Fetal Rhesus-factor determination

We remind you that independent interpretation of the results is unacceptable, the information provided below is for reference purposes only.

Fetal Rhesus (Rh) factor determination is a non-invasive prenatal genetic test that allows the fetal RhD status to be determined by analyzing cell-free fetal DNA circulating in maternal blood.

The test is particularly relevant for RhD-negative pregnant women, as it allows assessment of the possibility of Rh incompatibility between the mother and fetus. If the fetus is RhD-positive, there is a possibility that the maternal immune system may develop anti-D antibodies, particularly in certain situations when fetal blood comes into contact with the maternal circulation.

Knowing the fetal RhD status may help individualize pregnancy monitoring and guide medical management regarding the prevention of Rh isoimmunization, according to the recommendations of the obstetrician-gynecologist.

Indications

• RhD-negative pregnant woman;
• assessment of the risk of Rh incompatibility between the mother and fetus;
• need to determine fetal RhD status without an invasive procedure;
• history of Rh isoimmunization or presence of anti-D antibodies in the context of medical assessment;
• previous pregnancies with Rh incompatibility;
• determination of the appropriate monitoring and prophylaxis strategy during pregnancy;
• recommendation by an obstetrician-gynecologist or medical geneticist.

Procedure

A maternal venous blood sample is collected for the test. Cell-free DNA fragments originating from the placenta circulate in the pregnant woman's blood and largely reflect the fetal genetic profile.

Cell-free DNA is isolated from the collected sample, and specific sequences of the RHD gene are analyzed using molecular biology methods. Detection of these sequences allows determination of the fetal RhD status.

The test is non-invasive for the fetus, as it requires only a maternal blood sample and does not involve direct collection of fetal biological material.

In certain situations, the result may be inconclusive, for example when the amount of circulating cell-free fetal DNA is insufficient. In such cases, repeat testing may be required according to the recommendations of the laboratory or physician.
 

Sources:

https://www.acog.org/womens-health/faqs/the-rh-factor-how-it-can-affect-your-pregnancy
https://www.mayoclinic.org/tests-procedures/rh-factor/about/pac-20394960
https://www.webmd.com/baby/rh-factor
https://www.msdmanuals.com/home/women-s-health-issues/complications-of-pregnancy/hemolytic-disease-of-the-fetus-and-newborn
https://www.redcrossblood.org/local-homepage/news/article/what-is-the-rh-factor--why-is-it-important-.html
https://www.sciencedaily.com/releases/2018/05/180515105651.htm

IMPORTANT!

It is crucial to remember that the information provided in this section is not intended for self-diagnosis or self-treatment. If you experience any pain or exacerbation of a condition, it is essential to consult a healthcare professional for diagnostic testing and appropriate treatment. Only a qualified specialist can make an accurate diagnosis and determine the appropriate treatment. To obtain the most accurate and consistent evaluation of test results, it is recommended to conduct tests at the same laboratory. This is because different laboratories may use different methods and units of measurement for similar tests.