Fetal Anomaly Screening Programme
NHS England Screening NHS Fetal Anomaly Screening Programme (FASP)
NICE guideline [NG201] Antenatal care. Aug 2021.
Changes were made to the quadruple test:
- The NHS Fetal Anomaly Screening Programme previously only offered the quadruple test for Down syndrome; a recommendation to include Edwards’ syndrome was approved by the government in December 2025
- In short, the quadruple test is now used to screen BOTH Down syndrome and Edward’s syndrome
Date: 31/03/26
There are 2 main screening pathways:
- Combined test and/or quadruple test – for trisomy 21, 18, 13
- 20-week anomaly scan – for 11 physical conditions
- Offered 18+0 – 20+6 weeks
Trisomy 21, 18, 13 Screening Pathway
Approach:
- First, perform screening tests (these test simply gives a result of higher or lower chance)
- If the screening test result is higher chance → 2nd line tests
Step 1: Screening Tests
There are 2 main screening tests:
| Screening test | Indications |
|---|---|
| Combined test (1st line) | Most common screening test, used for most patients who follow the routine antenatal care pathway
Performed between 10-14 weeks |
| Quadruple test | Performed between 14-20 weeks
Indicated if the combined test is NOT appropriate:
|
Interpretation and subsequent actions (based on combined and/or quadruple tests):
- Lower chance → reassure and no further tests
- Higher chance → proceed to 2nd line tests
Combined Test Component and Interpretation
The combined test can screen for trisomy 21, 18, 13 (Down, Edward, Patau syndrome)
The combined test involves assessing:
- Maternal age
- Biochemical marker – free β-hCG and PAPP-A
- Nuchal translucency
Trend interpretation:
| Condition | Nuchal translucency | β-hCG | PAPP-A |
|---|---|---|---|
| Down syndrome (trisomy 21)* | ↑ (≥3.5 mm) | ↑ | ↓ |
| Edwards syndrome (trisomy 18) | ↑ | ↓ | ↓ |
| Patau syndrome (trisomy 13) | ↑ | ↓ | ↓ |
*Most likely to be examined.
Quadruple Test Component and Interpretation
The NHS Fetal Anomaly Screening Programme previously only offered the quadruple test for Down syndrome.
However, a recommendation to include Edwards syndrome was approved by the government in December 2025. [Ref]
The quadruple test only assesses the chance of the baby having trisomy 21 (Down syndrome) and trisomy 21 (Edwards syndrome)
The quadruple test involves assessing 4 biochemical markers:
| Condition | β-hCG | Inhibin-A | AFP | Unconjugated oestriol |
|---|---|---|---|---|
| Down syndrome (trisomy 21) | ↑ | ↑ | ↓ | ↓ |
| Edward syndrome (trisomy 18) | ↓ | Normal | ↓ | ↓ |
Step 2: NIPT or Confirmatory Test
For those with a higher chance result (from the screening test), offer the women a choice of:
- Non-invasive prenatal testing (NIPT), or
- Confirmatory tests (invasive prenatal diagnosis)
NIPT (Non-Invasive Prenatal Testing)
| Timing | ≤ 21+6 weeks (first sample) |
| Description | Maternal blood test to analyse cffDNA that circulates in the maternal circulation |
| Interpretation and subsequent actions | NIPT results are reported as lower chance or higher chance
Subsequent action:
|
NIPT is still a screening test, it is more sensitive than the combined and quadruple test, but NOT a diagnostic test.
The only diagnostic tests are chorionic villus sampling or amniocentesis for chromosomal or genetic analysis.
Confirmatory Tests (Invasive Prenatal Diagnosis)
There are 2 confirmatory tests that allow prenatal diagnosis of trisomies 21, 18 and 13:
- Chorionic villus sampling
- Amniocentesis
| Test | Gestational age* | Description |
|---|---|---|
| Chorionic villus sampling | 11-14 weeks | Ultrasound-guided transabdominal / transcervical procedure to obtain a sample of placental tissue for chromosomal or genetic analysis |
| Amniocentesis | 15-20 weeks | Ultrasound-guided extraction of amniotic fluid for chromosomal or genetic analysis |
*Gestational age at the time of referral is a key determinant in selecting the appropriate confirmatory test
NHS England: One in 200 women who have a CVS or amniocentesis will miscarry.
20-week Anomaly Screening Pathway
The 20-week screening scan is also known as the anomaly scan:
- Timing: 18+0 – 20+6 weeks
- Description: ultrasound scan to screen for 11 physical conditions
If the scan detected / raised suspicion of physical conditions:
- Refer, and
- Offer confirmatory testing (chorionic villus sampling or amniocentesis), and
- Discuss options of continuing pregnancy vs terminating pregnancy
11 Physical Conditions
- Trisomy 18 and 13 (Edward’s and Patau’s syndrome)
- 2 neural tube defects (anencephaly and spina bifida)
- 3 GI defect (cleft lip, gastroschisis, exomphalos)
- Congenital diaphragmatic hernia
- Congenital heart disease
- Bilateral renal agenesis
- Severe skeletal dysplasia
References