Step 1: Book for antenatal care as soon as possible.

Some tests can only be done very early in the pregnancy. Others may have to be booked many weeks in advance as appointments may be difficult to come by! 

Step 2: Read the “Prenatal tests leaflet” on the SASUOG or SASOG website.

It gives a clear overview of all the available tests and of the very important decisions you will need to make. Please take the time to read it carefully. Discuss it with others if you prefer, so you can start forming an opinion on what is important to you. It may also be helpful to find out ahead of time which tests are covered by your medical scheme as some can be quite pricey. 

Step 3: Attend the first visit together with your partner or another supportive person, if possible.

At the end of this visit, you will make important and possibly life changing decisions. Having your partner with you or someone who knows you well will help to make sure you really understand the differences between the available tests. You can also use this chance to ask all the questions you need to clarify your thoughts before you decide what to do. 

Please take a printed copy of the leaflet along. It can function as a discussion document to help you communicate to your practitioner which test or combination of tests you would prefer, if any. 

It is very important that you disclose ANY risk factors that increase the chance that there may be something wrong with your baby. The best choice of test often depends largely on those risk factors. 

Step 4: Understand that you will ultimately need to balance two risks against each other.

When you are expecting a baby, there is always risk involved. With screening choices, the risk on the one side is of having a child with health or developmental problems and special needs. This can happen if you opt against the best available test, because then you may only find out there is something wrong after the baby is born. On the other hand, some tests are very expensive or may involve a risk of complications, even miscarriage. You might therefore lose the baby as a result of the test you had to rule out any problems. We know it is unpleasant to have to choose between these two risks. Unfortunately, there is never a no-risk situation once you have fallen pregnant…. 

As the main concerns are the possibility of a genetic condition (Down syndrome being the most common) and structural defects of the fetal body parts…. 

What would be a good approach if there were no specific risk factors for your pregnancy?

1. Book early so your practitioner can do a very early scan to date the pregnancy. All tests can then be scheduled at the right time and be interpreted correctly.

2. Consider a blood test for Down syndrome screening at 9 weeks (possible up to 13 weeks).

3. Consider a blood test for Down syndrome and neural tube defects (NTD) at 15-16 weeks (possible up to 20 weeks).

4. Arrange a scan at 12 weeks and another one at 20 weeks to assess the fetal development.

5. If the results of any blood test indicates a risk for Down syndrome higher than what you are comfortable with, you can request further tests. These tests include either NIPT (Non-Invasive Prenatal Testing, a test to check the baby’s DNA in a blood sample of you) or referral to an expert for in-depth ultrasound assessment or possible invasive testing.

6. If the result indicates an increased risk for NTD (open spina bifida), referral to an ultrasound expert is the best way to check whether the baby has any visible physical abnormality or not.

7. If your regular obstetric practitioner performs your scans and is unhappy with any images during the ultrasound assessment, referral to a fetal medicine expert is recommended for in-depth assessment and counselling.

What if there are risk factors for your pregnancy or you will worry too much unless you have had the best tests possible? 

In that case, we suggest the blood test at 9 weeks and NIPT at 10-12 weeks, while arranging both your scans with an expert. This will require booking many weeks in advance as most experts are not available at short notice. It may require significant travel as most experts work in the metropole areas only and will certainly incur significant cost. If you feel you need this to be maximally reassured however, then perhaps this is worth it for you. 

Keep in mind that even a series of excellent tests will still not provide a 100% guarantee that your baby will be perfectly healthy and perfectly formed. Many significant conditions (incl. autism, mental disability, most rare genetic diseases and even many structural defects in different body parts) are simply NOT detectable before the baby is born….. Some small risk is therefore always going to remain. 

Also, remember that, if you do not have specific risk factors, even without any test, the chances are more than 95% of having a normal baby! 

We wish you all the best with your decisions!!!

The SASUOG team

Amniocentesis involves the examination of cells in the fluid from around the fetus (amniotic fluid).

The cells in the amniotic fluid originate from the baby and so the chromosomes present in these cells are the same as those of the baby.

How is amniocentesis done?

Amniocentesis involves passing a thin needle into the uterus in order to remove a small volume of amniotic fluid. The needle is carefully observed using ultrasound scan.

The fluid is fetal urine and the amount removed by amniocentesis reaccumulates within a few hours.

The procedure lasts 1 minute and afterwards we check that the fetal heart beat is normal.

What should I expect after amniocentesis?

For the first couple of days you may experience some abdominal discomfort or period-like pain. You may find it helpful to take simple painkillers like paracetamol.

If there is a lot of pain, bleeding, loss of fluid from your vagina or if you develop a temperature please seek medical advice.

When can I expect to get the results?

The rapid results for Down’s syndrome and other major chromosomal defects are usually available within 3 days (FISH or PCR). The results for rare defects and the full culture can take 2 weeks. As soon as we get the results, we will call you to let you know.

What are the risks associated with amniocentesis?

The risk of miscarriage due to amniocentesis is about 0.6% and this is the same as the risk from chorion villus sampling. If you were to miscarry due to the test, this would usually happen within the next five days.

Some studies have shown that when amniocentesis is performed before 16 weeks there is a small risk of the baby developing club feet. To avoid this risk we never perform amniocentesis before 16 weeks.

Chorion Villus Sampling (CVS) involves the examination of chorionic villi (placental tissue). Both the baby and placenta (afterbirth) originate from the same cell and so the chromosomes present in the cells of the placenta are the same as those of the baby. 

How is CVS done? 

Local anaesthetic is given. A fine needle is then passed through the mother’s abdomen and a sample of villi is taken. The needle is carefully observed using ultrasound scan. The procedure lasts 1-2 minutes and afterwards we check that the fetal heart beat is normal. 

What should I expect after the CVS?

For the first couple of days you may experience some abdominal discomfort, period-like pain or a little bleeding. These are relatively common and in the vast majority of cases the pregnancy continues without any problems. You may find it helpful to take simple painkillers like paracetamol. If there is a lot of pain or bleeding or if you develop a temperature please seek medical advice. 

When can I expect to get the results?

The rapid results for Downs Syndrome and other major chromosomal defects are usually available within 3 days (FISH or PCR). The results for rare defects or the full culture can take 3 weeks. As soon as we get the results, we will call you to let you know. 

Will the procedure need to be repeated?

In approximately 1% of cases the invasive test may need to be repeated because the results are inconclusive. 

What are the risks associated with the test? 

The risk of miscarriage due to CVS is about 0.6% and this is the same as the risk from amniocentesis at 16 weeks. If you were to miscarry due to the test, this would happen within the next five days. Some studies have shown that when CVS is performed before 10 weeks there is a small risk of abnormality in the baby’s fingers and/or toes. To avoid this risk we never perform CVS before 11 weeks.

ACCURACY OF FETAL GENDER DETERMINATION BY ULTRASOUND

Fetal gender (fetal sex) is determined on ultrasound by looking at the genitalia. Sonologists can never be 100% certain of gender. Too be absolutely certain of gender, fetal genetic material would need to be sampled. Certain maternal factors, such as abdominal adipose or scar tissue can inhibit views as well as fetal factors such as the position of the fetus affect how well the genitalia can be seen.

First Trimester (up until 13 weeks):

This is performed by looking at which direction the genital tubercle faces (upwards or downwards) in a longitudinal view of the fetus.

Accuracy: If the genital tubercle can be seen, the fetal gender is accurate in approximately 90% of the time. However, the tubercle cannot be seen in up to 25% of cases due to maternal or fetal factors (Gharenkhanloo 2018). Accuracy is improved as gestation increases (i.e it is more difficult to determine gender at 11 weeks than at 13 weeks).

Second Trimester (14 – 28 weeks)

This is performed by looking between the baby’s legs and views can be limited if the baby lies with its legs closed during the sonar or if there is not much amniotic fluid (water) around the baby.

Accuracy: In the 1990’s, accuracy was around 92%, being slightly higher in males than female fetuses (Watson WJ). By 2014, accuracy had improved to 99.5% (Kearin M. 2014). Accuracy will depend on the type of ultrasound machine used as well as the skill of the operator. The 2^nd trimester is the best time to view the genitalia.

Third Trimester (29 weeks – term):

It can often be difficult to see the genitalia in the 3^rd trimester as there is less space in the womb for the baby to open its legs. If the genitalia can be clearly seen, this scan can be quite accurate for determining fetal gender, however, due to difficulties obtaining good views, it is often not possible to comment on gender in the later stages of pregnancy.

If the genitalia can be seen, the accuracy can be up to 99% (Kearin 2014). This again, depends on the quality of the ultrasound machine used, the experience of the operator as well as maternal and fetal factors.

Compiled by Dr Zoe Momberg