Transvaginal and transabdominal ultrasounds allow women to see a developing baby or babies in their womb. During the first three weeks after conception, ultrasound technicians can't usually take any measurable images with an ultrasound. Around week four, you can see the gestational sac -- a cocoon-like structure that helps form the placenta. During the fifth week, you can see the tiny fetus, measuring approximately 1/8 to 1/16 of an inch.
Earliest Images of Your Baby
Ultrasounds can detect the earliest images of your baby around five weeks after conception. The fetus is about the size of an ink-pen dot, but technicians can magnify the image using computer software. Most of what you can see is fluid inside the gestational sac. Amniotic fluid -- the fluid your baby lives in throughout your pregnancy -- naturally replaces the gestational sac fluid during the next few weeks. An ultrasound technician should be able to locate a small white circle inside the gestational sac, known as the yolk sac, that provides nutrients to your baby until the placenta develops. Next to the yolk sac is the extremely tiny embryo, typically marked with little plus signs on the ultrasound monitor, according to Parents. Technicians measure the embryo to determine your likely due date.
Around week six, the fetus starts to look much more like a baby. It has a tucked C-shape that curves inward and has a recognizable head and umbilical cord. You can also see small stumps where the arms and legs will continue to grow and develop. The ultrasound technician can also take pictures of the neural tube -- the beginning of brain development -- and the spinal cord. The entire fetus measures approximately 1/6 to 1/4 of an inch. At this stage, blood is pumping through the baby's heart. As early as six to eight weeks, an ultrasound technician can measure your baby's heartbeat and heart rate, according to Advanced Women's Imaging.
Transvaginal Vs. Abdominal Ultrasounds
There are two primary types of ultrasounds used to examine and measure babies during pregnancy -- transvaginal and transabdominal. A transvaginal ultrasound produces the clearest images because the ultrasound probe is inserted in the vagina, close to the developing fetus. Ultrasound technicians conduct transabdominal ultrasounds on the exterior of the abdomen. In both cases, technicians apply a cool lubricating gel to increase visibility and enhance the clarity of the images. Neither ultrasound is painful.
Your physician recommends the type of ultrasound she wants you to get and how frequently she wants to examine the baby using ultrasound technology. She is likely to recommend an ultrasound after eight weeks of gestation when she's sure she can obtain sufficient images and measurements to study your baby's health and verify the expected due date. Many early ultrasounds are transvaginal because they provide clearer pictures of the tiny, developing baby.
Your health insurance might dictate the number of ultrasounds included in your pregnancy plan under normal conditions. For example, your doctor might only recommend abdominal ultrasounds during your second or third trimester if she doesn't have any concerns about your pregnancy. Ask the ultrasound technician if you can have pictures or a video recording of the first images of your baby.