Fetal Ultrasound

Obstetric Ultrasound, Pregnancy Ultrasound, Sonogram, Fetal, Ultrasound, Fetal, Ultrasound, Obstetric, Ultrasound, Pregnancy

Why It Is Done

Fetal ultrasound is done to learn about the health of the fetus. Different information is gained at different times (trimesters) during your pregnancy.

• 1st-trimester fetal ultrasound is done to:
  • Determine how your pregnancy is progressing.
  • Find out if you are pregnant with more than 1 fetus.
  • Estimate the age of the fetus (gestational age).
  • Estimate the risk of a chromosome defect, such as Down syndrome.
  • Check for birth defects that affect the brain or spinal cord.
• 2nd-trimester fetal ultrasound is done to:
  • Estimate the age of the fetus (gestational age).
  • Look at the size and position of the fetus, placenta, and amniotic fluid.
  • Determine the position of the fetus, umbilical cord, and the placenta during a procedure, such as an amniocentesis or umbilical cord blood sampling.
  • Detect major birth defects, such as a neural tube defect or heart problems.
• 3rd-trimester fetal ultrasound is done to:
  • Make sure that a fetus is alive and moving.
  • Look at the size and position of the fetus, placenta, and amniotic fluid.

Transvaginal ultrasound is generally done early in a pregnancy to determine fetal age or to detect a suspected ectopic pregnancy. It is occasionally done late in pregnancy to determine the location of the placenta or in a high-risk pregnancy to monitor the length of the cervix.

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Author:	Maria G. Essig, MS, ELS	Last Updated: June 28, 2007
Medical Review:	Adam Husney, MD - Family Medicine Joy Melnikow, MD, MPH - Family Medicine Deborah A. Penava, BA, MD, FRCSC, MPH - Obstetrics and Gynecology
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