Ultrasound is the use of sound waves directed at the developing baby and then made into an image on a video screen.
Ultrasound provides important information about your pregnancy. Such as:
- verifying your due date
- finding out if there is more than one baby (twins or triplets)
- confirming the position of the placenta and the baby
- measuring the amount of amniotic fluid
- monitoring the development of the baby
- detecting some birth defects
- recognizing when there has been a miscarriage
Your doctor, nurse practitioner or nurse midwife usually performs an ultrasound early in your pregnancy to help confirm your due date and count the number of fetuses.
A second-trimester ultrasound, done in the ultrasound department at about 17-20 weeks of pregnancy, is routinely offered to all pregnant women. This ultrasound may also be called a "fetal anatomy survey" or a "level 1 scan". The exam will include a careful head-to-toe evaluation of the fetus to make sure the anatomy looks normal. The sonographer also evaluates the position of the fetus, the location of the placenta, and the amount of amniotic fluid. Often the baby's gender (boy or girl) can be determined during this ultrasound.
Risks: Ultrasound has been routinely used in pregnancy since the 1960s. Based on a large number of medical studies, there are no known health risks to the fetus or mother associated with routine use of prenatal ultrasound.
Results: Most prenatal ultrasound results are normal. Your doctor, nurse practitioner or nurse midwife will discuss your routine ultrasound results with you. Although a normal scan is reassuring, it does not guarantee that the baby will be completely normal. Prenatal ultrasound cannot diagnose all malformations and problems of an unborn baby.
Some women may be offered follow-up tests after their ultrasound.
A more detailed ultrasound, sometimes called a level 2 ultrasound or high resolution ultrasound, may be offered when the initial scan shows questionable findings or abnormalities, when the fetal anatomy is not well-visualized on the routine scan, or in the case of a positive screening test.
Some common ultrasound findings include:
- Choroid plexus cysts [Spanish version]
- Cystic hygroma [Spanish version]
- Echogenic bowel [Spanish version]
- Echogenic intracardiac focus [Spanish version]
- Gastroschisis [Spanish version]
- Large nuchal translucency (NT) [Spanish version]
- Single umbilical artery [Spanish version]
- Dilated renal pelvis [Spanish version]
- Mild ventriculomegaly [Spanish version]
Reviewed by: Kaiser Permanente Genetics