Expert prenatal care through advanced tools.

An obstetric or fetal ultrasound, also commonly known as a sonogram, is an imaging technique radiologists use to produce images of a fetus in the uterus, enabling you and your physician to monitor its growth and development as your pregnancy progresses. Through the use of high-frequency sound waves, an ultrasound gathers information from internal reflections that are assembled into a complete picture on the ultrasound monitor. The procedure is performed topically (on the surface of the skin) and uses a liquid gel to provide the highest quality images.

There is no definitive schedule for how many scans a woman should have during pregnancy. However, ultrasounds are commonly performed during the first trimester (at about seven weeks), to confirm pregnancy and establish a timeline, and again during the second trimester (at 18 to 20 weeks) to monitor development and determine the presence of any congenital malformations.

First introduced in the 1950s, the obstetric ultrasound has since become the benchmark for determining gestational age, size and development of a fetus. Popular for their ability to provide that “first look” of your unborn baby, ultrasounds clearly depict your baby's profile and also display his or her heartbeat well before delivery. Other beneficial applications include:

Early confirmation of pregnancy. The gestational sac can be detected via ultrasound as early as four and a half weeks into gestation, with the yolk sac visible around five weeks. After five and a half weeks, an ultrasound enables the radiologist to observe and measured the embryo. It is also highly useful for confirming that the pregnancy is occurring within the cavity of the uterus as well as determining vaginal bleeding during early pregnancy.

Assessment of fetal size to determine gestational age. Ultrasounds enable radiologists to establish the gestation age of the embryo for patients who are uncertain of their last menstrual period, providing a clear and accurate timeline for development and delivery. A visible heartbeat can be detected by ultrasound about six weeks into the pregnancy and is usually clearly visible by seven weeks. If the heartbeat is visible, the probability of continued pregnancy is better than 95 percent. And if you wish to know the gender of your baby, it can usually be determined after 20 weeks.

Diagnosing malformations of the fetus. Many structural abnormalities in the fetus can be accurately diagnosed through an ultrasound, often before 20 weeks into gestation, to determine the viability of the fetus.

Discovering multiple pregnancies. An ultrasound is an invaluable tool that enables a radiologist and your physician to determine the number of fetuses, the chorionicity (identical or non-identical), fetal presentations, evidence of growth and any fetal anomalies that may be present.

Measuring amniotic fluid to determine hydramnios and oligohydramnios. The excessive or insufficient amount of amniotic fluid can have a negative impact on the fetus. Both are clearly-viewable by ultrasound.

Is an ultrasound safe for me and my baby?

Yes. Unlike an x-ray, an obstetric ultrasound does not involve radiation. There is currently no documented risk to women or their developing babies and it is therefore considered to be a safe, non-invasive, accurate and cost-effective method of monitoring your pregnancy.


We’d like you to meet Amber. She came to Longview Radiologists for her obstetric ultrasound scans in 2009. Amber was pleased with our services and felt right at home here. She’d also tell you that few things compare to the experience of seeing your baby for the first time. Watch her story.