What is placenta posterior wall lower uterine segment?

Question

You have not mentioned how many weeks you r pregnant. The placenta can be situated anywhere on the surface of the uterus. The front wall is called anterior. The back wall is called posterior. In about 5% of routine 18 - 20 week pregnancy ultrasounds, the placenta is seen to be lying low. Meaning the placenta is situated lower in the uterus, closer to the woman's cervix. A low-lying placenta at this stage of pregnancy is regarded as normal because the lower segment of the uterus has not fully formed yet. The lower segment of the uterus starts forming at around the 24th week of pregnancy, and is fully present by 36 weeks. During this time, the uterus slowly stretches upwards, forming the thicker upper segment and leaving a thinner layer of muscle below it, known as the lower segment. The lower segment separates the cervix from the upper segment and is the part of the uterus that absorbs the cervix as it dilates during labour. In about 90% of cases, the previously low-lying placenta moves up into the upper segment as the uterus grows, meaning that by about the 34th week it is no longer low-lying.

Karuna Chawla · Accepted Answer

You have not mentioned how many weeks you r pregnant. The placenta can be situated anywhere on the surface of the uterus. The front wall is called anterior. The back wall is called posterior. In about 5% of routine 18 - 20 week pregnancy ultrasounds, the placenta is seen to be lying low. Meaning the placenta is situated lower in the uterus, closer to the woman's cervix. A low-lying placenta at this stage of pregnancy is regarded as normal because the lower segment of the uterus has not fully formed yet. The lower segment of the uterus starts forming at around the 24th week of pregnancy, and is fully present by 36 weeks. During this time, the uterus slowly stretches upwards, forming the thicker upper segment and leaving a thinner layer of muscle below it, known as the lower segment. The lower segment separates the cervix from the upper segment and is the part of the uterus that absorbs the cervix as it dilates during labour. In about 90% of cases, the previously low-lying placenta moves up into the upper segment as the uterus grows, meaning that by about the 34th week it is no longer low-lying.