Pharm D
Placenta previa occurs in one in five women. If not managed with the right approach, it can lead to fatal outcomes.
Placenta previa is a condition in which the placenta attaches in the lower segment of the uterus over or near the internal os of the cervix. The placenta exchanges nutrition and oxygen between the mother and the fetus. As the pregnancy progresses, it gets highly vascularized because of the increased baby demands.
Under normal conditions, the placenta implants itself in the upper portion of the uterus or the body. This helps in delivering the baby first and then the placenta. With placenta previa, as the uterus contracts and the cervix dilates, the placenta villi begin to tear away from the uterine wall, leading to painless, bright red vaginal blood. The bleeding because of placenta previa can occur in antepartum or intrapartum. Placenta previa can cause hemorrhage in the postpartum period because the lower segment of the uterus contracts poorly compared to the fundus and body of the uterus.
Depending on the degree of placental encroachment, placenta previa can be classified into four types:
The placenta is low-lying when it implants in the lower uterine segment but does not reach the cervical os. In most cases, the low-lying placenta often moves upward as the pregnancy progresses. That eliminates the bleeding complications in the later stages and allows a vaginal delivery.
In the marginal placenta, its edge is at the edge of the internal os. With that, the mother can deliver the baby vaginally.
The partial placenta previa covers the cervical os, and with the progression of pregnancy, it leads to vaginal bleeding because of cervical dilation.
In total placenta previa, the placenta covers the cervical os completely, and often, the mother requires an emergency cesarean section with it.
The exact cause of placenta previa is unknown. However, it is more common among women with a history of uterine surgeries, such as previous C-sections or dilation and curettage. The risk is also increased in women having infections with endometritis and a history of previous placenta previa.
Moreover, the occurrence of placenta previa is more common in women who are currently pregnant with twins or more babies with a large placenta.
How Placenta Previa Is Diagnosed
For a pregnant woman bleeding through the vagina, vaginal exams are contraindicated. An ultrasound helps rule out placenta previa. For diagnosing the placenta previa, the following tools are helpful:
Transvaginal ultrasound is preferred, but transabdominal ultrasound is also done. In normal conditions, placental implantation is visualized in the fundus of the uterus. When the placenta is abnormally attached, it is visualized in the lower uterine segment. Visualization of the placenta helps determine its location and can also diagnose other causes of bleeding, such as placental abruption, cervical lesion, or excessive show.
Blood checks, such as red blood cell count, serum hemoglobin, and hematocrit, help rule out if a patient is bleeding because of placenta previa. Red blood cell count decreases several hours after blood loss has occurred. The average blood count is 4–5.4 mL/mm3. With vaginal bleeding, the levels significantly drop. Hemoglobin and hematocrit also decrease with active bleeding having normal ranges of 12–16 g/dL and 37%–47% respectively.
Nursing Implementation
Managing patients with placenta previa depends on the health status of the mother and the amount of bleeding that has already happened. Moreover, it also depends on the fetus’s gestational age and health status.
If the mother and her baby are stable and the fetus is less than 37 weeks old, the delivery may be put off, and the mother is given intravenous lactated Ringer’s solution. Ask the patient to do complete bed rest and not exert any effort. With that, continuous electronic fetal monitoring is performed. Keep a keen eye on the fetal heart rate. If you notice any signs of fetal distress such as tachycardia, bradycardia, late decelerations, or flat variability, turn the mother on her left side and increase the IV infusion rate of lactated Ringer’s solution with oxygen via face mask at 10 liters per minute and notify the physician soon.
You can discharge the patient from the hospital once the bleeding stops for at least 24 to 48 hours. However, ask them to maintain complete bed rest at home and not to lift heavy objects. In the meantime, the fetus can mature, and delivery can occur as soon as possible. With a marginal placenta, the physician often allows delivery vaginally with close surveillance of the mother and the fetus’s health throughout the labor.
In the postpartum period, administer oxytocin to prevent hemorrhage because of the poor ability of the lower uterine segment to contract. If the fetus is in distress and the mother has lost a significant amount of blood, it leads to immediate cesarean section and blood transfusions if indicated and possible.
With placenta previa, whether the woman delivers vaginally or through a cesarean section, monitor her for signs of postpartum hemorrhage because the contraction in the lower uterine segment may not be effective enough in compressing the blood vessels of the uterus exposed at the placental site.
As such, no medication is given for placenta previa; magnesium sulfate can help to stop preterm labor if it is happening and bleeding is under control. Moreover, enhance fetal maturity with betamethasone injections to the mother if delivery is expected prematurely and RhD immunoglobulins to prevent Rh disease when the patient delivers.
Increased Risks
Women with placenta previa are at increased risk of complications and hysterectomy. You must inform the possible complications and outcomes of placenta previa to the woman before delivery, so they are mentally prepared.
During bed rest, place cushions on the patient’s backside to comfort them. Back rubs can also be helpful, as prolonged bed rest can cause backache. Also, please provide them with emotional support and diversional activities that help divert their minds. Ask them to watch something on the phone or read a book to keep themselves busy.
As a nurse, explain the condition, treatment, and potential outcomes to the patient. In most cases, preterm delivery is unavoidable. Inform the nursery nurse to explain to the mother if the baby has to be kept in the neonatal ICU when born preterm.
Placenta previa is when the placenta attaches abnormally to the uterus and may or may not cover the cervical os. The condition needs close monitoring, regular checkups, and long-term bed rest. Ask your patient to attend follow-up visits and maintain complete bed rest until the physician sees that the condition has improved. Inform the patient that not adhering to bed rest can lead to life-threatening bleeding and fatal consequences.
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