Neonatal Medicine - Screening in Pregnancy

**Down's Syndrome**
The optimal time for screening is between 11+0 weeks to 14+1 weeks gestation using the 'Combined Test' : ultrasound Nuchal Translucency (NT) measurement (the thickness at the back of the baby's neck), plus serum biochemistry testing to measure free beta hCG and PAPP-A.

It will give a mother's risk of having an infant with Down's Syndrome compared to the initial background risk (based on her age). Actual diagnosis requires Chorionic Villous Sampling (CVS) or amniocentesis, although non-invasive testing is becoming possible utilising free fetal DNA.

**Fetal Anomaly Screening**
The second ultrasound scan in the pregnancy is often called a Mid-Trimester Anomaly scan and happens between 18-21 weeks . It screens for major structural anomalies including some cardiac complaints, limb abormalities, cleft lip (but not palate), renal abnormalities (e.g. hydronephrosis) and intestinal problems.

The Anomaly scan is now the preferred time to look for Neural Tube defects (such as Anencephaly and Spina Bifida) and Trisomy 13 and 18.

It is important to note that not all abnormalities can be seen on an ultrasound scan.

Maternal Blood Tests

All pregnant women are offered screening for four infections: hepatitis B, HIV, syphilis and susceptibility to rubella.

Women with hepatitis B, HIV or syphilis are offered care and treatment to reduce the risk of passing the infection to their baby, and for their own health and wellbeing.

Women who are not protected against rubella (called rubella susceptible) are offered vaccination to protect future pregnancies.

Women will also have their blood group tested to see if there is a risk of Rh-incompatability if mother is Rh-negative; in the event of sensitisation events such as a bleed or the delivery itself the mother should be give Anti-D (RHO) immunoglobulin to prevent her producing antibodies against a Rh-positive fetus.