Whether or not it is easy to see the pregnancy sac on an ultrasound does not have much to do with the position of the uterus, so the posterior position of the uterus does not affect the results of an ultrasound, as long as the pregnancy sac is inside the uterine cavity, it is relatively easy to see. Although it can be determined that you are pregnant by testing with pregnancy test paper or taking a blood test, it is not certain that it is an intrauterine pregnancy. An ultrasound is the only way to determine if it is an intrauterine pregnancy and to find out exactly how the embryo is developing. The incidence of ectopic pregnancy is relatively low, but if the ectopic pregnancy can not be detected as early as possible, with the increase of pregnancy sac is getting bigger and bigger, if the lesion rupture, the risk is greater. Some may even jeopardize the life of the pregnant woman, so an ultrasound in the early stages of pregnancy is very necessary. During pregnancy, under the advice of the doctor to do a good job of all the regular checkups during pregnancy, only through a good regular checkups, we can understand the specific situation of the pregnant woman and the fetus. If there is any abnormality in the examination, take appropriate treatment and conditioning measures in time, which is more conducive to the health of the pregnant woman and the growth and development of the fetus.