A pregnancy ultrasound is a medical imaging procedure that uses sound waves to create images of a developing baby within the womb and the mother’s reproductive organs. This non-invasive technique provides information about the health and development of the pregnancy. It allows healthcare providers to visualize the fetus without using radiation, making it a key part of prenatal care.
Typical Ultrasound Schedule
For uncomplicated pregnancies, a typical schedule often includes one or two ultrasounds. The first routine scan, known as a dating scan, usually occurs in the first trimester, between 7 and 13 weeks of gestation. This early ultrasound confirms the pregnancy, determines the baby’s gestational age, and establishes a precise due date. It also verifies the pregnancy’s location to rule out an ectopic pregnancy and checks for multiple fetuses.
The second routine ultrasound, commonly called the anatomy or anomaly scan, is typically performed in the second trimester, between 18 and 22 weeks. This detailed scan evaluates the baby’s developing organs and structures for normal development. During this scan, the sonographer examines the baby’s brain, heart, spine, kidneys, and limbs, and assesses the amount of amniotic fluid and the placenta’s position.
Reasons for Additional Ultrasounds
While two ultrasounds are common for uncomplicated pregnancies, additional scans may be recommended for specific medical reasons. These extra ultrasounds are not routine but are performed when there is a clinical need to gather more information or monitor a particular condition.
One common reason for additional scans is a high-risk pregnancy, which can stem from factors such as the pregnant person’s age (e.g., over 40), pre-existing medical conditions like diabetes or high blood pressure, or a history of previous pregnancy complications. Ultrasounds may closely monitor fetal growth if there are concerns about the baby being too small or too large for gestational age. They can also assess the baby’s position, especially as the due date approaches, or check the amount of amniotic fluid.
Additional ultrasounds are also performed to investigate specific symptoms or findings, such as vaginal bleeding, abdominal pain, or reduced fetal movement. If an abnormality is suspected during a routine scan, or if previous tests indicate a potential issue like a placental problem or a structural anomaly, more detailed follow-up ultrasounds are necessary. These scans help healthcare providers track the progression of any identified concerns and guide decisions about ongoing care and delivery planning.
Understanding Ultrasound Safety
Diagnostic ultrasounds are considered safe for both the pregnant individual and the developing baby. This imaging method uses high-frequency sound waves rather than ionizing radiation, which is found in X-rays. The American College of Obstetricians and Gynecologists (ACOG) states there is no evidence that ultrasounds pose a risk to a fetus.
While ultrasound energy has the potential to produce biological effects, studies have not found links between diagnostic ultrasound and birth defects, childhood cancer, or developmental problems. Healthcare organizations recommend that ultrasounds be performed only when medically necessary and by qualified professionals, avoiding non-medical or “keepsake” scans. Although there is a slight temperature increase in tissues with prolonged exposure, routine scans are typically brief and are not associated with harm.
What to Expect During an Ultrasound
During a pregnancy ultrasound, the procedure involves lying on an examination table. A clear, water-based gel is applied to the abdomen, which helps the transducer, a small handheld device, glide smoothly and transmit sound waves effectively. The sonographer moves the transducer across the abdomen, and the sound waves bounce off internal structures, creating real-time images on a screen. This transabdominal approach is common after about 12 weeks of pregnancy.
In earlier stages of pregnancy, particularly before 12 weeks, or if a clearer image is needed, a transvaginal ultrasound may be performed. For this, a thin, lubricated transducer, covered with a protective sheath, is gently inserted into the vagina. While you might feel some pressure, the procedure is not painful. For some abdominal ultrasounds, you may be asked to arrive with a full bladder, as this can improve the clarity of the images. The entire scan usually takes about 30 minutes.