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Placental insufficiency or Utero-placental insufficiency is insufficient blood flow to the placenta during pregnancy. The term is also sometimes used to designate late decelerations of fetal heart rate as measured by electronic monitoring, even if there is no other evidence of reduced blood flow to the placenta, normal uterine blood flow rate being 600mL/min. ==Causes== Placental insufficiency can be induced experimentally by bilateral uterine artery ligation of the pregnant rat. The following characteristics of placentas have been said to be associated with placental insufficiency, however all of them occur in normal healthy placentas and full term healthy births, so none of them can be used to accurately diagnose placental insufficiency: * Abnormally thin placenta (less than 1 cm) * Circumvallate placenta (1% of normal placentas) * Amnion cell metaplasia, (amnion nodosum) (present in 65% of normal placentas) * Increased syncytial knots * Calcifications * Infarcts due to focal or diffuse thickening of blood vessels * Villi capillaries occupying about 50% of the villi volume or when <40% of capillaries are on the villous periphery Placental insufficiency should not be confused with complete placental abruption, in which the placenta separates off the uterine wall, which immediately results in no blood flow to the placenta, which leads to immediate fetal demise. In the case of a marginal, incomplete placental abruption of less than 50%, usually weeks of hospitalization precedes delivery and outcomes are not necessarily affected by the partial abruption. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Placental insufficiency」の詳細全文を読む スポンサード リンク
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