Fetal Medicine
Fetal medicine includes the assessment of fetal growth and wellbeing, the maintenance of fetal health, the diagnosis of fetal illnesses and abnormalities and treatment of the “unborn patient”. Our capability to diagnose problems before birth has improved through state-of-the-art prenatal diagnosis techniques giving patients better chance of wellbeing. Our ultrasound scans are performed to the highest standards and are backed up with informative and sensitive counseling by maternal-foetal medicine specialists and geneticists.
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When a nuchal translucency screening is done?
NT screening must be performed between 11 and 13 weeks of pregnancy. After that, the tissue gets so thick that it’s no longer translucent, making test results inconclusive.
What does nuchal translucency measure?
NT focuses on a small, clear space at the back of a growing baby’s neck called the nuchal fold. Experts have found that this spot tends to accumulate fluid and, as a result, expands in size in babies who have genetic abnormalities like Down syndrome (caused by an extra copy of chromosome 21, one of the 23 pairs of chromosomes that contain a person’s genetic code), trisomy 18 (an extra copy of chromosome 18) and trisomy 13 (an extra number 13 chromosome).The growth scan, which is sometimes called the wellbeing scan or positioning scan, takes place when you are between 23 and 40 weeks pregnant. It checks how well your baby is growing and their position in the uterus (womb).
During the scan we:
- measure the baby’s head, abdomen and thigh bone
- assess the amount of amniotic fluid around the baby
- observe the baby’s activity
- measure the blood flow in the umbilical cord using Doppler ultrasound
- record the position of the placenta.
The measurements of the head, tummy and leg allow us to estimate fetal weight. We plot all the measurements on a chart against the normal range and this enables us to assess the fetal growth. Your baby is likely to be an average size if the measurements are all within normal limits. If concerns arise from the results of this scan, you will have the opportunity to discuss their implications with our consultant obstetrician.
The baby’s position usually becomes stable from 34 weeks onwards. Hence we can perform a scan to determine the position at this stage. If the scan reveals a breech position we can then discuss options open to you such as external cephalic version (ECV) or caesarean section. ECV is the act of turning the baby by hand. Your baby is breech when their bottom, foot or feet, instead of their head, leads the way out of the uterus.
Amniocentesis can be done for various reasons:
- Genetic testing. Genetic amniocentesis involves taking a sample of amniotic fluid and testing it for certain conditions, such as Down syndrome.
- Fetal lung testing. Fetal lung maturity testing involves taking a sample of amniotic fluid and testing it to determine whether a baby’s lungs are mature enough for birth.
- Diagnosis of fetal infection. Occasionally, amniocentesis is used to evaluate a baby for infection or other illness. The procedure can also be done to evaluate the severity of anemia in babies who have Rh sensitization — an uncommon condition in which a mother’s immune system produces antibodies against a specific protein on the surface of the baby’s blood cells.
- Treatment. If you accumulate too much amniotic fluid during pregnancy (polyhydramnios), amniocentesis might be done to drain excess amniotic fluid from your uterus.
- Paternity testing. Amniocentesis can collect DNA from the fetus that can then be compared to DNA from the potential father.
Chorionic villus sampling (CVS), sometimes called “chorionic villous sampling” (as “villous” is the adjectival form of the word “villus”), is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus (placental tissue) and testing it for chromosomal abnormalities, usually with FISH or PCR. CVS usually takes place at 10–12 weeks’ gestation, earlier than amniocentesis or percutaneous umbilical cord blood sampling. It is the preferred technique before 15 weeks.
Possible reasons for having a CVS can include:
- Abnormal first trimester screen results
- Increased nuchal translucency or other abnormal ultrasound findings
- Family history of a chromosomal abnormality or other genetic disorder
- Parents are known carriers for a genetic disorder
- Advanced maternal age (maternal age above 35). AMA is associated with increase risk of Down’s syndrome and at age 35, risk is 1:400. Screening tests are usually carried out first before deciding if CVS should be done.
Considering a 3D or 4D sonogram keepsake of your cutie? Here’s what you need to know about the latest ultrasounds during pregnancy – from what they do to whether they’re safe.
Ultrasounds in 3D and 4D are performed only to closely examine suspected fetal anomalies, such as cleft lip and spinal cord issues, or to monitor something specific. In other words, 3D sonograms and 4D ultrasounds are usually not part of routine prenatal exams.
- 3D ultrasounds: For 3D ultrasounds, multiple two-dimensional images are taken at various angles and then pieced together to form a three-dimensional rendering. For instance, instead of just seeing a profile view of your cutie’s face, in a 3D sonogram you can see the whole surface (it looks more like a regular photo).
- 4D ultrasounds: A 4D ultrasound is similar to a 3D ultrasound, but the image shows movement like a video would. So in a 4D sonogram, you’d see your baby doing things in real time (like opening and closing his eyes and sucking his thumb).
A nuchal translucency scan is part of the ultrasound scan that most pregnant women have at around 12 weeks of pregnancy. If you decide to have the scan, the health professional performing the ultrasound will measure your baby’s nuchal translucency (a fluid-filled space at the back of your baby’s neck).
The results of a nuchal translucency scan may tell you if your baby has a high or low risk of a chromosomal abnormality. Examples of chromosomal abnormalities include trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome) or trisomy 13 (Patau syndrome).
The nuchal translucency scan is done between 11 and 14 weeks of pregnancy. It might need to be done alone, or it might be able to be done while you’re having your dating scan.
Usually the scan is done through your abdomen but occasionally the nuchal translucency can only be seen by inserting a probe into the vagina.
You might also be offered a blood test around this time. Your doctor can look at the results of the combined test (blood test and nuchal translucency scan) to get a more accurate picture of the risk of a chromosomal abnormality.
The results of the nuchal translucency scan will not be used alone to calculate the risk of a chromosomal abnormality. All your first trimester screening is combined to calculate your risk. The calculation based on the mother’s age, the nuchal translucency measurement of your baby, the gestational age of the baby, blood tests and the baby’s nasal bone.
If you have a risk of 1 in 300 or greater (e.g. 1 in 150) you are considered to be in the “increased risk” category.
Even if you are classified as high risk, remember your baby probably doesn’t have a chromosomal abnormality. You may be referred to a genetic counsellor. They will discuss your options and help you to decide if you would like to have a more invasive diagnostic test, such as chorionic villus sampling (CVS) or amniocentesis. These diagnostic tests can tell you definitively if your baby has a chromosomal abnormality or not. Tests such as CVS and amniocentesis carry a small risk of miscarriage.
Doppler sonography is a technique that uses reflected sound waves to measure movements such as blood flow and heartbeat. Doppler ultrasound scans can be used to determine the speed and direction of the blood flow. This information can be helpful in determining if the foetal growth is normal and whether the tissues are supplied with enough blood and nutrients. Doppler scans are performed with the same apparatus as a regular ultrasound scan and are normally used during the third trimester on women who have high-risk pregnancies.
A nuchal translucency screening, or NT screening, is a routine ultrasound performed between week 11 and week 13 of pregnancy. Fetuses with increased fluid at the base of their necks may have a chromosomal problem such as Down syndrome. Nuchal Translucency Scan is a Prenatal Screening, which means the results can’t tell you for sure whether your child has a chromosomal disorder, only the statistical likelihood. It’s often combined with a blood test to offer more insight into the relative odds of your baby being born with a genetic disorder.
When a nuchal translucency screening is done?
NT screening must be performed between 11 and 13 weeks of pregnancy. After that, the tissue gets so thick that it’s no longer translucent, making test results inconclusive.
What does nuchal translucency measure?
NT focuses on a small, clear space at the back of a growing baby’s neck called the nuchal fold. Experts have found that this spot tends to accumulate fluid and, as a result, expands in size in babies who have genetic abnormalities like Down syndrome (caused by an extra copy of chromosome 21, one of the 23 pairs of chromosomes that contain a person’s genetic code), trisomy 18 (an extra copy of chromosome 18) and trisomy 13 (an extra number 13 chromosome).
The growth scan, which is sometimes called the wellbeing scan or positioning scan, takes place when you are between 23 and 40 weeks pregnant. It checks how well your baby is growing and their position in the uterus (womb).
During the scan we:
- measure the baby’s head, abdomen and thigh bone
- assess the amount of amniotic fluid around the baby
- observe the baby’s activity
- measure the blood flow in the umbilical cord using Doppler ultrasound
- record the position of the placenta.
The measurements of the head, tummy and leg allow us to estimate fetal weight. We plot all the measurements on a chart against the normal range and this enables us to assess the fetal growth. Your baby is likely to be an average size if the measurements are all within normal limits. If concerns arise from the results of this scan, you will have the opportunity to discuss their implications with our consultant obstetrician.
The baby’s position usually becomes stable from 34 weeks onwards. Hence we can perform a scan to determine the position at this stage. If the scan reveals a breech position we can then discuss options open to you such as external cephalic version (ECV) or caesarean section. ECV is the act of turning the baby by hand. Your baby is breech when their bottom, foot or feet, instead of their head, leads the way out of the uterus.
Amniocentesis is a procedure in which amniotic fluid is removed from the uterus for testing or treatment. Amniotic fluid is the fluid that surrounds and protects a baby during pregnancy. This fluid contains fetal cells and various proteins.
Amniocentesis can be done for various reasons:
- Genetic testing. Genetic amniocentesis involves taking a sample of amniotic fluid and testing it for certain conditions, such as Down syndrome.
- Fetal lung testing. Fetal lung maturity testing involves taking a sample of amniotic fluid and testing it to determine whether a baby’s lungs are mature enough for birth.
- Diagnosis of fetal infection. Occasionally, amniocentesis is used to evaluate a baby for infection or other illness. The procedure can also be done to evaluate the severity of anemia in babies who have Rh sensitization — an uncommon condition in which a mother’s immune system produces antibodies against a specific protein on the surface of the baby’s blood cells.
- Treatment. If you accumulate too much amniotic fluid during pregnancy (polyhydramnios), amniocentesis might be done to drain excess amniotic fluid from your uterus.
- Paternity testing. Amniocentesis can collect DNA from the fetus that can then be compared to DNA from the potential father.
Source : Mayo Clinic
Chorionic villus sampling (CVS), sometimes called “chorionic villous sampling” (as “villous” is the adjectival form of the word “villus”), is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus (placental tissue) and testing it for chromosomal abnormalities, usually with FISH or PCR. CVS usually takes place at 10–12 weeks’ gestation, earlier than amniocentesis or percutaneous umbilical cord blood sampling. It is the preferred technique before 15 weeks.
Possible reasons for having a CVS can include:
- Abnormal first trimester screen results
- Increased nuchal translucency or other abnormal ultrasound findings
- Family history of a chromosomal abnormality or other genetic disorder
- Parents are known carriers for a genetic disorder
- Advanced maternal age (maternal age above 35). AMA is associated with increase risk of Down’s syndrome and at age 35, risk is 1:400. Screening tests are usually carried out first before deciding if CVS should be done.
Considering a 3D or 4D sonogram keepsake of your cutie? Here’s what you need to know about the latest ultrasounds during pregnancy – from what they do to whether they’re safe.
Ultrasounds in 3D and 4D are performed only to closely examine suspected fetal anomalies, such as cleft lip and spinal cord issues, or to monitor something specific. In other words, 3D sonograms and 4D ultrasounds are usually not part of routine prenatal exams.
- 3D ultrasounds: For 3D ultrasounds, multiple two-dimensional images are taken at various angles and then pieced together to form a three-dimensional rendering. For instance, instead of just seeing a profile view of your cutie’s face, in a 3D sonogram you can see the whole surface (it looks more like a regular photo).
- 4D ultrasounds: A 4D ultrasound is similar to a 3D ultrasound, but the image shows movement like a video would. So in a 4D sonogram, you’d see your baby doing things in real time (like opening and closing his eyes and sucking his thumb).
Doppler sonography is a technique that uses reflected sound waves to measure movements such as blood flow and heartbeat. Doppler ultrasound scans can be used to determine the speed and direction of the blood flow. This information can be helpful in determining if the foetal growth is normal and whether the tissues are supplied with enough blood and nutrients. Doppler scans are performed with the same apparatus as a regular ultrasound scan and are normally used during the third trimester on women who have high-risk pregnancies.