An ultrasound during pregnancy uses sound waves to create images of the developing baby and surrounding structures. This non-invasive imaging technique provides valuable information to healthcare providers throughout the prenatal period, serving as a routine part of monitoring health.
The Usual Timing
The first pregnancy ultrasound typically occurs early in the first trimester, often between 6 and 10 weeks. This timing is calculated from the first day of the last menstrual period (LMP), the standard method for determining gestational age. While some providers may perform a scan as early as 5 weeks, the 6-10 week window is common for confirming early pregnancy details.
Why It’s Done Early
An early ultrasound serves several purposes in prenatal care. It confirms the pregnancy and verifies its location within the uterus, helping rule out an ectopic pregnancy. Early scans are also highly accurate for determining gestational age, providing a reliable estimated due date by measuring the embryo’s crown-rump length. This measurement is precise in the first trimester because fetal growth is consistent at this stage.
Detecting the fetal heartbeat is another aspect of this early scan, indicating pregnancy viability. A heartbeat can often be seen as early as 6 to 7 weeks. An early ultrasound can also identify multiple pregnancies, such as twins or triplets, which is important for planning specialized prenatal care due to increased risks. The scan also allows providers to assess uterine health and rule out certain abnormalities.
What Happens During Your Appointment
During your first ultrasound, a sonographer or doctor uses a transducer to send sound waves into your body, creating images on a screen. In early pregnancy, a transvaginal ultrasound is often preferred. This method involves inserting a small, lubricated probe into the vagina, providing clearer images of the embryo and pelvic organs.
For a transabdominal ultrasound, used if the pregnancy is further along or with a transvaginal scan, a water-soluble gel is applied to your lower abdomen. The transducer is moved across the skin to capture images. You may need a full bladder, which helps push the uterus higher for better viewing. The sonographer will look for the gestational sac, developing embryo, and fetal heartbeat.
When Timing Might Differ
While a first ultrasound commonly occurs between 6 and 10 weeks, timing can vary. An earlier scan, possibly between 5 and 6 weeks, may occur due to concerns like vaginal bleeding, severe nausea, a history of ectopic pregnancy, or if pregnancy resulted from fertility treatments like IVF.
Conversely, some individuals might have their first ultrasound later in the first or second trimester. This can happen if menstrual periods are irregular, making it difficult to estimate the conception date, or if prenatal care begins later. In such cases, the dating scan might occur closer to 12 weeks, adapting to the pregnant person’s specific health needs and history.