• What Is Placenta Previa?
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|What Is Placenta Previa?
The placenta is the pan-caked shaped organ that supplies blood and oxygen to your growing baby through the umbilical cord. It is normally located near the top of the uterus (womb). If you have placenta previa it means that the placenta is positioned lower than usual and is close to the cervix. If the placenta is found low in early pregnancy it usually does not cause a problem. As the pregnancy progresses the placenta is likely to 'migrate' further away from the cervix. If it is close to the cervix later in pregnancy it can cause bleeding (hemorrhaging) and other complications. You may need to deliver early by cesarean section. Placenta previa is not very common, it occurs in about 1 in every 200 pregnancies. There are several factors which increase your risk:
There are different types of placenta previa:
The main sign is sudden painless bleeding from the vagina. Bleeding:
Whenever there is bleeding in late pregnancy, placenta previa or placenta abruption is suspected. An ultrasound scan can diagnose either condition. A manual pelvic examination should never be performed because it could prompt a life-threatening hemorrhage. In most instances placenta previa is diagnosed during a routine mid-pregnancy ultrasound (anatomy scan, week 18-22). There may be no symptoms this early. If you are diagnosed, try not to panic. In most instances as the pregnancy progresses the placenta migrates back up the womb and the problem is resolved. You will receive a third trimester ultrasound as a follow up to check the location. If you have any bleeding in the meantime, an ultrasound will be performed to see what is going on. Only a small percentage of women with low lying placentas at week 20 still have them by the time they deliver their baby. With complete placenta previa, the position is not likely to improve.
In the situation where there is uncontrolled bleeding, an emergency cesarean section is performed. But more commonly, the woman is admitted to hospital when bleeding has only been slight and there is still time to check the position of the placenta by ultrasound. At this point the doctor will carefully weigh up the risks of further bleeding against delivery of the baby. After 36 weeks delivery may be the best treatment. Before this, you will be recommended:
Women with total placenta previa, or with any kind of placenta previa accompanied by heavy bleeding must be delivered by c-section. This is because delivery is faster by c-section and results in less blood loss. However, women with marginal or low lying placenta previa who have had children before, and are well into labor (cervix dilated at least 4cm) may have a simple vaginal delivery. For this to happen the bleeding should not be severe, there should be no sign of fetal distress and the delivery needs to be imminent. These conditions apply to about 50 percent of all cases.
The major danger of placenta previa to the baby is premature delivery before major organs such as the heart and lungs have had time to fully mature. As a result, hospitalization in a center with neonatologist or perinatologist specialized care will ensure the best care for your baby if he is born early. Placenta previa has also been linked to intrauterine growth restriction (IUGR). The biggest risk to the mother is severe bleeding and blood loss.
Vasa previa is a rare cause of antepartum bleeding and occurs when one or more of the baby's placenta or umbilical cord vessels crosses the entrance to the birth canal under the baby. When the cervix dilates or the membranes rupture for birth, the vessels can tear causing rapid fetal blood loss. Blood loss associated with placenta previa comes from the mother but with Vasa previa, the blood loss is from the baby. The baby is starved of oxygen and the mortality rate (if not diagnosed early enough) is 95 percent. Vasa previa can be seen in a routine anatomy scan.
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