An ultrasound, also known as a sonogram, is a diagnostic imaging technique that uses high-frequency sound waves to create real-time images. During pregnancy, sound waves are directed into the body, bouncing off the baby, placenta, and uterus. A computer translates these echoes into visual images. This non-invasive procedure allows healthcare providers to monitor the developing baby without using radiation.
Understanding Ultrasound Safety
Medical ultrasounds are considered safe for both the pregnant individual and the developing baby because they do not use ionizing radiation, unlike X-rays. Instead, they rely on sound waves, which are a form of mechanical energy. Major medical organizations, such as the American College of Obstetricians and Gynecologists (ACOG), confirm that diagnostic ultrasounds, when performed by trained professionals for medical reasons, have no reported adverse fetal effects.
The principle of “As Low As Reasonably Achievable” (ALARA) guides the use of ultrasound in medicine, suggesting exposure be minimized while obtaining necessary diagnostic information. Ultrasound energy can produce bioeffects like thermal effects (heating of tissues) and cavitation (formation of microscopic bubbles), but these are not a concern in diagnostic settings. Modern ultrasound machines control power levels and exposure times to keep these effects well below harmful thresholds, with indicators displayed to help operators monitor and minimize potential risks.
Standard Number of Ultrasounds
For most uncomplicated pregnancies, a standard schedule includes one or two ultrasound scans. The first scan occurs in the first trimester, usually between 6 and 9 weeks, to confirm the pregnancy, estimate the due date by measuring the crown-rump length, and check for the baby’s heartbeat. This early scan also helps determine if there are multiple pregnancies and ensures the pregnancy is located correctly within the uterus.
The second routine ultrasound, referred to as the anatomy scan or level 2 ultrasound, is performed between 18 and 22 weeks of pregnancy. This comprehensive examination evaluates the baby’s anatomy for proper development, checks the position of the placenta, and assesses the amniotic fluid levels. These two scans are sufficient for routine monitoring in a healthy pregnancy with no complications.
When Additional Ultrasounds Are Needed
More than the standard number of ultrasounds may be required during pregnancy, and these additional scans are still considered safe and beneficial for managing the pregnancy. For instance, an early scan may be repeated if there is uncertainty about the due date or if there are symptoms like vaginal bleeding or abdominal pain. High-risk pregnancies, such as those involving maternal health conditions like diabetes or high blood pressure, necessitate additional monitoring with more frequent ultrasounds.
Further scans may also be performed to monitor fetal growth if there are concerns about the baby being too large or too small, or to check the baby’s position closer to term. Multiple pregnancies involve more frequent ultrasounds to monitor the growth and well-being of each baby. If issues like placenta previa (where the placenta covers the cervix) are suspected, additional ultrasounds are performed to track its location and ensure a safe delivery.