Obstetrics• Updated 21 October 2026
Quadruple Marker Test
A second-trimester blood test that estimates the chance of Down syndrome and neural tube defects.
Results: A few days Specimen: Blood
Quick Summary
Primary Purpose
To screen for chromosomal conditions and spine defects between 15 and 20 weeks.
What It Measures
AFP, hCG, oestriol and inhibin A.
Preparation
No preparation.
Overview
Used when first-trimester screening was missed.
It's a screening test with false positives.
What It Measures
Four markers
Combined risk.
How It's Performed
- 01
Timing
15–20 weeks.
- 02
Blood sample
From a vein.
- 03
Result
Risk estimate.
Interpreting Results & Next Steps
Discuss with Doctor
Your doctor will explain what your result means and what happens next.
If values are High:
A higher-chance result leads to further tests.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Down Syndrome Tests(opens in a new tab) · MedlinePlus, US National Library of Medicine