Nursing 209

N209: Reproductive Health Study Guide o Oxygenated blood goes through the patent foramen ovale from the right atrium to the left atrium and then to the left ventricle and out the aorta o Allows the best oxygenation to the brain • Ductus Arteriosus o Unoxygenated blood also enters the right atrium to the right ventricle, but bypasses the lungs through the ductus arteriosis • Both the patent foramen ovale and patent ductus arteriosus are normal in fetal circulation o Allows babies with heart defects to survive and not be affected until after birth when they begin to close o At birth, the clamping of the umbilical cord stops oxygen and nutrients from the mother o With onset of breathing, lungs expand and patent foramen ovale and ductus arteriosus close o Patent ductus arteriosus after birth leads to abnormal blood flow o Patent foramen ovale occurs in one in five adults o Incomplete closure can result in blood flow directly from the right atrium to the left, bypassing the lungs filtration o Usually not diagnosed until there is a TIA Also referred to as uteroplacental circulation • Not fully established until the end of the first trimester • Maternal blood enters the placenta through the endometrial arteries • Perfusion occurs in the intervillous spaces; exchange of oxygen and nutrients takes place with fetal blood • Return occurs via uterine veins Abnormal Cord Insertion • 90% of umbilical cord insertion occurs on fetal surface (chorionic) of the placenta • Normal cord length is 40-70 cm Abnormal Cord Conditions • Velamentous insertion • Marginal insertion • True knot in cord 3.12 Maternal-Placental Circulation •

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