Placenta previa is a pregnancy-related complication where the placenta obstructs part or all of the cervical opening, hindering the baby’s passage through the birth canal. The primary symptom is vaginal bleeding, usually occurring in the latter half of pregnancy. In most cases, individuals with placenta previa require a caesarean section for delivery.

Knowing about this condition is essential for foreseeing possible underlying issues at an early stage, thus reducing the chances of complications. Moreover, learning about this complication is crucial for MBBS and NEET PG aspirants as it is a part of their curriculum and can help them in their future medical careers.  

Read through the guide to understand the types of placenta previa, its possible complications for both the mother and the newborn, and the available treatment modalities.

What is Placenta Previa?  

Placenta previa is a medical condition that occurs when the placenta causes a partial or complete obstruction in the cervix during the later stages of pregnancy. The placenta is a vital organ that forms in the uterus during pregnancy and delivers oxygen and nutrients to the growing foetus through its umbilical cord.

During the course of pregnancy, there is a natural expansion and displacement of the placenta: 

• In the beginning, it usually sits low inside the uterus. 
• As pregnancy advances into the third trimester, the placenta generally migrates to the top of the uterus, providing a clear passage for delivery. 
• When this process does not occur, the placenta obstructs the passage of the baby through the cervix during delivery, which is then called placenta previa.

What are the Different Types of Placenta Previa? 

Placenta previa can be classified into three main types based on how much of the cervix the placenta covers:

1. Marginal Placenta Previa 

Marginal previa, also known as low-lying placenta, occurs when the placenta is positioned close to the cervical opening but does not cover it. This type is more likely to resolve naturally before the baby’s due date as the uterus expands.

2. Partial Placenta Previa

Partial placenta previa occurs when the placenta covers a portion of the cervical opening.

3. Complete Placenta Previa

Complete or total placenta previa occurs when the placenta entirely covers the cervix, blocking the birth canal. This is the most severe form and is less likely to resolve on its own as the pregnancy progresses.

What are the Causes of Placenta Previa?

The following are the different causes of placenta previa:

• Placental Positioning

The position of the placenta within the uterus significantly impacts the risk of placenta previa. When the placenta attaches itself to the lower segment of the uterus, closer to the cervix, the chances of developing placenta previa rise.

• Uterine Shape

An abnormally shaped uterus, whether due to congenital conditions or the presence of fibroids, can contribute to placenta previa. Such irregularities may interfere with the placenta’s normal implantation, leading to complications.

• Uterine Scarring

Previous surgical procedures, including cesarean sections or dilation and curettage (D&C), can leave scar tissue within the uterine cavity. These scars may hinder the proper attachment of the placenta, increasing the risk of placenta previa.

What are the Risk Factors Associated with Placenta Previa?

Certain factors can increase the likelihood of developing placenta previa. Knowing these risk factors can help you in early detection and management:

• Age

Pregnant individuals aged 35 or older are at a higher risk of placenta previa.

• Multiple Pregnancies

Carrying twins, triplets, or more can affect where the placenta attaches inside the uterus.

• Previous Pregnancies (Multigravida)

Having been pregnant before may raise the chances of experiencing placenta previa.

• Assisted Reproduction

Conception through in vitro fertilisation (IVF) or other fertility treatments may increase the risk.

• Uterine Scarring

Previous surgeries on the uterus, such as a C-section, fibroid removal, or D&C after a miscarriage, can result in scarring that elevates the risk of placenta previa.

• Smoking

The harmful substances in cigarettes, like nicotine and carbon monoxide, can disrupt blood flow to the placenta, potentially affecting its placement and development.

• Substance Abuse

Use of drugs, particularly cocaine or crack, is linked to a higher risk of placenta previa.

What are the Symptoms of Placenta Previa?

Here are the key signs and symptoms of placenta previa that one must look out for:

• Sudden Vaginal Bleeding

Usually painless, this bleeding can vary in intensity from mild spotting to severe haemorrhage. It often occurs without warning during the second or third trimester.

• Abdominal Discomfort

Some individuals may experience mild to moderate pain or cramping in the lower abdomen.

• Uterine Contractions

In some cases, placenta previa can trigger contractions, which may resemble normal pregnancy pains.

• Fetal Distress

The baby may show signs of stress, such as an irregular heart rate or reduced movement.

How to Diagnose Placenta Previa? 

Diagnosing placenta previa primarily involves ultrasound imaging, which helps healthcare professionals assess the situation accurately:

• Placental Location and Coverage

The scan pinpoints where the placenta is situated within the uterus and determines if it partially or completely covers the cervix. This helps in identifying the type and severity of placenta previa.

• Fetal Health Assessment

Ultrasound also monitors the baby’s growth and development to ensure that the abnormal placental position is not impacting foetal nourishment or oxygen supply.

• Guiding Treatment Decisions

Based on the ultrasound findings, healthcare providers develop a customised treatment plan. The approach may vary depending on the severity and type of placenta previa diagnosed.

What are the Complications of Placenta Previa?

Placenta previa can lead to various complications that may impact both the mother and the baby. Here is what you need to know:

Complications for the Mother

• Heavy Bleeding: Severe bleeding can occur during pregnancy, labour, or delivery, posing a significant risk to maternal health.
• Preterm Delivery: If the bleeding is critical, healthcare providers may perform an emergency C-section before the baby reaches full term (40 weeks).
• Excessive Blood Loss: Significant blood loss may lead to anaemia, low blood pressure, pale skin, or shortness of breath.
• Placenta Accreta: In this condition, the placenta embeds too deeply into the uterine wall, causing substantial bleeding after delivery.
• Placental Abruption: This occurs when the placenta detaches from the uterine wall before childbirth, compromising the baby’s oxygen and nutrient supply.

Complications for the Baby

• Premature Birth: If an emergency C-section is needed due to severe maternal bleeding, the baby may be born prematurely.
• Low Birth Weight: Being born too early may result in a lower birth weight, potentially causing issues like difficulty maintaining body temperature or poor weight gain.
• Breathing Problems: If the baby’s lungs are underdeveloped at birth, respiratory issues may arise.

What are the Treatment Options for Placenta Previa?

Managing placenta previa involves taking into account various factors like the type and severity of the condition, the pregnancy stage, and the mother’s overall health. Here are some effective treatment approaches:

1. Bed Rest and Limited Activity

Reducing physical activity can help decrease pressure on the placenta and minimise the chances of bleeding. Depending on the severity of placenta previa, your healthcare provider might recommend complete bed rest at home or even hospitalisation to ensure safety.

2. Placenta Previa Medication to Prevent Preterm Labour

Since preterm labour is a common concern with placenta previa, healthcare providers may recommend placenta previa medication to delay labour and provide more time for the baby’s development. These medications can include:

• Tocolytics: These medicines help relax the uterine muscles to prevent contractions, reducing the risk of early labour associated with placenta previa.
• Corticosteroids: These are administered to promote lung development in the baby, preparing for the possibility of an early delivery.

3. Blood Transfusions

In cases of heavy bleeding, blood transfusions may be necessary to replace lost blood and stabilise the mother’s condition. This helps prevent complications like anaemia and shock caused by significant blood loss.

4. Hospitalisation for Continuous Monitoring

In severe placenta previa cases, hospitalisation might be essential for close monitoring. Medical professionals can provide immediate care if complications arise, ensuring both mother and baby remain safe.

FAQs About Placenta Previa 

1. Is it possible to have placenta previa without experiencing bleeding?

Placenta previa can occur without causing any bleeding. Mild or severe cramping or pelvic pain might still be present, warranting medical attention and regular monitoring for timely detection. It is essential not to disregard symptoms related to placenta previa.

2. Can placenta previa resolve on its own?

Placenta previa can sometimes resolve naturally as pregnancy advances, particularly when identified early. However, if diagnosed closer to the delivery date, it is less likely to resolve spontaneously.

3. Are there ways to lower the risk of placenta previa?

While some risk factors are beyond control, maintaining a healthy lifestyle, attending routine prenatal visits, and adhering to medical advice can support a healthier pregnancy.

4. Does placenta previa impact future fertility?

Experiencing placenta previa in one pregnancy does not necessarily affect fertility in subsequent pregnancies. Seeking guidance from healthcare professionals can provide more personalised insights.

5. Which activities should be avoided with placenta previa?

Engaging in activities that place excessive physical stress on the body, such as heavy lifting, strenuous aerobic exercises, or high-intensity workouts, should be avoided. Additionally, sexual intercourse is generally not recommended, as it may trigger bleeding in cases of placenta previa.

Conclusion

Placenta previa is a serious pregnancy complication that needs prompt medical attention to ensure the safety of both mother and baby. Staying informed about its symptoms and treatment options can help you make better decisions during pregnancy.

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