Approximately 5 percent of IVF pregnancies will result in an ectopic pregnancy, ie where the pregnancy implants outside the uterine cavity. These pregnancies are non-viable and may cause internal bleeding. Because of this risk an early diagnosis and early treatment is important and for this reason all patients are referred for an ultrasound examination following transfer to assess the site of pregnancy implantation.

A pregnancy test is routinely performed on day 16 following transfer. If this is positive a transvaginal ultrasound is arranged, usually for 4 weeks following transfer. The site , number and viability of the gestation(s) is / are documented.

At 6 weeks gestation (about 4 weeks following transfer) a pregnancy sac, a yolk sac, an embryo and embryonic heart motion should be visible. Delay in the appearance of these individual structures may be an indicator of subsequent miscarriage.

Miscarriage occurs in 15-20% of IVF pregnancies and the diagnosis is usually made upon inappropriately low hormone levels in association with poor prognostic markers noted on ultrasound. In many patients where signs of pregnancy failure are present a repeat ultrasound examination is necessary before a firm diagnosis of miscarriage can be made.

Why have a scan at 11-14 weeks?

Nuchal Translucency:
Currently the most accurate non invasive test for detecting Down syndrome during pregnancy is the measurement of the nuchal translucency with ultrasound between 11-14 weeks of pregnancy. This is normally less than 2.5mm and when increased (ie>2.5mm) may indicate the baby has Down syndrome or another chromosomal abnormality.

What is the Nuchal Translucency?
The nuchal translucency is a collection of fluid beneath the fetal skin in the region of the fetal neck and is present in all fetuses in early pregnancy. The fluid collection is however increased in many fetuses with Down syndrome and many other chromosomal abnormalities. It is called a "translucency" because on ultrasound it appears as a black space beneath the fetal skin. It is this black space that you will see measured during the ultrasound scan.

If the Nuchal Translucency is increased what happens next? If the nuchal translucency is increased then you will be offered a needle test which is called chorionic villus sampling or C.V.S. (ref CVS information leaflet). This test involves taking a biopsy from the placenta and examining the baby's chromosomes. In these circumstances an urgent report is requested (short term culture) and if sufficient cells are present in the sample the results may be processed as early as 2-3 days. The complete analysis (long term culture) takes 2-3 weeks.The normal short term culture excludes major chromosomal problems such as Down Syndrome and the long term looks at the chromosomes in greater detail thus excluding more subtle chromosomal abnormalities.

How is the scan performed?
We generally recommend that the scan be performed through the vagina (ref. transvaginal information leaflet). In these circumstances a very narrow ultrasound probe is gently placed a short distance into the vagina and the ultrasound beam directed towards the baby. With this approach greater detail is obtained of the fetal anatomy. However if you wish to have an ultrasound examination through the lower abdomen this can be arranged.

What happens if the chromosome test (CVS) is normal?
For patients where there was an increased nuchal translucency and later a normal CVS result, there is still a slight increased risk of a structural abnormality in the baby (6%, compared to the background risk of 2-3%); eg a congenital heart defect. For this reason a detailed examination of the fetal anatomy is required around 18-20 weeks.For most patients the anatomy is normal and the pregnancy progresses uneventfully.

What happens to the increased nuchal translucency with advancing pregnancy?
In the majority of patients this disappears and is not visible at the routine 18-20 week ultrasound. This explains why it is important that the scan be performed around 11-14 weeks. ie there is only a narrow window of opportunity when this ultrasound marker of chromosomal abnormality is evident.

What is the risk of the scan?
A transvaginal and transabdominal ultrasound examination is a safe investigation at all stages of pregnancy.

What else can the 11-14 week ultrasound scan show?
A scan at 11-14 weeks provides an opportunity to assess the anatomy of the baby. At this early stage of pregnancy it is now possible to determine many structural abnormalities previously only visible at 18-20 weeks. During the examination many parts the fetal anatomy will be pointed out to you. It is also an opportunity to determine the number of babies present and the baby's heart rate.

Normal Nuchal Translucency

This image shows a longitudinal section through a fetus with the head to the left and the legs to the right. The arrows point to the tiny collection of fluid beneath the fetal skin, ie. The Nuchal Translucency which in this baby is normal.

Increased Nuchal Translucency

This image shows a longitudinal section through a fetus at 11 weeks. The head is the left and the legs to the right. The arrows point to the increased Nuchal Translucency. Placental biopsy (CVS) in this fetus revealed Down Syndrome.

What is the combined test?
This test has recently become available in Victoria. It is a screening test which combines the results of two proteins in the mothers blood with ultrasound to determine your risk of having a baby with Down syndrome and other chromosomal abnormalities. The accuracy of detecting Down Syndrome is approximately 85-90%. The advantage of this test over others is that a result is obtained early in pregnancy, around 11-14 weeks.

How is the test performed?
Blood is taken from your arm at approximately 10 weeks gestation. This should be arranged through your nearest approved pathology collection service as advised by your doctor. The blood is then dispatched to the Murdoch institute at the Royal Children's Hospital, in Parkville. Two blood proteins (PAPP-A and beta-HCG) are measured. Approximately 2 weeks later when the pregnancy is around 12 weeks an ultrasound scan is performed. At this examination the fetal development, size, and nuchal translucency are documented (refer Nuchal Translucency leaflet). The nuchal translucency result is faxed to the Murdoch Institute and the results of the blood test and ultrasound are combined to give one result. You will be given the results soon after the ultrasound examination.

How should I interpret the results?
Your results will be given to you as a risk estimate; i.e. the chance of your baby having Down syndrome. For example if you are 28 years old your chance of having a baby with Down syndrome is about 1 in 600. But if you