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An ultrasound is a painless test used by doctors to evaluate the state of health of a patient. In pregnant women, the ultrasound is used to evaluate and check on the baby before his birth. To make the ultrasound, the doctor is going to use a plastic device which emits high frequency sound waves through your body. The waves return when they hit a tissue, forming an image on the screen of the ultrasound machine. If you are having a 6 weeks ultrasound the doctor will probably choose to use a vaginal ultrasound machine, which consists of the insertion of a long wand into your vagina. The traditional method might not be useful, because the pregnancy is in its early development stage, thus, very small. This test provides valuable information for the doctor about the baby, without putting your body to unnecessarily stress, which could also stress the baby.
Ultrasounds are used to find abnormalities and other problems in the baby before he is born and it’s also used to determine the due date, the age of the pregnancy, the positioning and other essential information about your baby. Ultrasounds are also used to determine the sex of the baby.
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When should you have the first ultrasound?
Typically, the first ultrasound is taken at 7 weeks into the pregnancy, but the latest technologies are making a 6 week ultrasound possible. At this age, the baby is not going to be formed, but the doctor will check if there is a pregnancy in the first place and will try to find out if the baby is alive or not.
It’s very hard to detect a heartbeat in a 6 week pregnancy, as the results can be very deceiving. Most doctors ask mothers to be to return for another scan when the pregnancy is more advanced. During this second ultrasound, the doctor can evaluate the changes which took place and see if the embryo is growing as expected.
What can you see?
At your first ultrasound you can’t see a lot, but your doctor will be able to establish a number of important details about your pregnancy.
First, the location of the pregnancy will be visible at the first scan. The test can easily show where the pregnancy is located, which is very important for the future: in the case of an ectopic pregnancy, when the embryo is placed outside the uterus, in the Fallopian tube, the doctor will be able to advise you on what’s best to do next. Ultrasounds show the blood flow, which is another important clue in establishing the exact location of your pregnancy and if you will be able to carry the pregnancy to full term.
The fetal pole is visible at the 6 week ultrasound – this is the shape of the embryo, which is going to develop into your baby. The doctor will measure it and determine its size, then will establish if the fetus is growing as it should, based on the measurements of the fetal pole. During the ultrasound the doctor will also check the inclination of the fetal pole, which is another important feature which helps the medical team establish how healthy the fetus is. The “head” and “feet” of the embryo are also determined on this test.
The most impressive feature detected during this peirod is the baby’s heart beat. At this age, the heart beat ranges between 90 and 110 beats per minute. Depending on the heart beat, your doctor will be able to tell you if the baby is alive and how healthy it is; also, you will be informed if you are going to end the pregnancy on full term or in a miscarriage. However, it’s premature to tell anything for sure at this point. If there is no heart beat detected you might be called to do a second, 7 or 8 weeks ultrasound.
Chorionic sac and yolk sac are two other features which are checked at the first ultrasound. The chorionic sac is the fluid cavity which holds the fetus for the entire pregnancy, while the yolk sac is the source of nutrition for the embryo before the placenta is fully developed and is found inside the chorionic sac, which is called gestational sac. It’s important to check the gestational sac and the yolk sac because at this stage of the pregnancy, the embryo relies on the yolk sac for nutrition as the placenta is not yet developed. The doctor will check the state of the two sacs during the ultrasound, to make sure the embryo has all the resources needed for a healthy development until the pregnancy reaches the state when the baby is fed through the umbilical cord, from the placenta.
Can it fail to reveal the embryo?
Sometimes, the 6 week ultrasound doesn’t shows the embryo or its vital signs. The doctor is mainly concerned about the gestational sac at this test, but he also takes into consideration of there is a heart beat present or not. However, the absence of a heart beat doesn’t mean your baby is not alive.
There are cases when the pregnancy age is not 6 weeks, as you thought, as your only landmark for calculating the age of your pregnancy is estimated on your menstrual cycle, so the doctor will measure the gestational sac, the fetal pole and will evaluate when you are due to give birth. In women who don’t have a regular menstrual cycle, the age of the pregnancy can be off by a week or more. What you think is a 7 week pregnancy might in fact be a 5 week or even younger pregnancy – of course, in these cases, the heart beat can’t be detected, nor the fetal pole, so the doctor will ask for a second test.
Being the earliest test for pregnant women, the test is usually accompanied by other type of tests, because the embryo is in its first development stage and the results of the ultrasound alone might not be conclusive at the moment.