Kleihauer test

Blood Transfusion

Purpose

Transplacental or fetomaternal haemorrhage (FMH) may occur during pregnancy or at the time of delivery, and lead to immunisation of the D antigen if the mother is D negative and the baby D positive. It is important to assess the volume of FMH to determine the dose of anti-D immunoglobulin required by a D negative woman to prevent sensitisation. The anti-D immunoglobulin must be given within 72 hours of the sensitising event, although some protection may be offered up to 10 days later.

A test for FMH should be undertaken on:

• D negative women following delivery of a D positive baby or if no fetal blood group available
• Following all potentially sensitising events in D negative women after 20 weeks gestation i.e.:

> Amniocentesis, cordocentesis

> Antepartum haemorrhage, PV bleeding in pregnancy

> External cephalic version

> Fall, abdominal trauma (direct or indirect)

> Intrauterine death, still birth

> In-utero therapeutic interventions (transfusion, surgery)

> Miscarriage

> Therapeutic termination of pregnancy

> Cell salvage

> Following IUD in Rh D positive women

A test for FMH estimation is not required:

• When the sensitising event is before 20 weeks, because the fetal blood volume is insufficient to exceed that covered by the minimum 500iu anti-D immunoglobulin dose in standard use.
• When the woman is known to have immune anti-D. NB if unable to distinguish between passive and immune anti-D, FMH estimation should be performed.
• When the fetus/baby is known or predicted by cffDNA testing to be D negative
• When the woman is D positive
• In D positive women with unexplained abdominal pain in late pregnancy. The FMH test is of limited use. More sensitive and specific tests exist to investigate placental abruption

Notes

• A Kleihauer test is a test to determine if there has been and the size of Foeto-maternal haemorrhage (FMH)
• FMH estimation is is performed to ensure that pregnant women who have undergone potentially sensitising events are given adequate quantities of anti-D.
• 500IU of anti-D prophylaxis will clear a 4mL bleed
• If the FMH is estimated to be >2mLs, the sample will be referred to NHSBT, Bristol, Filton for quantitation by Flow Cytometry
• The following factors are known to significantly affect the performance of the examination or the interpretation of the results: lipaemia, sample clotted (if EDTA), haemolysed. Any sample displaying these factors cannot be processed and will be rejected.

• This test should be performed and any subsequent Anti-D required administered within 72 hours of delivery, sensitising event or invasive procedure.
• Anti-D will be issued from the laboratory if required.
• For further information see Trust Clinical Guidelines Anti-D immunoglobulin during pregnancy (M1071).
• Performed at GRH.

Sample Requirements

EDTA tube - 6mL

or
EDTA 4mL

Required Information

Sample and request form must be labelled correctly with 4 points of reference:

1. Forename
2. Surname
3. Date of birth
4. Unique identification number

The sample must be labelled, signed and dated by the person taking the blood

The sample tube must be in date

Unlabelled, incorrectly, altered or inadequately labelled samples will not be accepted. No specimen is considered unrepeatable

Turnaround time

Within 24 hours