A Prenatal Ultrasound test uses high-frequency sound waves, inaudible to the human ear, that is transmitted through the abdomen via a device called a transducer to look at the inside of the abdomen. With prenatal ultrasound, the echoes are recorded and transformed into video or photographic images of your baby. The ultrasound can be used during pregnancy to show images of the baby, amniotic sac, placenta, and ovaries. Major anatomical abnormalities or birth defects may be visible on an ultrasound. Most prenatal ultrasound procedures are performed topically, or on the surface of the skin, using a gel as a conductive medium to aid in the image quality. However, a transvaginal ultrasound is an alternative procedure in which a tubular probe is inserted into the vaginal canal. This method of ultrasound produces an image quality that is greatly enhanced. It may be used early in pregnancy to get a clearer view of the uterus or ovaries if a problem is suspected. It can also be used to determine how far along you are in your pregnancy (gestational age). Transvaginal ultrasound is also used to evaluate the cervix for problems such as shortening which may increase your risk of early labor. Ultrasound does not use radiation, as other procedures, such as X-rays, do.
How Should I Prepare for an Ultrasound?
There is no special preparation for the ultrasound test. Some doctors require you to drink 4-6 glasses of water before the test, so your bladder is full. This will help the doctor view the baby better on the ultrasound. You will be asked to refrain from urinating until after the test.