The quadruple screening test, also known as the quad screen, AFP Plus quad test or multiple marker screening test, is a maternal antenatal screening blood test that can be used in conjunction with other investigations e.g. ultrasound soft markers, to estimate the risk of aneuploidy 1.
This is especially valuable when no first-trimester screening is available. It has been proved as a feasible and efficient non-invasive method for screening for Down syndrome. It is usually used before more invasive tests such as amniocentesis 2.
Temporal window: fetal age 17-20 ± 2 weeks.
It tests for the three substrates of the triple test (alpha-fetoprotein, beta human chorionic gonadotropin, unconjugated oestriol) plus inhibin-A.
As with the triple test, it helps counsel patients for high-risk pregnancy and progressive assessment for the validity of other ultrasound soft markers 3.