What are the other Names for this Test? (Equivalent Terms)
- 4-Marker Screen for Fetal Defects during Pregnancy
- hCG (Human Chorionic Gonadotropin) & uE3 (Unconjugated Estriol) Screen as part of Triple Screen Test during Pregnancy
- msAFP; Triple Screen with AFP (Alpha-Fetoprotein)
What is Triple Screen Test during Pregnancy? (Background Information)
- Triple Screening Test during Pregnancy: In order to investigate whether the developing fetus is at risk of certain birth defects, the mother’s blood is tested during pregnancy, between the 15th & 22nd week
- The test does not specifically identify or diagnose the various congenital defects that could occur; it only indicates the degree of risk the baby is involved in (if any)
- The congenital disorders that might arise are chromosomal abnormalities (like Down syndrome, Edwards syndrome, etc.), or neural tube defects (like spina bifida), or other conditions
- If the blood is tested for three hormones, it is called Triple Screen Test. If the fourth hormone is also measured then, it is called Quad Screen Test
The test, analyses the presence and quantities of the following three hormones as part of Triple Screen Test that are produced during pregnancy:
- AFP (alpha-fetoprotein) - a protein produced by the developing baby tissue
- hCG (human chorionic gonadotropin) - a hormone produced in the placenta
- uE3 (unconjugated estriol) - a hormone estrogen produced through metabolism in the fetus
If additional test for Inhibin A (a placenta-produced hormone) is added to the Triple Screen; then, it is called a Quad Screen Test.
What are the Clinical Indications for performing the Triple Screen Test during Pregnancy?
All pregnant women in the second trimester (between weeks 15 and 22) are tested. Those in the following categories are at a higher risk:
- Women over 35 years old
- Those taking insulin for treating diabetes
- Women having a family history of birth defects
- Use of certain medications
- Exposure to high radiation levels
- Having complications, viral infections, during pregnancy
Note: The test is most accurate when pregnant women are tested between gestation weeks, 16 and 18.
How is the Specimen Collected for Triple Screen Test during Pregnancy?
Sample required: Blood
Process: Insertion of needle into a vein (arm).
Preparation required: None
What is the Significance of the Triple Screen Test during Pregnancy Result?
The tests are not diagnostic in nature; positive results indicate that further examinations (imaging studies, amniocentesis) are required to analyze the condition and confirm disorders (if any).
Since various factors (age, family background, gestation week of the pregnant woman, etc.) are involved in interpreting the test result, not all cases of elevated levels of tested proteins mean a presence of abnormalities. It is also important to note that not all fetal abnormalities may be revealed during this test.
A genetic counselor or a medical practitioner is best positioned to interpret the results and make suitable recommendations.
- Low uE3 & hCG levels with variable AFP level, indicate Edwards Syndrome (also called trisomy of chromosome 18), with approximately 80% accuracy
- Low AFP & uE3 levels, high hCG & inhibin A levels, indicate Down Syndrome with approximately 70% accuracy
- If AFP levels are elevated and other parameters normal, the possibility of a neural tube defect is high
- High AFP levels could also mean that there could be more than one fetus (such as twins or triplets). Therefore, an increased level of alpha-fetoprotein does not always mean the presence a congenital defect
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
Many factors should be considered before interpreting the results of Triple or Quad Screen Test. It is highly advised to determine factors, such as:
- The exact gestational age of the fetus
- Age of the pregnant mom
- The gestational age of pregnancy
- Weight of the pregnant woman
And ascertain all other relevant factors, prior to performing the screening and interpreting test results.
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.