Ultrasound and Obstetrics

One of the modern miracles of obstetrical care has been the introduction of ultrasound imaging. This has made it possible to actually see the baby and its many organ systems. Because of ultrasound, we can accurately determine the due date, whether a baby is alive, how many babies there are, whether the baby’s anatomy is normal and whether or not the baby is growing normally. The first ultrasounds were done in the mid 1960s and with the introduction of real time imaging and vaginal probes in the 1970s and 1980s, it use became the standard of care throughout the world.

Ultrasound records the echoes of high frequency sound to construct an image of the baby. This is no different than a fish finder or radar but the energy levels are set much lower so that cellular damage does not occur. However, this should not be used frivolously. It is not a toy. We do not know what the long term biological effects are and will not for another 30-40 years since we have not been able to follow humans who have had extensive exposure to obstetrical ultrasounds for more than about 25 years. It took almost 50 years from the time that Marie Curie discovered X-Ray until we realized that radiation was potentially dangerous with high level exposure.

Is obstetrical ultrasound necessary at all?

No, if a couple had absolutely certain dates and ultrasound would not alter anything they would do with their pregnancy, it is not necessary unless they have a high risk pregnancy. The pregnancy can be managed clinically. Obviously, very few couples would take this position since virtually everyone wants and is entitled to have more information about their pregnancy.

When is obstetrical ultrasound appropriate?

  • 1st TRIMESTER — to establish dates, that the baby is alive and within the uterus and to determine how many babies are present. It also can determine if multiple births are identical or not. To look for signs of Down Syndrome and other chromosomal defects (NT testing).
  • 2nd TRIMESTER — for a comprehensive anatomical review including looking for structural birth defects and determining gender.
  • 3rd TRIMESTER — to following high risk patients for growth disturbances and fetal well being.

When is obstetrical ultrasound inappropriate?

  1. Ultrasounds should only be done for a reason which would change a medical decision. It is not a toy.
  2. 3D ultrasounds in shopping malls to “see a baby” are wrong.
  3. Likewise, additional ultrasounds beyond the 20 week anatomical study in low risk patients where the baby has normal clinical growth are inappropriate. Any competent obstetrician or midwife should be able to assess normal growth clinically.