Ultrasound involves the use of sound waves to pass inside a mother's body to create a picture of the fetus and uterus. Ultrasound does not involve any radiation exposure and is safe in pregnancy. Ultrasound can be used to determine the age, size, and anatomy of the fetus as well as look at the mother's uterus and cervix.
A two-dimensional ultrasound, one of the most common prenatal tests, is a moving image made with sound waves. Most pregnant women have at least one ultrasound test, and women with complicated pregnancies may require more.
Three-dimensional and four-dimensional ultrasounds
Three-dimensional and four-dimensional ultrasounds (h2)
Three-dimensional (3D) and four-dimensional (4D) ultrasounds are both sophisticated technologies that produce a more life-like image of the infant. The difference between the two is that 3D images are still photographs, while 4D images show the baby moving.
Perinatologists in Bridgeport Hospital's Antenatal Testing Unit use these advanced images as an addition to standard ultrasound (2D) when the baby is being evaluated in the womb.
For example, 3D/4D ultrasounds give a better image of the baby’s features when a perinatologist is concerned about abnormalities of the lip, hands or feet. These more detailed images may also help you understand what the physician is seeing.
How is an Ultrasound Performed?
During this painless procedure, a transducer, something like a computer mouse in size, is lightly passed over your abdomen, putting out very high frequency sound waves. The waves are reflected back to the transducer and are turned into a picture on a monitor.
What Information can an Ultrasound Provide?
An ultrasound can provide early confirmation of pregnancy. It can diagnose ectopic or tubal pregnancy (where the pregnancy is implanted within the fallopian tube rather than the uterus) or determine if a miscarriage is occurring. As your baby grows, ultrasound can be used to measure the size of his or her head, femur (long leg bone), and abdominal circumference. An ultrasound can provide clues about the health of the baby by looking closely at the developing organs. It can also diagnose multiple pregnancies, and it can often show whether your baby is a boy or a girl, if you wish to know in advance.
Ultrasounds may be performed at about:
- 6-7 weeks or later to confirm pregnancy and estimate birth date
- 18-20 weeks to scan for birth defects and measure the baby for growth and development
- 34 weeks to evaluate the baby's size and growth again.
- Other scans may be done as needed if further assessment or diagnosis is required.
Level II or Targeted Ultrasound
Level II or Targeted Ultrasound involves the use of sophisticated ultrasound equipment along with specially trained physicians to obtain a detailed look at fetal anatomy. Targeted Ultrasound is recommended when there is an increased risk of birth defects in the fetus either due to previous pregnancy history, family history, medical complications, or advanced maternal age.
Vaginal Sonography is a form of ultrasound in which a vaginal probe is inserted into a woman's vagina and is similar to an internal pelvic examination. This is safe to perform in pregnancy and can provide detailed information concerning early (less than 12 weeks) pregnancies. It is also used to measure a woman's cervix to look for signs of preterm labor.
Biophysical Profile involves using ultrasound to look at the health of the fetus. It is known that fetuses that are getting enough oxygen and nutrition through the placenta will be active and have a normal amount of amniotic fluid surrounding them. A biophysical profile looks at the activity of the fetus, body movements, breathing movements, fetal tone, and amniotic fluid volume.
Doppler Ultrasound uses sound waves to look at blood flow through the fetal or maternal blood vessels. This is useful in cases where the fetus may not be growing normally or may be anemic.
Color-Flow Doppler Ultrasound
Color-Flow Doppler Ultrasound uses specialized ultrasound technology to look at blood flow through fetal organs and can be helpful to better see certain organs and look at blood flow.
Nuchal Translucency Scan (First trimester)
This ultrasound measures the amount of fluid at the back of your baby's neck. The test can determine
- whether you are definitely pregnant
- how many babies you are expecting
- how many weeks pregnant you are
- whether there are any obvious major abnormalities present at this time
- the risk of chromosomal abnormalities, especially Down’s syndrome
The test itself does not carry any risk to the mother or the baby.
In the five decades since the first ultrasounds were performed on pregnant women, there have been no confirmed reports of harm to either the mother or the baby from ultrasound waves.