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Obstetric Ultrasound

Obstetric ultrasounds provide pictures of an embryo or fetus within a woman's uterus, as well as the mother's uterus and ovaries.

During an obstetric ultrasound, the examiner may evaluate blood flow in the umbilical cord or, in some cases, assess blood flow in the fetus or placenta using a Doppler ultrasound. A Doppler ultrasound is a technique that evaluates blood flow through a blood vessel, including the body's major arteries and veins in the abdomen, arms, legs and neck.

What Are Some Common Uses of the Procedure?

An obstetric ultrasound is a useful clinical test to:

  • Establish the presence of a living embryo/fetus
  • Estimate age of a pregnancy
  • Diagnose congenital abnormalities of the fetus
  • Evaluate the position of the fetus
  • Evaluate the position of the placenta
  • Determine if there are multiple pregnancies
  • Determine the amount of amniotic fluid around the baby
  • Check for opening or shortening of the cervix
  • Assess fetal growth
  • Assess fetal well-being

How Should I Prepare?

You should wear a loose-fitting, two-piece outfit for the examination. Only the lower abdominal area needs to be exposed during this procedure. If an ultrasound is ordered by your clinician early in your pregnancy, you may be instructed to have a full bladder for the procedure. Air interferes with sound waves, so if your bladder is empty, the air-filled bowel is pushed out of the way by the bladder and an image of the uterus and embryo or fetus can be obtained.

Download our obstetric ultrasound prep manual to learn more about preparing for this procedure.

How Is the Procedure Performed?

For most ultrasound exams, the patient is positioned lying face-up on an examination table that can be tilted or moved. A clear, water-based gel is applied to the area of the body being studied to help the transducer make secure contact with the body and eliminate air pockets between the transducer and the skin. The sonographer or radiologist then presses the transducer firmly against the skin in various locations, moving over the area of interest or angling the sound beam from a farther location to better see an area of concern.

Sometimes the radiologist determines that a transvaginal scan needs to be performed. This technique often provides improved, more detailed images of the uterus and ovaries. This method of scanning is especially useful in early pregnancy.

A transvaginal ultrasound is performed very much like a gynecologic exam and involves the insertion of the transducer into the vagina after you empty your bladder. The tip of the transducer is smaller than the standard speculum used when performing a Pap smear. A condom is placed over the transducer, lubricated with a small amount of gel and then inserted into the vagina.

Only two to three inches of the transducer end are inserted into the vagina. The images are obtained from different orientations to get the best views of the uterus and ovaries. Transvaginal ultrasounds are usually done while lying on your back, possibly with your feet in stirrups, similar to a gynecologic exam.

When the examination is complete, you may be asked to dress and wait while the ultrasound images are reviewed.

What Will I Experience During and After the Procedure?

Most ultrasound examinations are painless, fast and easy. There is usually no discomfort from pressure as the transducer is pressed against the area being examined.

If scanning is performed over an area of tenderness, you may feel pressure or minor pain from the transducer. At times, the sonographer may have to press more firmly to get closer to the embryo or fetus to visualize the structure better. Any discomfort is usually minimal and temporary.

If a Doppler ultrasound study is performed, you may actually hear pulse-like sounds that change in pitch as the blood flow is monitored and measured.

With transvaginal scanning, there may be minimal discomfort as the transducer is moved into the vagina. In most cases, there are no after-effects and you can return to your normal activities immediately. Rarely, though, you may be slightly sore or might have a light pink discharge for a day or two.

What Are the Benefits and Risks of Ultrasounds?


  • Noninvasive (no needles or injections) and usually painless.
  • Widely available, easy to use and less expensive than other imaging methods.
  • Do not use any ionizing radiation.
  • Preferred imaging modality for the diagnosis and monitoring of pregnant women and their unborn babies.
  • Have been used to evaluate pregnancy for nearly four decades with no evidence of harm to the patient, embryo or fetus.
  • Allow doctors to see inside the uterus and provide information about the pregnancy.


  • For standard diagnostic ultrasounds, there are no known harmful effects.

Who Interprets the Results and How Do I Get Them?

Our board-certified radiologists will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.

If you would like to schedule an appointment, please call 678-312-3444.