Fetal ultrasound provides you and your OB-GYN with a first glimpse of your developing baby. An ultrasound produces a picture of the baby to monitor the size and position of the fetus and check for problems. This type of imaging is non-invasive and uses sound waves to produce an image. Ultrasound results may estimate the due date, check for multiple pregnancies, and find major birth defects. No radiation is used, so there is no risk for you or the baby.
- A safe, painless and non-invasive test
- Typically performed between 18 and 20 weeks of pregnancy
- Used to confirm a pregnancy and its location
- Used to determine how a pregnancy is progressing, the baby's growth rate, age and sex.
- Used to determine location and development of the placenta
- Identifies possible fetal abnormalities
Types of Ultrasounds
- Standard - directs high-pitched sounds waves toward the baby, which bounces off tissues, organs and bones in the mother's body, including those of the baby in uterus. This creates black and white images on a monitor.
- Advanced or Targeted - used to further investigate a suspected abnormality identified by a standard ultrasound.
- Three-dimensional (3-D) - offers 3-D images with a high level of detail.
- Four-dimensional (4-D) - offers 3-D images in real time.
- Doppler - measures slight changes in the frequency of the ultrasound waves as they bounce off moving objects, such as blood cells.
How To Prepare
You should wear comfortable, loose-fitting clothing to your prenatal appointment. The test most likely needs to be done with a full bladder. For transvaginal ultrasound or those in late pregnancy, a full bladder usually isn't necessary.
What To Expect
The ultrasound usually takes less than 30 minutes. The patient is usually positioned on an examination table and clear gel is applied to the abdomen. This improves conduction of sound waves and eliminates air between the transducer, a small plastic device that sends out sound waves and records them as they bounce back, and your skin. The transducer moves back and forth over the abdomen, directing sound waves into the uterus and capturing the reflected sounds waves that are digitally converted into images.