Everything that You Must Know About Prenatal Tests

Prenatal tests are procedures to detect whether the growing fetus and the mother are in fit and fine condition. These tests are conducted to check whether the baby is growing healthily and to detect if the fetus is suffering from any birth defects, genetic defects or any kind of chromosomal abnormalities.

As soon as a woman gets pregnant, she is prescribed a series of prenatal tests. Most of these tests are done during first trimester while some others are done in the latter trimesters. It is always advisable to go for these tests as soon as prescribed to avoid any complications later in pregnancy.

Following are the types of prenatal tests that a woman can expect to undergo during her pregnancy.

General or routine tests: To start with, prenatal tests begin with the normal blood and urine testing. The blood tests help in diagnosing problems such as Ph- negative diseases and checking whether the mother is anemic and whether she suffers from any kind of STDs. With the help of urine tests, the obstetrician gets to know about presence of gestational diabetes, preeclampsia and bladder infections in the mother’s body. Apart from this, the blood pressure of the mother is noted in every visit because high or low blood pressure can be harmful to the health of the baby. Doctors also perform vaginal smear or pap to check for any unwanted bacteria or abnormal cervical cells which may be harmful to the baby.

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These are the general routine test which your doctor performs at the very first visit:

Ultrasounds: An ultrasound is an important part of prenatal testing. Ultrasound helps in keeping a track of the baby’s development and identifying any health problems or abnormalities. Besides that, the sex of the baby can also be detected through ultrasound. Generally, the first ultrasound is done near to 10th week of pregnancy while the next two or sometimes three are done in second and third trimesters.

Apart from the general ultrasounds, some women are also suggested to go for NT scan or Nuchal translucency scan. This scan checks for the size of the Nuchal fluid that surrounds the baby’s neck. The size of this fluid helps in determining whether the baby suffers from Down’s syndrome.

Prenatal genetic screenings: Some women who are above the age of 35 are advised to go for prenatal genetic screening tests also. These tests help in detecting the probability of any kind of chromosomal abnormalities such as Down’s syndrome in the baby. There are several kinds of such tests available in the market.

Double Marker Test is a blood test that checks for two elements namely free Beta HCG (Human Chorionic Gonadotropin) and PAPP-A (a plasma protein) in the mother’s blood. If the level of HCG is high and plasma protein is low, fetus is suspected to have some kind of intellectual disability. Similarly, there is Triple Marker Test which checks for three elements (HCG, Estriol, and Alpha-fetoprotein )instead of two. As the sensitivity of these tests is not too high, doctors prefer other non-invasive prenatal testing techniques such as NACE (Non-invasive Analysis for Chromosomal Examination) which gives results with higher accuracy. Moreover, being non-invasive, NACE is a risk-free procedure and thus there is no harm to the mother and the fetus with this test. It is a blood test which checks for the cell free fetal DNA in the mother’s plasma. The chances of false positives are just 0.1% with NACE.

Prenatal genetic confirmatory tests: It should be noted that tests such as Double Marker Test, Triple Marker Test are screening tests and if the results come out to be positive, one has to go for confirmatory diagnosis. There are mainly two types of confirmatory tests namely Amniocentesis and Chorionic Villus sampling (CVS).

Amniocentesis uses amniotic fluid, the water that surrounds the fetus, to ascertain whether the baby has any chromosomal abnormality. On the other hand, in CVS, some fetal tissue (chorionic villi) is extracted from placenta and tested to know for any kind of genetic defect or chromosomal abnormality in the fetus.

Unfortunately, these tests are invasive and pose some risk both to the mother and the baby. Therefore, it is suggested that a patient should first go for the highly accurate non-invasive prenatal screening test-NACE and then on the basis of its results, the patient should go for the confirmatory invasive test.

Apart from these tests, there can be some other tests but they are not universal and depend on the patient’s condition. Prenatal tests, done timely as prescribed, help you to avoid any complications later in pregnancy and thus ensure a safe and happy pregnancy period.