This ultrasound assessment is offered at this stage because the baby has grown enough and is easier to assess with good accuracy its internal organs. There is a systematical examination of all the embryo’s structures as regards its morphology and measurements. This includes examination of the brain and the skull, the face, the chest and the lungs, the heart and its blood vessels, the abdominal wall and viscera, the morphology of urinary and genital tract in boys and girls, the upper and lower limbs, and the spine. Also there is the opportunity to look at the fetus for the presence of sonographic markers (soft markers). Their presence alters the likelihood of chromosomal abnormalities. Such markers are a short femur or humerus, echogenic foci in the heart, mild hydronephrosis, choroid plexuses in the fetal brain, echogenic bowel, shorth nasal bone or increased nuchal fold. However the majority of embryos that exhibit one or more sonographic markers are usually healthy fetuses. But as these markers are often present in fetuses with chromosomal abnormalities, their presence alter the risk that was given at the time of the nuchal translucency in the first trimester.
At this examination it is also checked the position of the placenta, the amount of amniotic fluid. The length of the cervix is measured, a short cervix can indicate if the mother is at risk for premature birth. We carry out also at this stage the Doppler of uterine arteries that can show us whether this pregnancy has an increased risk of developing preeclampsia or intrauterine growth restriction. By this ultrasound examination many congenital abnormalities are detected, but not all of them. We should emphasize that when no abnormalities are detected by this ultrasound examination the risk of the baby having an anatomical problem reduces significantly, but it is not eliminated.