An ultrasound is a non-invasive method to closely monitor the baby in the womb. It helps doctors track the baby’s growth and development to ensure it is all as per expectations. Over the years, gynaecologists have increasingly relied on these USGs for crucial information that helps them make important decisions regarding the delivery, too.
An ultrasound sonogram is an imaging technique that uses sound waves to create an image of the structure inside. Doctors use a prenatal ultrasound to check on the health and development of the fetus.
A pregnancy ultrasound is usually done abdominally, by moving the transducer over the abdomen. In some cases, if the doctor wants a closer look at the fetus, they may ask for a transvaginal ultrasound that is done via the vaginal opening. A transducer is a device that sends out sound waves that bounce off the structure inside to help create an image. These sound waves are harmless unlike the radiation used in X-rays.
Also known as fetal ultrasound, these imaging tests are done only at specific times during the pregnancy and are not repeated unnecessarily. The frequency of these ultrasounds depends on multiple factors and can differ from pregnancy to pregnancy.
A pregnancy ultrasound is the only way a doctor can see and hear the developing fetus. It can help healthcare professionals in the following ways:
1. Find if the pregnancy is molar, eutopic, or ectopic (when the embryo implants outside the uterus).
2. Estimate the due date.
3. Find the location of the placenta (low-lying placenta or placenta previa can cause complications in the pregnancy).
4. Examine the pelvic organs – uterus, cervix and ovaries.
5. See and hear the fetal heartbeat.
6. Determine the gestational age of the fetus.
7. Know if the baby is developing per normal expectations and is the right size for the age.
8. See the baby move.
9. See for fetal movements
10. Identify potential problems with the pregnancy, if any.
11. Detect complications related to pregnancy.
12. Determine the weight of the baby to check if the baby’s weight gain is satisfactory.
13. Check if the baby’s body parts and organs are developing as per the estimation.
14. Screen for congenital conditions and other possible health complications.
Different doctors can ask for different types of ultrasounds at different times for various reasons. In general, you may require two or three ultrasounds throughout your pregnancy. In case of some complications or doubts, more ultrasounds may be required.
In general, doctors will ask for the following ultrasounds throughout the pregnancy:
Early Pregnancy Scan – This ultrasound is taken between weeks 8 and 10 of pregnancy. In many cases, it will be a transvaginal scan as the baby will be too small to detect via an abdominal scan. Some doctors opt for an abdominal scan, too. This scan helps confirm pregnancy, check if the implantation is inside the uterus, and also helps determine the EDD (expected delivery date).
Anomaly Scan – This is the second scan that happens around the 20th week of pregnancy. This scan is done to check for congenital abnormalities like autism and cerebral palsy and also to detect possibilities of Down syndrome in the baby. The scan also checks the fetal development, amniotic sac and fluid levels, placenta and blood flow between the mother and the baby. This USG also evaluates the maternal pelvic organs.
Third Trimester Scan – This scan is usually performed in the second half of the third trimester to ensure the baby is developing along fine and everything is on track. It also checks the position and health of the placenta, the position and movement of the fetus, and also detects abnormalities that have developed since the previous scan. This scan is important to determine if the baby will move into position for the delivery and if the placenta is not blocking the birth canal.
Different types of ultrasounds are available today to help doctors get varied information about the developing fetus. The different types of USG in pregnancy are:
1. 2D Ultrasound – This is the standard two-dimensional imaging of the baby created using sound waves.
2. 3D Ultrasound – A lifelike image of the baby is created for a better view of the baby’s structure. This helps identify congenital defects like heart or skeletal issues.
3. 4D Ultrasound – A live video of the baby moving in the womb. This helps in checking the baby’s body movements, breathing, swallowing and facial features including blinking of the eyes.
4. Transvaginal Ultrasound – An ultrasound done through the vaginal opening. This is usually done in early pregnancy when the baby is still too small to be detected through the abdominal scan. This can also help get a closer look at the mother’s reproductive system and identify an ectopic pregnancy.
5. Doppler Ultrasound – Shows the blood flow between the mother and baby – in the umbilical cord, between the baby and the placenta, and in the baby’s heart.
6. Abdominal Ultrasound – The most common type of ultrasound in pregnancy for a routine check on the baby.
7. Nuchal Translucency Ultrasound – An ultrasound that measures the thickness of the fluid behind the fetus’s neck. It also helps assess the risk of certain birth defects and is usually done between weeks 11 and 14 in pregnancy.
8. Early Anomaly Scan – In case of high-risk pregnancies, this scan is done between weeks 14 and 18 to check for abnormalities.
9. Anomaly Scan – Usually done around the 20th week to check for any abnormalities. This is a routine scan in pregnancy.
10. Mid-Pregnancy Scan – A routine scan is done between weeks 18 and 20 to check the baby’s development.
11. Third Trimester Scan –This scan is done in the third trimester to check the baby’s position, heartbeat and placenta. This is an important scan if you have a low-lying placenta.
12. Fetal Echocardiography – This scan checks the baby’s heart. It is done if the doctor suspects an issue with the baby’s heart or if you have a family history of congenital heart issues.
USG uses sound waves and not radiation. So, it does not have any harmful side effects, thus making it perfectly safe for pregnancy. However, it is not recommended to do ultrasounds very frequently unless there is a need for the same. The regular two or three USGs during a regular pregnancy is enough.
An ultrasound tries to detect possible problems with the pregnancy and the baby. It may miss out on some problems due to the baby’s positioning. If the sound waves do not pick on certain defects, they can be easily missed in an ultrasound.
Also, the USG can only detect possible issues but not confirm them. If an ultrasound pregnancy test detects a possible issue with the mother’s organs, the placenta, or the baby, doctors will follow it up with additional scans and tests to confirm the suspicions.
Ultrasound sonography is very important in pregnancy. They are absolutely safe and cause no harm to the mother or the baby. These imaging tests give crucial information about the pregnancy's progress. Skipping routine ultrasound scans or taking more scans than necessary is not advisable.
