Ultrasound scans offer a non-invasive, accurate diagnostic tool for dating a pregnancy, checking for any problems, and obtaining information about the fetus. An ultrasound exam uses high-frequency sound waves to scan a woman’s abdomen and pelvic cavity, creating a picture (sonogram) of the baby and placenta. It does not use X-rays or other types of radiation that could harm a fetus, and may be used as early as the fifth week of pregnancy.
At UC San Diego Health, our machinery allows us to analyze complete, three-dimensional (3D) pictures of a fetus. We also have the capability to perform 4D ultrasound, which allows moving 3D images.
Except for the first-trimester ultrasound to confirm a pregnancy, ultrasounds are typically performed at our Maternal-Fetal Care and Genetics Center in Sorrento Valley, one of only a few San Diego County centers accredited by the American Institute of Ultrasound in Medicine in both obstetric ultrasound and fetal echocardiography. A radiologist or perinatologist reviews all results.
The following schedule describes the ultrasounds that women experiencing a typical pregnancy may receive. Your care provider may recommend a different schedule.
First trimester: You may receive an ultrasound scan in your provider's office to:
- Confirm a viable pregnancy
- Assess the baby's age
- Assess the baby's heart rate
- Identify multiple pregnancies
11-14 weeks: You may opt to receive a nuchal translucency (NT) ultrasound scan, which measures the clear space in the tissue at the back of the neck. In conjunction with blood tests offered by the California Prenatal Screening Program, this scan can identify fetal or chromosomal issues including Trisomy 18 and Down syndrome.
16-20 weeks: If amniocentesis is performed, ultrasound technology will be used to guide the needle and collect the amniotic fluid for testing.
18-22 weeks: An ultrasound scan is routinely performed to:
- Assess the size and anatomy of the fetus
- Identify birth defects
- Determine the position of the fetus, umbilical cord, and placenta
- Identify any cervical issues that may lead to preterm labor
It's often possible to determine gender at the 18-22 week scan as well.
Third trimester: Ultrasounds scans will be performed as needed to monitor growth disorders, multiple pregnancies, and women with diabetes, hypertension or other medical conditions.