• A condition in which the placenta covers or is within 1 cm of the cervical os.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• Abnormal placentation in which the PLACENTA implants in the lower segment of the UTERUS (the zone of dilation) and may cover part or all of the opening of the CERVIX. It is often associated with serious antepartum bleeding and PREMATURE LABOR.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• Placenta previa is implantation of the placenta over or near the internal os of the cervix. Typically, painless vaginal bleeding with bright red blood occurs after 20 weeks gestation. Diagnosis is by transvaginal or abdominal ultrasonography. Treatment is modified activity for minor vaginal bleeding before 36 weeks gestation, with...
  Merck Manuals
  Merck & Co., Inc., 2020
• Placenta previa is an obstetric complication that classically presents as painless vaginal bleeding in the third trimester secondary to an abnormal placentation near or covering the internal cervical os. However, with the technologic advances in ultrasonography, the diagnosis of placenta previa is commonly made earlier in pregnancy.
  Medscape
  WebMD, 2019
• The placenta is a structure that develops inside your uterus during pregnancy, providing oxygen and nutrition to and removing wastes from your baby. The placenta connects to your baby through the umbilical cord. In most pregnancies, the placenta attaches at the top or side of the uterus.
  Mayo Clinic
  Mayo Foundation for Medical Education and Research
• Placenta previa (PP) is defined as the placenta overlying the cervical os. It can be complete, partial, marginal, or low lying. Partial, marginal, and low-lying PP may resolve as pregnancy progresses. In women with a scarred uterus (most commonly from a prior cesarean section), PP may be associated with an abnormally adherent placenta,...
  Epocrates
  Athenahealth, Inc., 2019
• Placenta praevia, implantation of the placenta at a point so low in the uterus that the placenta is close to the opening into the cervix or covers the opening, either partially or completely. The placenta is the temporary organ that develops during pregnancy to nourish the fetus and to carry away...
  Encyclopedia Britannica
  Encyclopedia Britannica, Inc., 2020