Obstetric Ultrasounds

The Viability Ultrasound is usually performed at around 6-11 weeks that is after at least 10-15 days of a delayed menstrual cycle.

This test determines whether the pregnancy is intrauterine and the heartbeats of the fetus can be heard for the first time.

Simultaneously, the uterus can be examined for possible uterine fibroids and potential ovarian cysts.

The ultrasound scan at 11-14 weeks consists the first detailed examination of the fetus and allows the calculation of the probability of chromosomal abnormalities, of which one of the most common is Down's syndrome or mongolism. Children with Down’s syndrome always have to some degree mental retardation while often have heart problems. Any woman can give birth to a child with Down’s syndrome, but the probability increases with increasing age.

The only way to be certain that the fetus has not gotten Down’s syndrome is by an intervention (amniocentesis or chorionic villus sampling), which examines the genetic material from the amniotic fluid (amniocentesis) or the placenta (chorionic villus sampling) that is identical to the genetic material (chromosomes) of the embryo.

However, these interventions have a small percentage of miscarriage (about 1%). For this reason, the decision whether or not to proceed to such an intervention is best based on a test that calculates the probability of the fetus having Down’s syndrome. This test is the ultrasound examination at 11-14 weeks where the measurement of nuchal translucency is performed and the presence of the nasal bone (the bone in the nose of the fetus) is evaluated. These findings are combined with the measurement of two hormones in the blood of the mother (PAPP-A, b-hCG). The nuchal translucency is a liquid found in the fetal neck, underneath the skin. All embryos have this fluid, but those suffering from Down’s syndrome usually have more liquid. During the ultrasound scan performed at 11-14 weeks the growth and the major organs of the fetus are also being monitored. By measuring the nuchal translucency, nasal bone and the two hormones in the mother's blood, we can predict at least 9 in 10 children suffering from Down’ Syndrome (95% sensitivity).

The result that you will eventually get is a number that represents your personal chance of having a baby with Down’s syndrome. The result is based upon your age, your medical history (it is important to state whether you had previous pregnancies with a similar problem or have a family history), the fetal measurement and the hormones in your blood. For example, if your score indicates probability 1:2000, this means that if we had 2000 women like you, one would have a fetus with Down’s syndrome and the rest 1999 would have had normal embryos. The examination at 11-14 weeks can never assure you that the fetus has not gotten Down’s syndrome.

This method of calculating the probability of Down’s syndrome is very precise and its results have been confirmed in hundreds of thousands of women worldwide. In addition, the department of Ultrasonography and Embryo-Maternal Medicine of LETO Maternity Hospital is staffed by physicians who have the necessary certificates of competence from the Fetal Medicine Foundation (FMF, www.fetalmedicine.com) in London which developed this method. FMF verify the results of all internationally recognized centres in order to maintain the same high level.

The results of the ultrasound and biochemical testings will show low risk for Down’s syndrome (i.e. probability of less than 1:300) in most women.

If your score indicates greater likelihood than 1:300, it means that you should consult your doctor and together decide whether to proceed surgically (amniocentesis or chorionic villus sampling) to check with certainty the chromosomes of the fetus. Even in high-risk groups most embryos are in the end normal.

Thus, for example if the fetus has a probability of 1:100 of Down’s syndrome, this means that out of 100 pregnancies only one would result in a problematic fetus, while the remaining 99 would be normal.

The fetuses with increased nuchal translucency and normal chromosomes are usually normal. However, they have greater probability for congenital abnormalities of various organs especially heart disease and some rare diseases (genetic syndromes). Many of these problems can be screened with detailed ultrasounographic imaging and that is why those embryos require more specialized testing.

With this ultrasound the gestational age is calculated with precision, which is especially important to women with unstable menstrual cycles. In multiple pregnancies, the chorionicity is estimated, i.e. whether the fetuses have separate placentas or a common placenta, information which determines the course of the pregnancy and how to monitor it. Finally, this ultrasound scan offers the possibility of a first rough estimation of fetal anatomy as to be able to detect a significant proportion of serious abnormalities at this early stage.

The B-level Ultrasound scan is performed at 20-23 weeks and includes a series of measurements to control the development and calculation of fetal weight, placental control, assessment of amniotic fluid and detailed inspection of the fetal organs for congenital abnormalities. The cranium, brain, face, spine, thorax, heart, abdomen, kidneys, bladder, arms and legs are examined. About 70% of serious birth defecits can be detected with the help of this detailed ultrasound scan. Unfortunately, no ultrasound scan, no matter how detailed and comprehensive, can eliminate the entirety of abnormalities or guarantee the birth of a normal healthy child.

The B-level Ultrasound scan also includes screening for markers (signs) of chromosomal abnormalities, such as Down’s syndrome. In this way the B-level ultrasound scan complements the ultrasound scan of 11-14 weeks in the final assessment of the likelihood of Down’s syndrome.

It is a very detailed ultrasound which controlled the anatomy and function of the fetal heart and the blood flow in the heart and great vessels. It is made by Pediatric cardiologist specializing in prenatal testing. Usually recommended in cases with a family history of heart defects in mothers with specific health problems (such as diabetes) and in pregnancies in which suspected abnormality of the normal control.

The ultrasound is usually done after 18 weeks although in recent years attempting to control what is done earlier. The Technology and expertise to have possibility of early fetal heart monitoring from 12 weeks where there is similar wording.

With the colour Doppler ultrasound the blood flow in the uterine arteries is monitored. If the resistance in the uterine arteries is high the likelihood of the mother developing pre-eclampsia or the fetus having little weight increases. Approximately one in four women with increased resistance will have such problems, while in the rest of the female population the pregnancy will develop normally. If during the B level ultrasound scan increased resistance is found close monitoring of the pregnant woman’s blood pressure and monthly ultrasound scans of the fetus are recommended.

Finally in the B-level ultrasound the length of the cervix is being measured. The cervix is the lower part of the uterus that opens up (expands) in childbirth. The measurement is done reliably by trans-vaginal ultrasound. If the cervix is significantly smaller (less than 15mm), the risk of premature birth increases. Recent studies have shown that by providing better treatment to women with short cervixes, the incidence of extremely premature birth is reduced by 40%.

The growth ultrasound scan is performed starting at 24 weeks until the end of pregnancy, depending on the physician’s advice. Fetal growth, weight, quantity of amniotic fluid, the location of the placenta are being monitored. The Doppler examination is the control of the blood flow of the embryo’s vessels and placenta (usually the flow in the umbilical artery and the middle cerebral artery is examined), which gives us information on the functioning of the placenta and the status of the fetus. This information is particularly important for small weight fetuses and helps us decide whether an underweight (small for gestational weeks) fetus receives enough oxygen and nutrients from the placenta. In cases where the flow in these vessels is not normal more detailed and frequent monitoring is required.

Technology now allows us to have three-dimensional imaging of the fetus. The three-dimensional image (3D) occurs from the composition of many two-dimensional images. In the more sophisticated devices the fetus can be seen three-dimensionally in real time (4D), i.e. to see his/her movements.

The usual two-dimensional ultrasonographic image gives us the most important information about the fetus. In some rare abnormalities the three-dimensional ultrasound scan can help us see certain organs better, however, the two-dimensional ultrasound basically guides us in our diagnosis.

The biggest advantage of three-dimensional ultrasonography is that it gives us the satisfaction to see ‘truer’ images of the fetus in his/her natural environment.