Second trimester Quadruple test
The Second Trimester Quadruple Test, also known as the Quad Screen, is a maternal blood test used during the second trimester to estimate the chance of certain chromosomal conditions and fetal structural abnormalities. The test measures four substances in the mother’s blood — alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol (uE3) and inhibin A. It is generally performed between 15 and 22 weeks of pregnancy, with screening often most accurate around 16–18 weeks.
Four-Marker Blood
Individualized Risk Assessment
Second trimester Quadruple test
Alpha-Fetoprotein (AFP)
Human Chorionic Gonadotropin (hCG)
Unconjugated Estriol (uE3)
Inhibin A
Down Syndrome Screening
Edwards Syndrome Screening
Neural Tube Defect Screening
Gestational Age Assessment
Multiple Pregnancy Consideration
Overall Risk Assessment
When Is It Recommended?
The Second Trimester Quadruple Test is generally performed between 15 and 22 weeks of pregnancy and is often most accurate between 16 and 18 weeks.
- It may be offered when second-trimester screening for chromosomal conditions is required.
- It may be considered when first-trimester screening was not performed or was not available.
- It can provide screening information about certain fetal structural abnormalities through AFP assessment.
- It may be used when an individualized assessment of chromosomal risk is required.
- Accurate gestational dating is important for reliable interpretation.
- In multiple pregnancies, specialized interpretation may be required.
Important Information
The Second Trimester Quadruple Test is a screening test, not a diagnostic test. An abnormal or higher-chance result does not mean that your baby definitely has a chromosomal condition or birth defect.
- The test estimates risk and does not provide a definitive diagnosis.
- False-positive and false-negative results can occur.
- An incorrect gestational age can affect the interpretation of the results.
- Multiple pregnancy can affect marker levels and requires appropriate interpretation.
- An abnormal result may lead to a detailed ultrasound, genetic counselling, additional screening or diagnostic testing.
- Diagnostic testing such as amniocentesis may be discussed when clinically appropriate.