Fetal Medicine

Fetal medicine is a medical speciality that focuses on the health and well-being of the fetus and their expectant mothers. A broad spectrum of maternal-fetal abnormalities can be diagnosed before birth. Early detection and management of these conditions is vital to optimize outcomes for the mother and the baby. Even though significant pregnancies culminate with the delivery of a healthy baby and mother, some of them are inherently high-risk due to a pre-existing risk factor or the development of a new complication through the use of technologies such as advanced ultrasound, biochemical tests, genetic studies and in-utero treatment, fetal medicine specialist can diagnose, prevent and treat various conditions of the fetus and the mother. The fetal medicine specialist works in close collaboration with the Obstetrician to provide the best care for the mother and the fetus in high-risk pregnancy. They also coordinate with clinical geneticists, neonatologists, pediatric surgeons, and other specialists to plan the postnatal adaption of the baby and assist with specific treatment modalities.

The various procedures done by a fetal medicine specialist are outlined below.

• Ultrasound examination

Vital to monitoring fetal health is an in-depth ultrasound examination. The latest ultrasound machines can assess fetal organs using cutting-edge 2D and 3D ultrasound technology. Generally, 4-5 ultrasound examination studies are required during a pregnancy. A high-risk pregnancy may need more ultrasound examinations.

Three scans that are indispensable during pregnancy are the NT scan, detailed anomaly scan, and growth scan.

1. NT scan

This scan is performed between 11 and 13 weeks, 6 days of gestation. In this scan, the fetal medicine specialist measures fluid thickness beneath the fetal neck. If the value of NT is increased, there is an increased risk for chromosomal-genetic abnormalities, congenital anomalies and abnormal neurodevelopment. Further, the NT scan is an excellent opportunity to screen for fetal organs and significant anomalies. Various severe anomalies can be detected during the NT scan.

2. Detailed anomaly scan

This scan is performed between 18 and 23 weeks of gestation. A systematic examination of fetal organs is done to rule out congenital anomalies. If the study is normal, no further assessment is required. If a congenital anomaly is detected, further studies, such as genetic testing, MRI, etc are warranted. Some anomalies are treatable, and consultation is arranged with other specialists, such as pediatric surgeons and pediatric cardiologists, so that that delivery can be planned well ahead of time.

3. Growth scans

These scans are done between 30 to 37 weeks of gestation. The purpose of this scan is to assess the growth of the baby. The condition is termed fetal growth restriction when the baby has not attained its expected weight. This may require frequent monitoring and, in some instances, early delivery. The fetal medicine specialists may perform Doppler studies, which assess the blood flow towards the placenta and inside the umbilical cord. During the growth scan, fetal organs are again evaluated to rule out significant anomalies that are detectable during this period.

4. Specialized ultrasound studies

such as fetal echocardiography and fetal neurosonogram are indicated in certain situations to provide diagnostic clues and guide further management. Serial surveillance of monochorionic pregnancies is essential as they are associated with specific complications that can jeopardize the survival of the twin fetuses.

• Screening tests

The biochemical tests performed during pregnancy include maternal serum markers originating from the placenta and the fetus. Serum levels of these markers, when combined with ultrasound parameters, maternal medical history and biophysical measurements, can predict the fetal risk of Down syndrome and maternal risk for preeclampsia.

Cell-free fetal DNA or NIPT (non-invasive prenatal test) analyses the fetal DNA in maternal blood and provides effective screening for Down syndrome with an accuracy of 99%. Down syndrome is the most common cause of intellectual disability in children. About half of fetuses with Down syndrome do not have any structural malformations during ultrasound study and hence can be potentially undetected. This is where screening tests play an essential role.

Preeclampsia is a condition associated with increased blood pressure in pregnant mothers, usually associated with loss of protein in urine and can lead to life-threatening organ damage and seizures in some women. Accurate prediction of preeclampsia risk can help in preventing the condition in expectant mothers using medications.

• Prenatal diagnostic tests

These include amniocentesis, chorion villus sampling and fetal blood sampling. These tests are done by passing a needle through the mother's belly and collecting fetal samples such as amniotic fluid, chorionic tissue or fetal blood, which is then sent to a specialized laboratory. The indications for doing these tests include-

• Suspicious markers in fetal ultrasound
• Fetal anomalies
• Screen positive biochemical tests
• Previous pregnancy affected with a chromosomal abnormality
• Family history of genetic disease with risk of inheritance in the current pregnancy
• These tests are generally safe when done only for indicated reasons by a fetal medicine specialist.

• Prenatal therapy

Some fetal conditions are potentially treatable during pregnancy. These include fetal anaemia due to Rh D alloimmunization, complicated monochorionic pregnancies, fetal thoracic cysts, diaphragmatic hernia and open spina bifida.