Placental Malperfusion

Abstract

Placental insufficiency is a term often used in connection with placental malperfusion and is sometimes defined as a critical reduction of the placental exchange membrane. It is a most difficult term to define precisely. Ratios of placental to fetal weight have been used to correlate with placental function, but alterations of this ratio are so frequent that one cannot deduce placental dysfunction from an abnormal ratio (see Table 3.7 in Chap. 3). “Placental insufficiency” may be due to a variety of factors including abnormal fetal genome, chronic infection, maternal disease, localization of the placenta in the uterus, cord insertion, preeclamptic changes, chorangiosis, tumors, fetal thrombotic vasculopathy, excessive fibrinoid deposits, and so on. We prefer to specify the lesions that are present rather than to embrace them all in the imprecise terminology of “placental insufficiency.” Placental malperfusion, on the other hand, also has many synonyms, including placental underperfusion, uteroplacental malperfusion, uteroplacental underperfusion, and ­placental bed underperfusion. These all describe the same thing and have in common a number of features, with the primary defect being an abnormality in uteroplacental vessels. These abnormalities and their sequelae are described below.