Dr. Shanthi Sairam
Consultant Obstetrics and Gynaecology – A UK-trained Obstetrician with a special interest in Fetal Medicine and Fetal Cardiology
Pregnancy is a journey of the baby’s growth and development, and every mother main concern during pregnancy is making sure their child is developing and growing normally. In order to check that the pregnancy is a healthy, and normal one and that the mother and baby are healthy the pregnant woman undergoes a series of scans throughout the pregnancy, among them is the scan performed between the 11th and 14th week of the pregnancy.
This is a routine scan that is recommended for all pregnant women. It helps to establish the viability of the pregnancy and the accurate dates of pregnancy, giving an estimated date of delivery. It also identifies multiple pregnancies and some structural anomalies in the baby. The 11-14 week scan provides an opportunity to screen for chromosomal abnormalities (such as Downs Syndrome) by measuring the nuchal translucency (the fluid behind the baby’s neck). This measurement is combined with results of the blood test to give a risk assessment for Down’s syndrome.
This scan is usually performed from 11+0 to 13+6 weeks, and does not require a full bladder for imaging. With advances in ultrasound technology, successful anatomical assessment of the first trimester fetus is becoming possible. Several structural anomalies are being increasingly diagnosed during this scan. The extent of assessment depends significantly on the quality of the images obtained. This in turn depends on the position of the baby and how easily ultrasound waves are allowed through the maternal tissues.
With the introduction of the non-invasive prenatal tests for Down’s Syndrome screening, the role of this scan is currently being questioned. However, I would like to strongly recommend that pregnant women have this scan regardless of their choice test for Down’s Syndrome screening. This scan can identify issues, if any, that can significantly influence the management options in the pregnancy.
In particular, this is an important scan for multiple pregnancies as it allows the determination of Chorionicity. It can recognize whether the fetuses are sharing a placenta reliably at this gestational age. As the pregnancy progresses, the reliability of this assessment decreases due to the changes in the placental appearance. Chorionicity determines the chances of complications that are particularly unique to twin pregnancies.
All pregnant women, are encouraged to talk to their doctor and get the sound advice about the necessary scans and test to assess that baby’s wellbeing and the overall state of the pregnancy.