Placenta Previa
Low Lying Placenta: May Cause Severe Vaginal Bleeding

Pregnancy Complications

difference between normal and low lying placenta

Placenta Previa


What Is Placenta Previa?
Types Of Placenta Previa
What Are The Signs?
How Is It Diagnosed?
How Is It Treated?
Do I Need To Have A Cesarean Section?
What Complications Can It Cause?
What Is Vasa Previa?

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What Is Placenta Previa?

The placenta is the pan-caked shaped organ that supplies blood and oxygen to your growing baby through the umbilical cord. It is normally located near the top of the uterus (womb). If you have placenta previa it means that the placenta is positioned lower than usual and is close to the cervix. If the placenta is found low in early pregnancy it usually does not cause a problem. As the pregnancy progresses the placenta is likely to 'migrate' further away from the cervix. If it is close to the cervix later in pregnancy it can cause bleeding (hemorrhaging) and other complications. You may need to deliver early by cesarean section. Placenta previa is not very common, it occurs in about 1 in every 200 pregnancies. There are several factors which increase your risk:

Age: Experiencing a pregnancy after 35.
Parity: The number of previous children you had - the more children, the higher the risk.
Twins: Women pregnant with twins.
Scarring: Uterus is scarred from previous surgery, pregnancy, abortion procedure or c-section.
Previous episodes: If placenta previa has occurred in one pregnancy it is quite likely to recur in others.
Placenta problems: Placental insufficiency or an abnormal shaped placenta.

Types Of Placenta Previa

There are different types of placenta previa:

picture of low lying placenta

1. Marginal and Low-Lying
Placenta is next to the cervix but does not cover the opening. A marginal placenta is closer to the cervix than a low-lying one.
2. Partial
Placenta covers part of the cervical opening.
3. Complete
Placenta covers all of the cervical opening.

The degree of placenta previa depends not only on the placenta location, but also by how much the cervix is dilated. A marginal placenta previa at 2cm cervix dilation can become partial previa when the cervix is 8 cm dilated - simply because the wider opening of the cervix, the closer it comes to the edge of the placenta.

What Are The Signs?

The main sign is sudden painless bleeding from the vagina. Bleeding:
• Is bright red.
• Often starts near the end of the second trimester or beginning of the third trimester.
• The initial bleeding is usually very heavy (although it can be light) and stops by itself. It can then start again a few days or weeks later.
• Bleeding may start without cause (perhaps while sleeping) or after a physical disturbance, like intercourse.
• Labor usually starts after a few days of severe bleeding.
• Sometimes there may be no bleeding until labor starts.
• Fetal heartbeat and movements are normal. Any blood loss is maternal, not fetal.

How Is It Diagnosed?

Whenever there is bleeding in late pregnancy, placenta previa or placenta abruption is suspected. An ultrasound scan can diagnose either condition. A manual pelvic examination should never be performed because it could prompt a life-threatening hemorrhage. In most instances placenta previa is diagnosed during a routine mid-pregnancy ultrasound (anatomy scan, week 18-22). There may be no symptoms this early. If you are diagnosed, try not to panic. In most instances as the pregnancy progresses the placenta migrates back up the womb and the problem is resolved. You will receive a third trimester ultrasound as a follow up to check the location. If you have any bleeding in the meantime, an ultrasound will be performed to see what is going on. Only a small percentage of women with low lying placentas at week 20 still have them by the time they deliver their baby. With complete placenta previa, the position is not likely to improve.

How Is It Treated?

In the situation where there is uncontrolled bleeding, an emergency cesarean section is performed. But more commonly, the woman is admitted to hospital when bleeding has only been slight and there is still time to check the position of the placenta by ultrasound. At this point the doctor will carefully weigh up the risks of further bleeding against delivery of the baby. After 36 weeks delivery may be the best treatment. Before this, you will be recommended:

• Bed rest
• Pelvic rest, which means no tampons, douching or sexual intercourse. Nothing should be inserted into the vagina.

Your doctor may admit you to hospital so that your pregnancy healthcare team can monitor the situation closely. You may need blood transfusions, drugs to prevent early labor, and steroids to help the baby's lungs mature faster. You may also be given a shot of Rhogam, a special medicine if your blood type is Rh-negative. If despite all this treatment, severe bleeding starts, an emergency c-section will need to be performed. If however you do well, a c-section will be scheduled for about week 37. You may even be sent home in the meantime but told to return immediately if bleeding starts again.

Do I Need To Have A Cesarean Section?

Women with total placenta previa, or with any kind of placenta previa accompanied by heavy bleeding must be delivered by c-section. This is because delivery is faster by c-section and results in less blood loss. However, women with marginal or low lying placenta previa who have had children before, and are well into labor (cervix dilated at least 4cm) may have a simple vaginal delivery. For this to happen the bleeding should not be severe, there should be no sign of fetal distress and the delivery needs to be imminent. These conditions apply to about 50 percent of all cases.

What Complications Can It Cause?

The major danger of placenta previa to the baby is premature delivery before major organs such as the heart and lungs have had time to fully mature. As a result, hospitalization in a center with neonatologist or perinatologist specialized care will ensure the best care for your baby if he is born early. Placenta previa has also been linked to intrauterine growth restriction (IUGR). The biggest risk to the mother is severe bleeding and blood loss.

What Is Vasa Previa?

vasa previa

Vasa previa is a rare cause of antepartum bleeding and occurs when one or more of the baby's placenta or umbilical cord vessels crosses the entrance to the birth canal under the baby. When the cervix dilates or the membranes rupture for birth, the vessels can tear causing rapid fetal blood loss. Blood loss associated with placenta previa comes from the mother but with Vasa previa, the blood loss is from the baby. The baby is starved of oxygen and the mortality rate (if not diagnosed early enough) is 95 percent. Vasa previa can be seen in a routine anatomy scan.

  Related Articles on Pregnancy Problems

For more potential problems, see the following:

Bleeding during pregnancy: List of possible causes.
Postpartum bleeding: Causes and treatment.
Premature rupture of membranes (PROM): Signs and treatment

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