Some reasons your doctor may have ordered an ultrasound:

  • To check on your dates (the estimated age of the fetus).
  • Unexpected vaginal bleeding during the pregnancy.
  • To determine the position of the baby in the womb (head down vs. feet down).
  • To determine the cause for an unexpectedly large pregnancy, such as twins.
  • To inspect the fetus thoroughly for abnormalities if the mother has been placed into a "high risk" group.

How do you prepare for an obstetrical ultrasound?

  • Depending on the stage of pregnancy, you may be asked to fill your bladder by drinking water prior to the exam.

What happens during my ultrasound examination?

  • You will probably change into a patient gown.
  • You will meet the sonographer, the person who will perform most of the scan. This trained technologist is an expert in ultrasound scanning. Most have been certified by the American Registry of Diagnostic Medical Sonographers (ARDMS).
  • You will lie comfortably on an examination table. The sonographer will place warmed ultrasound gel on your abdomen. This gel helps the sound to penetrate through your skin.
  • The sonographer will thoroughly scan the fetus and uterus. This scan may be videotaped, and/or films or prints made of the scan.
  • The sonographer may leave the room to show the pictures to a radiologist. This radiologist is responsible for interpreting these images and issuing a written report to your doctor.
  • Quite frequently, the radiologist will come into the room and do some additional scanning to clarify any questions that might not have been answered by the sonographer's initial scanning.
  • Early in pregnancy, endovaginal (transvaginal) scanning may be performed. After elevating the hips with a pillow or pad, the sonographer places a sterilely covered, cleansed endovaginal probe into the vagina. This special probe gets much closer to the uterus and is helpful in visualizing early pregnancies and small fetal parts. As the fetus grows, endovaginal scanning is less helpful and transabdominal scanning, described above, replaces it.