Early Pregnancy Viability Scan or Dating Scan

Viability scans are performed at 7-11 weeks of pregnancy. Dr Georgiou will usually scan ‘transabdominally’; through your tummy. If there is a concern about a possible ectopic pregnancy, this scan can be done at 6-7 weeks trans-vaginally. At this stage it is unlikely to see a heart beating but it is possible to confirm that the pregnancy sac is in the uterus. The scan at 7-11 weeks can show how many embryos there are, confirm the presence of a heartbeat and confirm the number of weeks of your pregnancy. This scan is also called a Dating Scan.

Nuchal Translucency Scan

This is the first stage at which the fetus can be seen in greater detail. This scan confirms that there is a heartbeat, and the number of fetuses. It is important this scan to be performed by a specialist Fetal Medicine Consultant. Baby’s head, trunk, arms, legs, hands and feet can be seen and they will also look at the placenta, amniotic fluid and umbilical cord. They will then measure the ‘nuchal fold’ or ‘nuchal translucency’ and the baby’s nose bone. The nuchal translucency is the skin at the back of the baby’s neck. In some babies with problems such as Down’s syndrome, and also in some normal babies, this can be enlarged by fluid. The nose bone can be small or absent in Down’s syndrome babies. We will need a blood sample from your arm and perform a blood test for two specific hormones. The result of this test  will give you specific information about your level of risk of your baby having fetal abnormalities such as Down’s syndrome. This is called the combined test for Down’s Syndrome.

Reassurance Scan at 14 weeks – 22 weeks

A scan is not usually necessary at this stage of your pregnancy, though it may be required if you have had bleeding or been unwell. It measures baby’s head, abdomen, and leg length and locates the placenta, the amniotic fluid and assesses the umbilical cord. The measurements will be plotted on a graph for you.

Sexing Scan at 17-23 weeks

At this stage you can usually discover the sex of your baby with very reliable sexing. Dr Georgiou will only advise you of your baby’s sex if you ask. She will also measure your baby and assess its well-being.

Anomaly Scan at 21 weeks – 23 weeks

A specialist Fetal Medicine Consultant will take measurements of your baby’s head, brain, abdomen and legs and plot them on a chart. They will then perform a detailed scan to check your baby’s heart, brain, spine, bowel and limbs, to detect any abnormalities. This can never completely rule out any abnormalities, but it does give very strong reassurance. They will also scan the placenta, amniotic fluid and the umbilical cord. If you wish, you can find out the sex of your baby from this scan.

Cervical Length Scan

If your baby is at risk of premature birth, it may be useful to have a scan, using a probe in the vagina, to assess the length of the uterine cervix. This can be done at any stage from 16 weeks but is most useful if done sequentially at 17 and 21 weeks of pregnancy.

During these scans (also callled growth scans) Dr Georgiou measures the baby’s head, abdomen and limbs, and estimate it’s weight. This gives a guide to how big your baby will be at birth. She also looks at how the baby is moving, the amount of amniotic fluid, where the placenta is, as well as assessing the Doppler blood flow in the umbilical cord blood vessels.

It has been discovered that a blood sample taken from the mother at any time from early pregnancy can be analysed for cell free fetal DNA, which is essentially a marker in the mother’s blood of the DNA of the baby. The result of the simple blood test (Harmony), taken at 10 weeks or later has a sensitivity for the detection o fa chromosomal abnormality in a pregnancy (Down’s syndrome detection greater than 99%). This can reduce the need for invasive testing by CVS or amniocentesis. This is great news for couples because it eliminates the risk of miscarriage from invasive testing. It is important that an ultrasound scan is performed just before the blood test to confirm the pregnancy, and to check that the mother is not carrying twins or more. The Harmony test can be used to check twins with a sensitivity for the detection of Down’s syndrome greater than 95% and can now be used if the pregnancy is conceived with donated egg.

Who needs a Harmony Test?

Anyone who wants extra reassurance about the normality of the pregnancy can have the test. Women who may need it are those who are anxious about their baby having a chromosomal abnormality such as Down’s, Edwards or Patau’s syndrome, older women (particularly over 40 years) and those who have already had a chromosomally abnormal pregnancy often opt for the test. Those who are at particular risk of miscarriage should they have an amniocentesis or chorionic villous sample also find the test very attractive as it avoids an invasive procedure. It is helpful for those who have had a previous sex chromosome abnormality such as Turners syndrome.

How is the result expressed?

The result is expressed as a probability. It is a screening test and not a diagnostic test. A result form of a low risk test is shown below. A low risk test result gives a risk of a chromosomal problem of less than 1:10000. A high risk result gives a risk of greater than 99%. A high risk result does not confirm that the baby has the chromosome abnormality. An amniocentesis or chorionic villous sampling is necessary to give a diagnosis. The couple are counselled about this.

Are there some abnormalities the Harmony test will not detect?

Yes. Structural abnormalities such as Spina Bifida, heart defects and a poorly growing baby will only be seen on scans and often not until later scans. These scans should still be undertaken.