be broken by collagenase associated w/ ascending infection
implantation of the placenta over or near the internal cervical os so that it encroaches on a portion of the dilated cervix.
classified as total, partial, or marginal; sometimes include low lying placenta
separation of a normally implanted placenta before the delivery of the fetus.
initiated by hemorrhage into the decidua basalis with formation of a hematoma
Possible causes: maternal hypertension, compression or occlusion of the inferior vena cava, circumvallate placenta, or trauma.
The incidence of abruptio placentae is markedly increased with maternal cocaine use b/c induce vasoconstriction of placental blood
vessels and a sudden elevation in maternal blood pressure.
placental implantation w/ abnormally firm adherence of all or part of the placenta to the myometrium.
Increta: villi invade the myometrium
Percreta: penetrate through the myometrial wall
Associated with placenta previa, particularly in the presence of a uterine scar, and with significant morbidity including severe hemorrhage, uterine perforation, infection, and hysterectomy.
circumvallate placenta: the area of the chorionic plate is reduced. As chorionic
villi invade the decidua, the fetal membranes fold back upon themselves, creating a dense, grayish-white raised ring encircling the central portion of the fetal surface. The fetal vessels forming the cord stop at this ring rather than covering the entire fetal surface of the placenta.
--> increased risk for abruptio placenta
Marginate (or circumarginate) placenta: also arise from a chorionic plate that is smaller than the basal plate. In these placentas the white ring composed of the fetal membranes coincides with the margin of the placenta, without the folding back of the membranes seen in circumvallate placentas
development of one or more smaller accessory lobes in the membranes attached to the main placenta by fetal vessels.
The accessory lobes may be retained, leading to postpartum hemorrhage or infection. These placentas are often associated with malrotation of the implanting blastocyst with velamentous insertion of the cord.
single uterine artery
associated with an increased incidence of fetal
cardiovascular and urinary tract anomalies
insertion of the cord at or within 1.5 cm of the margin of the placenta
may be clinically benign but has been linked to preterm labor, fetal distress, and bleeding in labor due to cord compression or vessel rupture.
cord inserts into the membranes so that the vessels run between the amnion and chorion before entering into the placenta.
More common in multiples
may lead to rupture and fetal hemorrhage
associated with a high fetal mortality, particularly with vasa praevia