401072 Lecture Notes - Lecture 2: Rh Disease, Gestational Sac, Congenital Disorder
Document Summary
Obstetric ultrasonography is routinely used for dating the gestational age of a pregnancy from the size of the fetus, determine the number of fetuses and placenta. , evaluate for an ectopic pregnancy and rst trimester bleeding, the most accurate dating being in rst trimester before the growth of the foetus has been signi cantly in uenced by other factors. Ultrasound is also used for detecting congenital anomalies (or other foetal anomalies) and determining the biophysical pro les (bpp), which are generally easier to detect in the second trimester when the foetal structures are larger and more developed. Specialised ultrasound equipment can also evaluate the blood ow velocity in the umbilical cord, looking to detect a decrease/absence/reversal or diastolic blood ow in the umbilical artery. X-rays and computerised tomography (ct) are not used, especially in the rst trimester, due to the ionising radiation, which has teratogenic effects on the foetus.
