Placenta Previa: Risks, Treatment, and Prognosis

Q: Placenta Previa: Risks, Treatment, and Prognosis

Hello： In response to your question, placenta previa refers to the condition where the placenta is located in the lower segment of the uterus, covering the internal cervical os. <br>Diagnosis relies on ultrasound, and it can be classified into four types based on severity： comple

Placenta previa

Hello Doctor, during my wife's prenatal check-up at 20.5 weeks, the doctor mentioned a tendency for placenta previa, as part of the placenta is covering the cervix.
The doctor advised to observe for four weeks (until 24 weeks) and to perform another ultrasound, as there is a possibility that the placenta may move upward and become normal.
What is the likelihood of this happening? What are the possible treatments or risks involved? Thank you for your valuable response, Kevin.

kevin, 30~39 year old female. Ask Date: 2004/01/07

Dr. Wang Jionglang reply Obstetrics and Gynecology

Hello: In response to your question, placenta previa refers to the condition where the placenta is located in the lower segment of the uterus, covering the internal cervical os.
Diagnosis relies on ultrasound, and it can be classified into four types based on severity: complete placenta previa, partial placenta previa, marginal placenta previa, and low-lying placenta.
Typically, placenta previa should be diagnosed after 28 weeks of gestation, as in early pregnancy the placenta often occupies a large portion of the uterine cavity, and it may still migrate upward before 34 weeks of gestation.
Therefore, unless there is early antepartum vaginal bleeding, close monitoring is recommended according to the current gestational age.
If placenta previa is confirmed, the pregnant woman must adhere to strict bed rest.
If the bleeding is minimal and neither the fetus nor the mother is affected, it may be possible to wait until the fetus matures before delivery.
Since the bleeding originates from open blood vessels in the placenta, which belong to the mother, small amounts typically do not have an immediate impact on the fetus.
It is important to note that complete and partial placenta previa can lead to significant bleeding during labor, so delivery should be via cesarean section.
Additionally, there is a higher risk of postpartum hemorrhage, and in some cases, an emergency hysterectomy may be necessary to control bleeding, especially in cases of placenta accreta.

Reply Date: 2004/01/07

More Info

Hello Kevin,
Thank you for your question regarding placenta previa, which is indeed a significant concern during pregnancy. Placenta previa occurs when the placenta is positioned low in the uterus and partially or completely covers the cervix. This condition can lead to complications during pregnancy and delivery, so understanding the risks, treatment options, and prognosis is essential.

Normal Probability of Resolution:
In many cases, especially when diagnosed early in pregnancy, there is a good chance that the placenta will move away from the cervix as the uterus expands. Studies indicate that approximately 90% of women diagnosed with low-lying placenta or partial placenta previa in the second trimester will see the placenta migrate upward by the third trimester. Therefore, your doctor’s recommendation to monitor the situation with a follow-up ultrasound at 24 weeks is standard practice.
Risks Associated with Placenta Previa:
The primary risks associated with placenta previa include:
1. Bleeding: As the cervix begins to efface and dilate in preparation for labor, the placenta can be torn, leading to significant bleeding. This can be dangerous for both the mother and the baby.

2. Preterm Birth: If bleeding occurs, it may necessitate an early delivery, which can pose risks to the baby, including respiratory issues and developmental delays.

3. Cesarean Delivery: Most women with complete placenta previa will require a cesarean section to avoid complications during vaginal delivery. This is because the placenta obstructs the birth canal, making vaginal delivery unsafe.

4. Postpartum Hemorrhage: Women with placenta previa are at a higher risk for excessive bleeding after delivery, which can sometimes require surgical intervention.

Treatment Options:
The management of placenta previa typically involves:
- Monitoring: Regular ultrasounds to assess the position of the placenta and the health of the fetus.

- Activity Modification: Depending on the severity of the condition and any bleeding, your doctor may recommend reduced activity or bed rest.

- Delivery Planning: If the placenta remains low-lying or covers the cervix as you approach term, your healthcare provider will likely recommend a planned cesarean delivery, usually around 36-37 weeks, to minimize risks.

Prognosis:
The prognosis for women with placenta previa is generally good, especially with appropriate medical care. If the placenta moves away from the cervix, many women can have a normal delivery. However, if it does not resolve, careful planning and management can lead to successful outcomes for both mother and baby.

In conclusion, while the diagnosis of placenta previa can be concerning, it is important to follow your healthcare provider's recommendations and attend all scheduled follow-up appointments. This will ensure that both you and your baby are monitored closely, and any necessary interventions can be made in a timely manner. If you have further questions or concerns, don’t hesitate to reach out to your healthcare provider for personalized advice.

Wishing you and your family all the best during this time!

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