(USMLE topics, obgyn) Low lying placenta or Placenta Previa: pathology, risk factors, complication, diagnosis and treatment.

Purchase a license to download a non-watermarked copy of this video on AlilaMedicalMedia(dot)com

©Alila Medical Media. All rights reserved.
Voice by: Ashley Fleming

All images/videos by Alila Medical Media are for information purposes ONLY and are NOT intended to replace professional medical advice, diagnosis or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.

The placenta is the organ that connects the fetus, via the umbilical cord, to the uterine wall of the mother. This is where the exchange between maternal and fetal blood takes place. The placenta provides the fetus with oxygen and nutrients and takes away waste such as carbon dioxide. Normally, it attaches at the top or side of the uterus. At birth, it is delivered AFTER the baby, in the third stage of labor.
Placenta previa, or sometimes referred to as LOW-lying placenta, is a pregnancy complication in which the placenta attaches to the LOWER end of the uterus, NEAR or COVERING the cervical opening. Placenta previa can be classified as complete or marginal.
The main symptom is painless bleeding in the second half of pregnancy. As the lower part of the uterus gradually THINS in preparation for the onset of labor, placental attachment is disrupted resulting in bleeding.
Risk factors for development of placenta previa include:
- previous pregnancies
- previous surgeries of the uterus
- previous placenta previa
- carrying more than one fetus
- maternal age of 35 or older
- smoking and cocaine use
The location of the placenta is usually checked during a routine ultrasound mid-pregnancy, but a low-lying placenta at this point may NOT be a cause for concern. In most cases, the placenta grows toward the richer blood supply in the upper uterus as the uterus expands in the third trimester. Only about 10% of all low-lying placentas persist until delivery. A placenta that completely covers the cervix is more likely to stay that way than one that's bordering it.
Placenta previa presents significant risks to both the mother and the baby. A cesarean delivery is usually indicated because the placenta may block the birth canal completely, or bleed profusely during labor as the cervix dilates. The mother may experience excessive blood loss and the baby may suffer from hypoxia as a result of INadequate blood supply.
The goal of treatment is to manage bleeding to get as close to the due date as possible. In case of little or no bleeding, bed rest and pelvic rest are recommended. Heavy bleeding is an emergency and might require a blood transfusion. If delivery is necessary before 37 weeks, corticosteroids may be given to help the baby's lungs develop. An uncontrollable bleeding would require an emergency C-section even if the baby is premature.

свернуть