Quadruple screening test

The quadruple screening test is offered to pregnant women in the second trimester (from 14 to 20 weeks’ gestation). Quadruple screening assesses the chance of a pregnancy being affected with Down syndrome. It does not screen for Edwards syndrome or Patau syndrome.

Quadruple screening is usually offered when combined screening cannot be offered because:

• the woman presents later than expected to maternity services;
• the measurement of nuchal translucency cannot be obtained; and
• the fetal crown-rump length measurement is found to be greater than 84 millimetres and the head circumference measurement is between 101 millimetres and 172 millimetres during ultrasound examination.

Four biochemical markers are analysed and combined with maternal age to generate a quadruple screening test result. These comprise:

• alpha-fetoprotein (AFP);
• human chorionic gonadotropin (hCG) or free bhCG;
• inhibin A; and
• unconjugated oestriol (uE3).

A maternal venous blood sample is required for analysis, as well as an accurate measurement of the fetal head circumference. The measurement must be recorded on the test form that goes with the sample to the biochemistry laboratory.

If the screening returns a low-chance result for Down syndrome, no further action is required.

Where a higher-chance result is given (over 1-in-150), further assessment should be offered. This may include further ultrasound imaging in a specialist fetal medicine unit, non-invasive prenatal testing or diagnostic testing requiring chorionic villus sampling or amniocentesis.

For further information, see Presentation: Patient with a higher-chance first-trimester combined screening result.

For clinicians

• Improving News Delivery in Ultrasound: Consensus guidelines on the communication of unexpected news via ultrasound (PDF, 44 pages)
• NHS England: National Genomic Test Directory

For patients

• Antenatal Results and Choices
• Down’s Syndrome Association