Is Ultrasound Safe in Early Pregnancy?

Ultrasound certainly play a major role in the management of normal pregnancy and is invaluable when complications such as bleeding or cramping occur. Because it is a high-frequency sound wave, out of range of the human ear, and not a form of ionizing radiation such as is used in X-ray, it is very safe. On the ends of the transducers—the probes of the ultrasound machine placed either over the abdomen (abdominal probe) or in the vagina (transvaginal probe)—are metal plates or crystals that vibrate in response to an electrical current. Sound waves are sent out, which are then reflected by your tissues according to their differing thickness, or density. A computer in the machine creates an image on the screen, enabling the doctor and the mother to “see” into the uterus and look at the fatus.

Not long ago, ultrasound used to be of great value only in pregnancies that had progressed beyond 6 to 8 weeks. Oil was placed on the mother’s abdomen, after making sure that she had a very full bladder. Then, by moving the probe of the machine over that area, the sound waves passed into the pelvic organs. This required a sometimes uncomfortably full bladder, and the fetal heartbeat could only be detected beyond the 7th to 8th week of pregnancy. Now, however, methods have improved with the introduction of a special transvaginal probe. It is placed into the vagina and lies up against the uterus, tubes, and ovaries. The state of the pregnancy can be examined and the fetal heart can be seen very early in the pregnancy—from at least 4 weeks. This, of course, is a recent major breakthrough. Like the abdominal probe, the vagina probe is safe to use in pregnancy. The clean probe is covered by a sheath like a doctor’s examining glove and lubricated before insertion. It cause little or no discomfort at all.

Ultrasound also helps make intrauterine procedures, carried out in pregnancy, much safer: for example, the placement of the needle when we do an amniocentesis or during extraction of blood from the umbilical cord for special tests.

Both abdominal and transvaginal equipment take only minutes to use and give a wealth of information in early pregnancy. No harm has ever been done either to the fetus or to the mother from ultrasound.