Kleihauer-Betke test introduction

The Kleihauer-Betke test, commonly known as the Betke stain or acid elution test, detects foetal RBCs in the maternal circulation. It is used for maternal-fetal haemorrhage, especially during pregnancy, delivery, or obstetric trauma.

The test was invented in 1957 by Arthur W. Kleihauer and Melvin H. Betke. It was first used to monitor fetal-maternal haemorrhage in Rh-negative women to guide Rh immune globulin (RhIg) treatment to avoid isoimmunization, a condition in which the mother’s immune system creates antibodies against the foetal blood cells.

The Kleihauer-Betke test works because foetal RBCs have foetal haemoglobin (HbF) instead of adult haemoglobin (HbA). HbF resists acid elution, enabling the test to distinguish foetal and maternal RBCs.

The test involves mixing maternal blood with an acid solution. This acid solution preferentially eliminates maternal HbA from RBCs while preserving foetal HbF. Stained and counted foetal RBCs follow. Fetal-maternal haemorrhage may be measured by comparing foetal RBCs to total RBCs.

In Rh sensitization, a pregnant woman with Rh-negative blood is exposed to Rh-positive foetal blood. The Kleihauer-Betke test is helpful. It helps detect the quantity of foetal blood that has passed into the maternal circulation, allowing for RhIg administration to avoid further sensitization.

In addition to Rh sensitization, the Kleihauer-Betke test may be used to determine fetal-maternal haemorrhage after trauma or foetal death.

The Kleihauer-Betke exam may not be suited for all scenarios. Based on test findings, healthcare practitioners should evaluate other clinical criteria and confer with experts to make educated RhIg administration or treatment choices.

Purpose of Kleihauer-Betke test

The Kleihauer-Betke test detects foetal red blood cells in maternal circulation. It is utilised for maternal-fetal haemorrhage, especially in Rh-negative pregnancies that risk sensitization to Rh-positive foetal blood.

The test lets doctors detect fetal-maternal haemorrhage and provide Rh immune globulin (RhIg) to avoid sensitization. Sensitization occurs when the mother’s immune system attacks Rh-positive foetal blood. This may cause neonatal hemolytic illness in later pregnancies.

The Kleihauer-Betke test quantifies foetal RBCs in the maternal circulation to determine RhIg dose to avoid sensitization. It protects Rh-negative women against Rh sensitization, lowering the likelihood of subsequent problems.

The Kleihauer-Betke test may also measure fetal-maternal haemorrhage after trauma or foetal death. It estimates the volume of foetal blood in the maternal circulation, helping with management and care.

The Kleihauer-Betke test helps doctors assess fetal-maternal haemorrhage and determine Rh sensitization prevention measures.

Procedure of Kleihauer-Betke test

Kleihauer-Betke test:

Venipuncture is used to draw maternal blood. EDTA anticoagulant tubes prevent clotting while collecting the sample.

A little drop of maternal blood is used to make a thin blood smear on a glass slide. Smears are air-dried.

Acid Elution: The slide is submerged in an acidic buffer, usually 0.8% citric acid. The slide is incubated in acid for 3-5 minutes. The acid solution preferentially eliminates adult haemoglobin (HbA) from maternal red blood cells (RBCs) while preserving foetal HbF.

Washing: After acid elution, the slide is washed with water to remove acid and HbA.

Staining: HbF-containing foetal RBCs are stained with an eosin-cresyl blue solution. This staining distinguishes foetal RBCs from other cells and detritus.

Laboratory technician or pathologist examines stained slide under microscope. Eosin staining turns foetal RBCs pink or crimson, whereas other cells and detritus are stained differently. The technician averages foetal RBC counts from numerous fields of view.

Fetal-maternal haemorrhage (FMH) is estimated by counting foetal RBCs. The percentage or volume of foetal blood in the maternal circulation is given as a percentage or volume.

To get accurate Kleihauer-Betke test findings, lab staff should be educated. The clinical context, Rh immune globulin (RhIg) administration, and other treatment considerations should be considered when interpreting test findings.

Indication of Kleihauer-Betke test

When to use Kleihauer-Betke:

Rh Sensitization: Rh-negative women at risk of sensitization to Rh-positive foetal blood are the Kleihauer-Betke test’s main indication. Pregnancy, labour, and obstetric stress may cause fetal-maternal haemorrhage. The test determines fetal-maternal haemorrhage to avoid sensitization with Rh immune globulin (RhIg).

The test may also be used to assess fetal-maternal haemorrhage regardless of Rh status. Traumatic birth or foetal death may cause this. Determining the degree of fetal-maternal haemorrhage helps with mother care.

Evaluation of Foetal Demise: The Kleihauer-Betke test may detect foetal blood in the maternal bloodstream when a foetus dies in utero. This information helps with mother’s health and issues.

Not all pregnancies get the Kleihauer-Betke test. It is designated for instances of fetal-maternal haemorrhage in Rh-negative moms or substantial trauma or foetal death. Clinicians use clinical judgement and specific reasons to order the test.

Types of Kleihauer-Betke test

No Kleihauer-Betke test “types” exist. The Kleihauer-Betke test detects foetal red blood cells (RBCs) in maternal blood.

In certain scenarios or labs, the Kleihauer-Betke test may be modified. Variations include:

Quantitative Kleihauer-Betke Test: This test estimates fetal-maternal haemorrhage as a percentage or volume. A more exact quantitative measurement may be needed. Foetal RBC quantification requires extra computations or specialised equipment.

Kleihauer-Betke Test: Flow cytometry may measure fetal-maternal haemorrhage. It includes labelling foetal RBCs with fluorescent markers and employing flow cytometry to sort and quantify them. This approach improves foetal RBC measurement.

These variants may only be obtained in specialised labs or under certain conditions. The Kleihauer-Betke test is the most frequent way to measure fetal-maternal haemorrhage and determine RhIg administration. Clinical circumstances, laboratory practises, and resources determine the test.

Risk of Kleihauer-Betke test

Kleihauer-Betke testing is low-risk. It requires blood sampling and lab processing. Test hazards include:

Discomfort or Pain: Needle insertion may cause slight discomfort or pain during blood sample collection. This is generally brief.

Bruising or Hematoma: The blood sample location may bruise or hematoma sometimes. Minor skin bleeding during or after the treatment might cause this. Pressing the spot after the blood sample reduces this danger.

Puncture site infection is uncommon. Sterile blood sample collection reduces infection risk.

The Kleihauer-Betke test doesn’t harm the pregnancy or foetus. The treatment is done on maternal blood samples without uterine manipulation.

In cases of maternal-fetal haemorrhage or Rh sensitization, the test is usually done. Qualified healthcare practitioners should assess and manage test findings based on clinical context and patient characteristics.

Before the Kleihauer-Betke test, talk to your doctor about any concerns or hazards. They can answer your concerns and give personalised information.

Results of Kleihauer-Betke test

The Kleihauer-Betke test detects foetal RBCs in the maternal circulation. Test results often read:

Percentage of Fetal-Maternal Haemorrhage (FMH): Foetal RBCs are usually reported as a percentage of the overall RBC population. “2%” means 2% of the maternal RBCs on the slide are foetal. This percentage estimates the amount of foetal blood in the maternal circulation.

Fetal-Maternal Haemorrhage Volume: Some results are provided in volumes. This is crucial for quantifying foetal blood. Foetal blood in the maternal circulation is estimated in millilitres (mL) or microliters (μL).

Clinical environment and test purpose determine test interpretation. The findings may help treat Rh-negative moms at risk of sensitization or fetal-maternal haemorrhage after trauma or foetal death.

Test findings and clinical data will help doctors decide what to do. Rh immune globulin (RhIg) to avoid sensitization, monitoring and follow-up changes, and further therapies may be needed.

The Kleihauer-Betke test findings should be interpreted by trained maternal-fetal medicine specialists. They’ll analyse patient variables, the test’s indication, and applicable recommendations or procedures to make educated judgements based on the findings.

Conclusion of Kleihauer-Betke test

In conclusion, the Kleihauer-Betke test detects foetal RBCs in the maternal circulation. In Rh-negative women who may be sensitised to Rh-positive foetal blood, it is recommended for maternal-fetal haemorrhage.

The test guides treatment choices such administering Rh immune globulin (RhIg) to avoid sensitization or assessing fetal-maternal haemorrhage after trauma or foetal death.

The Kleihauer-Betke test usually reports foetal RBC % or fetal-maternal haemorrhage volume. These findings estimate foetal blood in the maternal circulation.

Qualified healthcare providers should evaluate test findings based on the patient’s clinical situation, applicable recommendations, and test indications. The findings are utilised with other clinical data to guide management, therapy, and interventions.

The Kleihauer-Betke test assesses fetal-maternal haemorrhage and prevents Rh sensitization, improving the treatment of pregnant women and their unborn children.


The Kleihauer-Betke test’s goal?
The Kleihauer-Betke test detects foetal red blood cells in maternal circulation. It is utilised in maternal-fetal haemorrhage, particularly in Rh-negative women at risk of sensitization to Rh-positive foetal blood.

Kleihauer-Betke test: how?
The Kleihauer-Betke test includes obtaining a maternal blood sample, producing a blood smear, acid eluting maternal haemoglobin, staining foetal RBCs, and evaluating the stained slide under a microscope. Counting foetal RBCs estimates fetal-maternal haemorrhage.

Kleihauer-Betke tests what?
The Kleihauer-Betke test counts maternal foetal red blood cells. The test estimates fetal-maternal haemorrhage volume, which helps determine Rh immune globulin (RhIg) dosage and severity.

A positive Kleihauer-Betke test indicates?
A positive Kleihauer-Betke test confirms maternal circulation of foetal red blood cells. Fetal-maternal haemorrhage causes this. The test result determines if RhIg is needed to avoid Rh sensitization or advises treatment.

Can the Kleihauer-Betke test be done anytime throughout pregnancy?
At any stage of pregnancy, the Kleihauer-Betke test may detect fetal-maternal haemorrhage. It may be done during standard prenatal care or in emergencies such trauma, foetal death, or haemorrhage.

Is the Kleihauer-Betke test risky?
Low-risk Kleihauer-Betke test. Minor discomfort or pain during blood sample collection, puncture site bruising or hematoma, and occasional infection are the main hazards. The dangers are minor and do not directly harm the pregnancy or foetus.

These are generic replies; specific instances may differ. Talk to a doctor about Kleihauer-Betke exam questions.


Myth: The Kleihauer-Betke test can measure maternal foetal blood.
Fact: The Kleihauer-Betke test estimates fetal-maternal haemorrhage volume but does not quantify it. The test can estimate foetal blood cells, but not precisely.

Myth: Only Rh-negative moms undergo Kleihauer-Betke testing.
Fact: The Kleihauer-Betke test is used in Rh-negative women to determine the risk of Rh sensitization, but it may also be employed in instances of fetal-maternal haemorrhage after trauma or foetal death. The test determines haemorrhage and guides treatment.

Myth: A negative Kleihauer-Betke test eliminates Rh sensitivity.
Fact: A negative Kleihauer-Betke test implies limited fetal-maternal haemorrhage, although Rh sensitization is still possible. The test may miss some foetal blood. RhIg may still be advised depending on gestational age or clinical judgement.

Myth: All pregnancies undergo Kleihauer-Betke testing.
Fact: Not all pregnancies undergo Kleihauer-Betke testing. It is recommended for Rh-negative moms at risk of sensitization or suspected fetal-maternal haemorrhage after trauma or foetal death. Clinical judgement and healthcare professional indications define the test.

Myth: The Kleihauer-Betke test endangers the pregnancy or foetus.
The Kleihauer-Betke test is safe for the mother and foetus. The test seldom causes pain or bruising. The test’s maternal-fetal management advantages exceed its negligible dangers.

Note that individual circumstances may differ, therefore it’s recommended to speak with a healthcare practitioner or competent medical expert for personalised information and to resolve any Kleihauer-Betke test issues or concerns.


Kleihauer-Betke test: Detects foetal red blood cells (RBCs) in maternal blood.

Rh sensitization: Rh-negative people acquire antibodies against Rh-positive blood following exposure to Rh-positive foetal blood.

Trauma, placental abruption, foetal death, or other obstetric circumstances may cause fetal-maternal haemorrhage.

Rh immune globulin (RhIg): Used to avoid sensitization in Rh-negative women by inhibiting the immune response to Rh-positive foetal blood.

Maternal-fetal blood group incompatibility: When the mother and foetus have different blood types, immunological responses and problems may occur.

Rh factor: Red blood cell antigen that establishes Rh blood group. Rh-positive and Rh-negative people exist.

In fetal-maternal haemorrhage, foetal red blood cells may enter the maternal circulation.

Acid elution: The Kleihauer-Betke test uses acid to extract maternal haemoglobin and stain foetal red blood cells.

Blood smear: A thin film of blood on a glass slide for microscopic cell investigation.

Staining: Applying dyes or stains to cells on a slide to make them visible and countable.

Red blood cells deliver oxygen through haemoglobin.

Sensitization: When the immune system responds to an antigen and produces specific antibodies.

Rh-negative: Red blood cells without Rh antigen.

Rh-positive: Red blood cells with Rh antigen.

Trauma, injury, or vascular problems may cause haemorrhage.

Prenatal care: Health and foetus monitoring for pregnant women.

Trauma: Accidental or external harm.

Prenatal foetal death.

Obstetric: Pregnancy, delivery, and prenatal care.

Hemolysis: Red blood cell disintegration.

Quantitative: Quantity-related.

Volume measurement: Quantifying a material or entity using millilitres or microliters.

Flow cytometry: A laboratory method that employs lasers to sort cells by physical and chemical features.

Fluorescent markers: Substances that glow when activated by a certain wavelength of light, used to label or identify cells or structures.

Microliters (μL): Used to measure minuscule volumes of liquid.

The mother’s blood circulation.

Clinical context: A patient’s clinical setting and variables.

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