RBC percentage is directly measured by flow cytometry and gives the percentage of fetal RBCs in maternal circulation resulting from recent fetal-maternal hemorrhage.  Post-partum, some fetal cells are expected (0.04% plus or minus 0.024%, mean plus or minus SD).
Fetal Blood Volume Fetal blood volume is the volume of feto-maternal hemorrhage and is calculated from the % Fetal RBCs by multiplying by 50, assuming a maternal blood volume of 5000 mL and a hematocrit of 50%.  Post-partum, some feto-maternal hemorrhage is expected (2.0 mL plus or minus 1.2 mL, mean plus or minus SD).
RhIg Required Given the delivery of an RhD+ fetus from an RhD- mother, the amount of IM RhIg (anti-RhD immunoglobulin) required to avoid sensitization is 10 µg for each mL of feto-maternal hemorrhage.
RhIg Vials Required Given the delivery of an RhD+ fetus from an RhD- mother, one (1) vial of RhD (300 µg vial administered IM) is recommended when the amount of RhD required is <300 µg.  From 300-600 µg, 2 vials are recommended; from 600-900 µg, 3 vials are recommended; from 900-1200 µg, 4 vials are recommended; from 1200-1500 µg, 5 vials are recommended and so forth.

Note: This test should only be used to detect and quantify the extent of fetomaternal hemorrhage, in pregnant or post-partum women who need to be assessed for Rh immune globulin (e.g. RhoGAM®) or fetal-maternal bleeds. 

For routine fetal hemoglobin (Hb F) testing, please order Hemoglobin Evaluation with Reflex to Electrophoresis and/or RBC Solubility (0050610).
CPT Code(s): 86356
Cross References: Fetomaternal Bleed by Flow Cytometry (Blood) (Fetal Hemoglobin Determination for Fetomaternal Hemorrhage) , Kleihauer-Betke Acid Elution for Fetal RBC Detection (Fetal Hemoglobin Determination for Fetomaternal Hemorrhage)