The placenta is the organ that receives all the substances the baby needs from the mother and transmits them to the baby via the umbilical cord, and ensures that all waste from the baby is passed to the mother via the umbilical cord and is expelled. In normal pregnancies, the placenta attaches to the walls and upper parts of the uterus. If the placenta is placed in the lower segment of the uterus it is diagnosed as Placenta Previa. Depending on the relation of the internal cervical os, it is named as complete, partial, marginal or low lying where it completely or partially covers the cervix. Although placentas that are located close to the cervix are called low-lying placenta, this condition usually does not cause serious problems since the placenta moves upwards with the uterus as the pregnancy progresses.
In cases of placenta previa, since the placenta covers the cervix, normal birth, i.e. vaginal birth, would not be possible. Therefore, in cases of placenta previa, a cesarean section would be required. In cases of placenta previa, the placenta can move deeper than normally should (into the muscle layer of the uterine wall and even outside the uterine wall). This condition is called placenta acreata, placenta percreata or generally placenta acreata spectrum (PAS). Both placenta previa and placenta acreata are risk factors for serious bleeding. Especially if the two problems are together, the risk of bleeding is even higher. In these cases, there is a risk of processes that may lead to removal of the uterus. Therefore, placenta previa, whether alone or together with PAS, is a pregnancy problem that can cause fatal bleeding and should be managed seriously.
During normal placental formation and placement on the uterine wall, the cells that form the placenta move from the endometrium to the uterine wall and stop moving when they reach an area with sufficient oxygen. Although the exact cause of placenta previa is not known, we do have evidence for risk factors of placenta previa. Previous interventions into the uterus (curettage, cesarean section, myomectomy), advanced maternal age and multiple births, having had placenta previa in previous pregnancies, and smoking are reported as risk factors for the development of placenta previa. The reported frequency of placenta previa worldwide can reach two percent.
Pregnant women with placenta previa may have the risk factors described above and this can be suspected from the patient's history. Their history also typically includes bleeding that starts suddenly and occurs without any pain. The bleeding is painless and in the form of fresh, light pink blood. In cases of placenta previa, bleeding can be minimal or very severe and can endanger the life of both the mother and the baby. Therefore, it is recommended that the placenta previa cases immediately apply to a fully equipped hospital emergency obstetrics and gynecology service as soon as bleeding begins.
In the case with the above story, fresh blood is seen coming from the vagina during speculum examination. Since digital examination of the cervix may increase the bleeding and worsen the current situation, it is absolutely necessary to avoid digital examination. In transvaginal ultrasonography, the placenta covering the inner opening hole of the cervix can be seen with all its borders and ultrasonography is usually sufficient for diagnosis. Transvaginal ultrasonography provides more information than transabdominal (from the abdomen) ultrasonography. In very rare cases and to understand whether there is PAS (placenta acreata spectrum), magnetic resonance (MRI) may be required.
In a pregnant woman diagnosed with placenta previa, the definitive treatment is delivery and removal of the placenta. Although it is so easy to express, if the week of pregnancy when bleeding occurs is still early in pregnancy and the baby is not mature, the decision to deliver will be postponed until as late as possible - keeping the protection of the mother and baby's life in the foreground-. Cases diagnosed with placenta previa are hospitalized until their condition is fully understood and stabilized. Preparations should be made for blood transfusion in case of excessive blood loss due to bleeding. If the pregnancy is at term, the treatment will be completed with a cesarean section and complete removal of the placenta.
If the pregnancy is early (far from term) and bleeding has stopped, the aim is to reach the term with close monitoring. If there is bleeding that is so severe that it puts the mother's life at risk during monitoring and does not stop, then premature birth may be on the agenda. Depending on pregnancy week, birth may be considered after the necessary approaches are made for the baby's lung development and brain protection.
Since the risk of bleeding is high in cases of placenta previa, and especially in the presence of PAS together with previa, the risk of bleeding will increase even more, so the birth should be planned in a fully equipped hospital and in a center with experienced physicians in this regard. Since the cervix is covered by the placenta, the delivery method must be a cesarean section. Since blood transfusion will be required due to bleeding, sufficient blood products should be kept ready. In cases of placenta previa and PAS together, if the bleeding cannot be stopped and conservative approaches do not work, both the patient and their relatives as well as the surgery and anesthesia team should be informed that a process leading to removal of the uterus may occur and they should be prepared for this scenario.
Placenta previa is a condition that can indicate a process would lead to removal of the uterus, prematurity and long-term problems related to prematurity, and even death of the mother and newborn. All the conditions listed above should be carefully evaluated and pregnant women should be closely monitored from the first diagnosis until treatment completed. The aim is for the pregnancy to reach term, but in cases of placenta previa, delivery is often premature. The issue of how early premature delivery will occur is completely related to the course of placenta previa. If there is a very noisy picture, a decision to deliver can be made immediately, while in cases where the bleeding is very little or has stopped, follow-up can be aimed at least until the 36th week. The main factor that determines the decision to deliver would be pregnancy week and the conditions of the mother and the baby.
