Your first pregnancy ultrasound... you’ve pictured in your head: the gel on your belly, the doctor running what looks like a price scanner from the grocery store over your bump, magically transmitting an image of your little baby onto a video screen. So the day has finally come, and the doctor comes into the room. She asks you to place your feet in the stirrups, and she gets out a wand looking thing, and a condom. Wait-- you think, what the???
Ultrasound is based on the same technology used for sonar. Sound waves are bounced off objects, and the echoes are translated into images based on the distance the echo travels, and the types of tissue the sound waves hit. These sound waves transmit particularly well through soft tissue and water, so ultrasound is very useful during pregnancy, allowing health care practitioners to see the developing fetus in the amniotic fluid filled sac.
There are two types of ultrasound that are most commonly used in obstetricians’ offices. The first, transabdominal, is the one you probably picture in your mind, see on TV, movies, etc. A gel is squirted on your bare belly, allowing for better conductivity. The transducer is run over your abdomen, sending the sound waves through the soft tissue and muscle, and the echoes it sends back are translated into a 2D image on the video screen. It’s the same type of technology used in underwater sonar. This type of ultrasound is sufficient for a check up of a normal, healthy baby.
A transvaginal ultrasound takes a different approach, so to speak. A sterilized wand, (about as the size of your average tampon with applicator), is inserted into the vagina, allowing closer proximity to the uterus, (my OB always puts a condom over the wand for hygienic purposes). The closer the transducer is to the uterus, the higher frequency sound waves can be used. This type of frequency creates a clearer image on the screen. Some doctors prefer this type of ultrasound due to its superior image. This clarity can be useful in seeing details, or screening for abnormalities.
Both procedures are painless (the gel can be a little cold), and are harmless to your pregnancy. There is a third type of ultrasound that can be used by doctors as a more detailed diagnostic tool: the 3D ultrasound. This ultrasound has also gained popularity with soon to be parents, as it gives a clear photographic like view of the baby in utero. I will give more information on that in my next post.