Placenta previaDefinitionPlacenta previa is a rare condition in which the placenta grows in the lower part of a pregnant woman's uterus and covers all or part of the cervix. The placenta is the organ that nourishes the developing fetus. CausesPossible causes of placenta previa include:
Placenta previa is very rare. The risk increases with each pregnancy, especially in women who have had six or more deliveries. The rate of placenta previa is also higher in women who are carrying more than one baby (multiple pregnancy). Risk factors include:
Symptoms
Note: Bleeding may not occur until after labor starts in some cases. Labor sometimes starts within several days after heavy vaginal bleeding. Exams and TestsThe uterus is usually soft and relaxed. In a small number of cases, the infant is in an unusual position. Fetal distress doesn't usually occur unless there is a cord accident, or vaginal blood loss has been heavy enough to cause placenta abruptio or shock in the mother. An abdominal ultrasound during the second trimester can show whether the placenta is low. Transvaginal or transperineal ultrasound can help the doctor see the position of a low-lying placenta. TreatmentTreatment depends on the amount of abnormal uterine bleeding, whether the fetus is developed enough to survive outside the uterus, the amount of placenta over the cervix, the position of the fetus, the number of previous births (parity) for the mother, and whether the mother is in labor. Early in pregnancy, transfusions may be given to replace blood the mother has lost. The mother may get medications to prevent premature labor, and continue the pregnancy to at least 36 weeks. Beyond 36 weeks, the benefits of the infant maturing have to be weighed against the possibility of a major hemorrhage. Cesarean section is the delivery method for placenta previa. It is the most important way to reduce mother and infant death rates. Outlook (Prognosis)The outcome is excellent when the condition is managed properly. This means hospitalizing a mother who is having symptoms, and delivering by C-section. Possible ComplicationsRisks to the mother include:
The risks of infection and blood clots (thromboembolism) also increase, as does the likelihood that the mother will need a blood transfusion. Prematurity (infant is less than 36 weeks gestation) causes most infant deaths in cases of placenta previa. Fetal blood loss or hemorrhage may occur because the placenta separates from the wall of the uterus during labor. The fetus also can lose blood when the uterus is opened during a C-section delivery. When to Contact a Medical ProfessionalCall your health care provider if you have bleeding from the vagina at any point in your pregnancy. Placenta previa can be dangerous to both you and your baby. PreventionThis condition is not preventable. Illustrations and Images
Review Date:
8/17/2007 Reviewed By: Melanie N. Smith, M.D., Ph.D., Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-
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