Understanding prenatal diagnosis: Techniques, benefits, and ethical considerations

Prenatal diagnosis involves medical procedures and tests conducted during pregnancy to detect genetic disorders, birth defects, or other conditions in the fetus. These assessments help expectant parents make informed decisions about their pregnancy and potential interventions. Leading consultant in obstetrics and maternal and foetal medicine Dr Panicos Shangaris explains everything you need to know about prenatal diagnosis.

What is prenatal diagnosis, and why is it recommended during pregnancy?

Prenatal diagnosis involves testing the fetus during pregnancy to identify any abnormalities in its development or to diagnose certain genetic or chromosomal conditions. Potential health issues should be detected early to help ensure the health of both the mother and the fetus. This early detection can allow for better planning around the birth, management of the pregnancy, and preparation for any medical treatment that may be needed after birth.

What are the different methods of prenatal diagnosis, and how are they performed?

Several methods are used for prenatal diagnosis, each suitable for different stages of pregnancy and specific diagnostic needs:

• Ultrasound scans: These are non-invasive and routinely used to check the fetus's structure and growth.
• Blood tests: These can identify markers associated with genetic disorders or potential complications such as preeclampsia.
• Amniocentesis (typically performed after 15 weeks): These involve taking a small amount of amniotic fluid using a needle inserted into the uterus under ultrasound guidance. The DNA from this fluid is extracted and analysed for chromosomal and genetic abnormalities.
• Chorionic Villus Sampling (CVS) (performed after 11 weeks): A biopsy and a cell sample are taken from the placenta to test for genetic/ chromosomal disorders.
• Non-invasive prenatal testing (NIPT): This analyses fetal DNA in the maternal bloodstream to detect certain genetic abnormalities as early as ten weeks into the pregnancy.

What conditions or abnormalities can prenatal diagnosis detect in the unborn baby?

Prenatal diagnosis can detect a range of conditions and abnormalities, including:

• Chromosomal abnormalities such as Down syndrome, Edwards syndrome, and Patau syndrome.
• Genetic disorders like cystic fibrosis, sickle cell disease, and Tay-Sachs disease.
• Structural abnormalities such as spina bifida and congenital heart defects.
• Complications in pregnancy that could affect fetal growth and the health of the mother, such as small for gestation fetus.

Are there any risks or limitations associated with prenatal diagnostic procedures?

While prenatal diagnostic procedures are invaluable, they carry some risks and limitations:

• Invasive tests like amniocentesis and CVS can carry a small risk (1%) of miscarriage.
• False positives or negatives can occur, potentially leading to further unnecessary testing or undue stress.
• Not all conditions can be detected, and some tests may not provide definitive answers, requiring further diagnostic procedures.

How does prenatal diagnosis contribute to informed decision-making during pregnancy?

Prenatal diagnosis is crucial for informed decision-making during pregnancy. It provides expectant parents and healthcare providers with important information about the foetus’s health and development, enabling:

• Early intervention and treatment planning for conditions that can be managed in utero or immediately after birth.
• Preparation for the birth of a child with special needs, including connecting with the wider multidisciplinary team, support networks and services.
• In some cases, decisions about continuing the pregnancy can be informed by a clear understanding of the health challenges the baby might face.

This proactive approach allows parents and healthcare teams to tailor prenatal and postnatal care to achieve the best possible outcomes for both mother and child.

If you would like to learn more about prenatal diagnosis and would like to book a consultation with Dr Shangaris, do not hesitate to do so by visiting his Top Doctors profile today.