| placenta previa | <obstetrics> The anatomic positioning of the placenta over the cervical os (opening to the birth canal). This is an important cause of painless third trimester bleeding in the pregnant female. Many cases of placenta previa will require cesarean section delivery. (31 Dec 1997) |
|---|---|
| placenta previa centralis | Placenta previa in which the placenta entirely covers the internal os of the cervix. Synonym: central placenta previa, total placenta previa. (05 Mar 2000) |
| placenta previa marginalis | Placenta previa in which the placenta comes to the margin of, but does not occlude, the internal os of the cervix. (05 Mar 2000) |
| placenta previa partialis | Placenta previa in which the internal os of the cervix is partially covered by placental tissue. (05 Mar 2000) |
| placenta protein | human placental lactogen |
| placenta reflexa | An anomaly of the placenta in which the margin is thickened so as to appear turned back upon itself. See: placenta circumvallata, placenta marginata. (05 Mar 2000) |
| placenta reniformis | A kidney-shaped placenta. (05 Mar 2000) |
| placenta spuria | A mass of placental tissue which has no vascular connection with the main placenta. (05 Mar 2000) |
| placenta triloba | A placenta consisting of three parts almost entirely separate, being joined together only by the blood vessels of the umbilical cord; the foetus is single. Synonym: placenta triloba, placenta triplex. (05 Mar 2000) |
| placenta tripartita | A placenta consisting of three parts almost entirely separate, being joined together only by the blood vessels of the umbilical cord; the foetus is single. Synonym: placenta triloba, placenta triplex. (05 Mar 2000) |
| placenta triplex | A placenta consisting of three parts almost entirely separate, being joined together only by the blood vessels of the umbilical cord; the foetus is single. Synonym: placenta triloba, placenta triplex. (05 Mar 2000) |
| placenta uterina | <anatomy> The part of the placenta derived from the uterine tissue. See: placenta. Synonym: maternal placenta, placenta uterina. (05 Mar 2000) |
| placenta velamentosa | A placenta in which the umbilical cord is attached to the adjoining membranes, with the umbilical vessels spread out and entering the placenta independently. (05 Mar 2000) |
| placenta, accessory | An extra placenta separate from the main placenta. Also called a succenturiate or supernumerary placenta. Placenta accreta: the abnormal adherence of the chorionic villi to the myometrium. The vascular processes of the chorion (a foetal membrane that enters into the formation of the placenta) grow directly in the myometrium (the muscular portion of the uterus). Normally there is tissue intervening between the chorionic villi and the myometrium. Here there is not. The word accreta comes from the latin accretio from ad meaning to or toward + crescere meaning to grow. Placenta accreta can progress to placenta percreta. (12 Dec 1998) |
| placenta, low | Location of the placenta in the lower part of the uterus (womb) so that the placenta partially or completely covers the cervix. Also known as a placenta previa. (12 Dec 1998) |