What is integrated prenatal screening?

Integrated prenatal screening is a combination of three different tests used to determine that the child is born with Down syndrome, trisomy 18 or open nerve tube defects. Testing can start after 11 weeks of pregnancy and the results are usually available within 16 to 17 weeks of pregnancy. Although integrated prenatal screening is not a diagnostic tool, pregnant women and doctors can give a good idea of ​​whether further testing is required. It is usually done between the 11th and 13th week of pregnancy of a woman and is often one of the first tests given to pregnant women. For the purposes of this screening, ultrasound focuses on the amount of fetal fluid behind the neck of the fetus; This test is known specifically as nuchal scanning. Fruits with higher than normal amounts of fetal fluid behind the neck are also exposed to a greater risk of down syndrome, also known as trisomy 21, trisomy 18 and various open defects of the nerve tube.

Between 10 and 13 weeks of pregnancy, a blood test is performed to determine the levels of plasma protein and (Papp-A) associated with pregnancy in the blood of the expectant mother. This is the second part of the integrated prenatal screening. All pregnant women have this specific protein in their blood; If the levels are low, it could also indicate that the fetus is at greater risk of trisomy 21, trisomy 18 and open defects of the nerve tube.

The final test in integrated prenatal screening is another blood test, usually performed between 16 and 17 weeks of pregnancy. This test measures several different protein levels: inhibin and, uninterined estriol, alpha fetoprotein and human chorionic gonadotropin. Once this testing is completed, the results of the entire integrated prenatal screening will be available.

The information collected by these three tests can estimate the likelihood of a fetus that Down's syndrome has a little over 90%. CanAlso determine the chances of trisomy 18 in 90% of cases and the chance of a defect of an open nerve tube, such as an antencephalia or spina bifida, in 80% of cases. These tests provide doctors and pregnant women with the probability of fetus; This is not a diagnostic tool.

Each 30 women receive one abnormal results on integrated prenatal screening. The abnormal test result simply means that the fetus is at greater risk than the average for the development of these defects. If a woman receives abnormal test results, she will usually have the opportunity to undergo further diagnostic testing.