Parents-to-be are generally offered the option of having one or more ultrasounds of their baby over the course of the pregnancy. An ultrasound, also called a sonogram, is typically performed in the hospital or doctor's office during a routine prenatal visit, and can reveal details about the developing fetus that cannot be determined through blood or urine tests of the mother.
Technology
Ultrasound technology works by bouncing sound waves sent from an external probe off the fetus. When the sound waves bounce back, the ultrasound machine interprets the results and forms a visual picture on the monitor. A trained technician performs the ultrasound and can point out a baby's features in the picture, which are usually difficult for untrained individuals to distinguish. An ultrasound machine often has the capability of printing this picture for parents-to-be to take home.
Procedure
The technician first rubs a gel onto the pregnant woman's exposed belly. Then she moves the probe over the abdomen to look at the baby from different angles in order to be able to see all areas of the baby's body. The technician will freeze the picture on the monitor at certain points in order to measure the baby's length, head size and other body parts and to check for specific fetal defects. After the sonogram is complete, the gel is cleaned off and the report sent to the woman's primary obstetrician, who will discuss it with her.
Types
The most common type of ultrasound performed during pregnancy is the traditional 2D ultrasound, which gives a flat picture in black and white. For very early ultrasounds, a transavaginal ultrasound uses a probe inserted into the vaginal canal instead of moved across the woman's abdomen. These are used to bring the ultrasound closer to the tiny embryo of early pregnancy, which is located lower in the pelvis than during later stages. 3D ultrasound is also available, which gives a three-dimensional view of the baby, allowing greater detail to be seen. A 4D ultrasound adds the ability to see movement to a 3D sonogram.
Purpose
Ultrasound is primarily used to look for defects in the fetus, placenta, umbilical cord and amniotic sac. In early pregnancy, it can detect the baby's heartbeat and whether the pregnant woman is carrying one or more babies. Before 12 weeks, a measurement of the baby's size can help determine whether the calculated due date is accurate. After the 16th to 20th week of pregnancy, the baby's gender can be revealed via ultrasound. Ultrasounds throughout pregnancy can be used alone or in comparison with previous ultrasounds to assess fetal growth and the proper development of major organs and limbs. Individuals at risk for genetic or developmental defects may be given a more in-depth ultrasound to look for specific problems such as spina bifida or Down syndrome.
Warnings
Ultrasounds should be carried out by licensed technicians, since untrained operators are more likely to miss potential problems. Parents shouldn't panic about suspicious results, however, since many problems detected via ultrasound can be treated in the womb or immediately after birth as long as they are detected early. Ultrasounds are generally considered safe for the pregnant woman and her baby, and no correlation has been found tying ultrasounds to birth defects or other adverse outcomes. However, the American Academy of Family Physicians warns against "keepsake" ultrasounds performed in a nonmedical setting by untrained technicians, since they may give parents-to-be incorrect information about the health of their baby. According to Kids Health, a website developed by the Nemours Foundation, these keepsake ultrasounds may also endanger the baby if the untrained technicians use higher-powered ultrasound for longer periods of time than are typically considered safe.
