Placenta Previa and Low-Lying Placenta

What Is Placenta Previa?

The placenta is a special organ that develops in the uterus only during pregnancy. It provides nutrition and oxygen to the growing fetus and assists with the elimination of waste products via the umbilical cord connection. The baby is connected to the placenta through the umbilical cord. It is usually located near the top portion of the uterus. As pregnancy advances and the uterus stretches and grows, the placenta moves also.

The placenta is usually located low in the uterus during early pregnancy. But as the pregnancy progresses and by the third trimester, the placenta should be ideally near the top of the uterus. This allows the baby to be delivered through the cervix without anything blocking the path.

If there is placenta previa, it means the placenta is lying lower in the uterus, probably blocking the passage of the baby's arrival (cervix). This abnormal position of the placenta can result in severe bleeding throughout the pregnancy and delivery. Women with this condition must avoid strenuous activities, such as sex, douching, using tampons, running, and jumping. If the condition does not resolve, the baby might have to be delivered through a C-section.

What Are the Types of Placenta Previa?

A placenta previa can either cover the cervix partially or totally. So, depending on that, we have two types:

1. Partial placenta previa (minor) - Only part of the cervical opening is covered by the placenta.

2. Low-lying placenta previa - The placenta is positioned at the edge of the cervix and does not cover the opening.

3. Complete placenta previa (major) - The entire cervical opening is covered by the placenta.

4. Marginal placenta previa - In this case, the placenta lies in the lower segment of the uterus and presses the cervix. The edge of the placenta is within 2 cm of the cervix and not covering the opening.

What Are the Signs and Symptoms of Placenta Previa?

Bright red, painless vaginal bleeding in the second or third trimester is a sign to suspect placenta previa. The other symptoms include sharp cramps, abdominal pain, and bleeding after sex. In a majority of women detected with placenta previa during early pregnancy, the placenta migrates upwards (due to the growth of the uterus), and the condition resolves independently. The doctor may order a scan to recheck the location after a few weeks.

But, in those whom it is still detected at later stages or still persists in the third trimester, it is less likely to migrate upwards any longer. Then, the delivery will be required to be done via a cesarean section.

Whereas, in minor (partial) cases, vaginal delivery may be attempted if deemed suitable by the attending doctor. Irrespective of a major or minor one, some precautions are called for during this pregnancy.

When to Call the Doctor?

If you have painless, bright red bleeding or spotting during the course of your pregnancy, it is critical to be at the hospital at the earliest. In case of severe bleeding, it can be life-threatening, and you may require blood transfusions. Also, consult the doctor for any other specific restrictions that may be applicable to you.

What Causes Placenta Previa?

The possible causes include:

1. Uterine scarring during previous cesarean section delivery, D and C procedures, or any other surgery involving the uterus.

2. When the functional capacity of the placenta is lowered due to multiple gestations, smoking mother, or living in a high altitude, the placenta grows larger to compensate for lost functions, and this causes placenta previa.

Risk Factors:

The following factors increase the risk of having placenta previa:

1. Breech (baby’s buttock is positioned to be delivered first) or transverse positioned baby (baby lies horizontally across the womb).

2. The uterus is shaped abnormally.

3. Multiple pregnancy.

4. History of a miscarriage.

5. Advanced maternal age.

6. Smoking.

7. Other uterine surgeries, which include cesarean delivery and dilation and curettage (D&C).

8. Abnormally large placenta.

9. Substance abuse.

10. Previous history of placenta previa.

How Does a Doctor Diagnose Placenta Previa?

This condition is usually diagnosed during a routine ultrasound at 20 weeks. But it is nothing to worry about, as the placenta, in the majority of cases, is positioned lower during early pregnancy. As the weeks go by, the placenta generally corrects itself. Only around 10 % of cases will lead to major placenta previa (according to the Royal College of Obstetricians and Gynecologists).

If you notice painless bleeding during the second half of your pregnancy, consult a doctor, who will detect the position of the placenta using the following methods:

1. Transvaginal ultrasound - A transducer is placed inside the vagina, which provides images of the inside of the uterus and cervix. This diagnosis placenta previa most accurately.

2. MRI (magnetic resonance imaging) - This gives detailed images of the placenta’s location.

How is placenta previa treated?

Depending on how much bleeding is occurring, the baby’s health, the position of the baby and placenta, and how far along you are, the doctor will form a treatment plan. The doctor usually monitors the amount of bleeding before treating the condition.

No to Minimal Vaginal Bleeding:

• Bed rest as much as possible.

• Standing and sitting only when absolutely necessary.

• Abstinence from sex.

• Reduce stress.

• Avoid traveling and bumpy roads.

• No vaginal examination.

• No vigorous exercises or jumping.

If you still bleed, then consult your doctor as soon as possible.

Considerable Amount of Vaginal Bleeding:

• This requires hospitalization and bed rest.

• You might need blood transfusion if you have lost a lot of blood.

• Medicines will be prescribed for premature labor.

Severe Vaginal Bleeding:

If you have severe vaginal bleeding, then the doctor will schedule a C-section as early as possible. It is usually done after 36 weeks. In case the C-section has to be done earlier, then the doctor injects corticosteroid injections to help the baby’s lungs mature fast.

Uncontrollable Vaginal Bleeding:

An emergency cesarean delivery is done.

What Are the Complications of Placenta Previa?

• For mother: Bleeding during labor and after delivery.

• For baby: Growth restriction, premature birth, and death.

To know more about the possible complications and treatment options of placenta previa, consult an obstetrician and gynecologist online.

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