Ultrasound is the most commonly used medical imaging technology in pregnancy to view the unborn fetus and determine the health of the pregnancy. Throughout each trimester, ultrasound imaging, also called sonography, is used to ensure both the mother and fetus are doing well. Current ultrasound technology allows for traditional two-dimensional (2D) imaging as well as the more recent 3D and 4D (or 3D video) evaluations.
Ultrasound is generally considered safe in pregnancy for medical diagnostic purposes with focused evaluations. However, this does not mean any and every ultrasound procedure is recommended, such as so-called “keepsake” ultrasound images and video. The safety of unnecessary prolonged ultrasound exposure for entertainment purposes has not been well studied in in the medical literature and is not currently advocated by national organizations (FDA, AIUM, ACOG, SMFM).
Ultrasound imaging devices work by emitting high-frequency sound waves (far above the threshold for human hearing) that are reflected by the tissues of the human body. The handheld device both emits and detects these sound waves, measuring the time it took each wave to be reflected back to the handpiece.
Because certain tissues, like bone, fluid, and soft tissue, reflect sound differently than others, certain boundaries can be identified in the timing of reflected ultrasound pulses. This is what creates the image you and the physician see in the ultrasound monitor, or sonogram.
There are no known or proven harmful effects of medical diagnostic ultrasound to human fetuses when using standard clinical settings on the machines.
In the first trimester, ultrasound is used to identify the location, viability, and number of fetuses present. Most importantly, it confirms the gestational age of the pregnancy to allow for proper timing of care throughout the remainder of pregnancy. Finally, screening for chromosomal/genetic problems can be provided to patients if desired through various nuchal translucency screening programs.
In the second trimester, ultrasound imaging is used to evaluate the fetal anatomy and possibly to evaluate the cervical length as a marker of risk for pre-term birth often based upon certain risk factors.
In the third trimester, ultrasound is used to assess fetal growth and well-being based upon various clinical indications to be reviewed with individual care providers. If fetal growth is determined to be poor, our physicians may evaluate the blood flow in the umbilical cord in order to determine the health of the placenta.
Ultrasound is also used to guide the specialist when performing invasive testing such as Chorionic Villous Sampling (evaluation of placental tissue) or amniocentesis (evaluation of fluid taken from the sac surrounding the baby).
We advise our patients to prepare for ultrasound testing by wearing loose-fitting two-piece outfits on the day of the appointment. In general, only the abdominal area needs to be exposed during an ultrasound procedure, which is often painless.
Often in the first trimester, transvaginal ultrasound may be required in order to evaluate the early pregnancy, or in the second and third trimesters to more accurately measure the cervical length in appropriately determined patients.
Clear ultrasound gel is used on the abdomen to allow the transducer to make secure contact with the skin, thereby providing a continuous path for the sound waves to enter the body. Images are captured on a screen and will be interpreted by our trained medical professionals. The pictures taken during a routine medical ultrasound appointment can be printed or electronically sent to various multimedia platforms for keepsakes.
Transvaginal imaging requires inserting a narrow endocavitary probe specifically developed for this imaging technique. A protective disposable plastic cover is placed over the transducer, lubricated with a small amount of gel, and then placed in the lower part of the vagina.
This type of ultrasound imaging is performed in the traditional gynecologic position, with patients lying on their backs with both legs placed in foot rests.
Ultrasound images are generally completed within 30 minutes and patients can immediately resume their normal activity. In some centers, the physicians interpreting the results will share their findings, while in other centers the physicians will simply send a report to your primary care provider and they will review the findings with you.
In both low- and high-risk pregnancies, additional testing may be performed during routine appointments for a number of reasons. These include to detect potential genetic birth defects, check on the health of the baby, and to identify potential concerns due to a family or personal history of miscarriage, abnormal bleeding, or infertility.
Our patients or physicians may seek chorionic villus sampling to detect certain birth defects and genetic abnormalities that could put the baby’s health at risk. In this procedure, a small piece of the placenta is taken out and genetically tested. CVS is performed relatively early in pregnancy, between 10 and 13 weeks, typically, and is not needed for all pregnancies.
Ultrasound imaging is used during CVS to guide the physician to the placenta and carefully obtain a sample of tissue without disturbing vital tissues.
Also known as “amnio,” amniocentesis is a test to diagnose certain health conditions in a growing baby. It is not performed in every pregnancy, and is often done later in pregnancy than other tests, like CVS. Amnio involves removing a small amount of amniotic fluid—the substance that surrounds and cushions the fetus in the womb—and analyzing it for compounds that would indicate certain illnesses or genetic defects.
Similar to how it’s used during CVS, ultrasound during amniocentesis allows specialists to locate the fetus and placenta to ensure no vital structures are disturbed when removing the amniotic fluid.
Regular ultrasound images are safe and necessary during pregnancy to check on the health and growth of a fetus. When used in a proper medical environment with a trained technician, they pose no risk to your health and can provide images that help mother and baby bond even before birth.
At Carnegie Women’s Health, we’re proud to be your partner in health and wellness before, during, and after pregnancy. To learn more about our comprehensive services, call us or contact us online today.
- FDA Consumer Update on Ultrasound
Maternal Fetal Medicine blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!