About placenta previa

What is placenta previa?

Placenta previa is the attachment of the placenta to the wall of the uterus in a location that completely or partially covers the uterine outlet (opening of the cervix).

  • Bleeding after the 20th week of gestation is the main symptom of placenta previa.
  • An ultrasound examination is used to establish the diagnosis of placenta previa.
  • Treatment of placenta previa involves bed rest and limitation of activity. Tocolytic medications, intravenous fluids, and blood transfusions may be required depending upon the severity of the condition.
  • A Cesarean delivery is required for complete placenta previa.
  • Other complications of pregnancy can be associated with placenta previa, but the majority of women deliver healthy babies.

What is placenta previa?

Placenta previa is the most common cause of painless bleeding in the later stages of pregnancy (after the 20th week). The placenta is a temporary organ that joins the mother and fetus and transfers oxygen and nutrients from the mother to the fetus. The placenta is disk-shaped and at full term measures about seven inches in diameter. The placenta attaches to the wall of the uterus (womb). Placenta previa is a complication that results from the placenta implanting either near to, or overlying, the outlet of the uterus (the opening of the uterus, the cervix).

Because the placenta is rich in blood vessels, if it is implanted near the outlet of the uterus, bleeding can occur when the cervix dilates or stretches.

What are the types of placenta previa?

The types of placenta previa include:

  • Complete placenta previa occurs when the placenta completely covers the opening from the womb to the cervix.
  • Partial placenta previa occurs when the placenta partially covers the cervical opening
  • Marginal placenta previa occurs when the placenta is located adjacent to, but not covering, the cervical opening.

The term low-lying placenta or low placenta has been used to refer both to placenta previa and marginal placenta previa. Sometimes, the terms anterior placenta previa and posterior placenta previa are used to further define the exact position of the placenta within the uterus as defined by ultrasound examinations.



What are the symptoms for placenta previa?

Contractions symptom was found in the placenta previa condition

Bright red Vaginal bleeding without pain during the second half of pregnancy is the main sign of placenta previa. Some women also have contractions.

In many women diagnosed with placenta previa early in their pregnancies, the placenta previa resolves. As the uterus grows, it might increase the distance between the cervix and the placenta. The more the placenta covers the cervix and the later in the pregnancy that it remains over the cervix, the less likely it is to resolve.

When to see a doctor

If you have Vaginal bleeding during your second or third trimester, call your doctor right away. If the bleeding is severe, seek emergency medical care.



What are the causes for placenta previa?

The exact cause of placenta previa is unknown.



What are the treatments for placenta previa?

Treatment of placenta previa depends upon the extent and severity of bleeding, the gestational age and condition of the fetus, the position of the placenta and fetus, and whether the bleeding has stopped.

Cesarean delivery (C-section) is required for complete placenta previa and may be necessary for other types of placenta previa. A Cesarean delivery is usually planned for women with placenta previa as soon as the baby can be safely delivered (typically after 36 weeks' gestation), although an emergency Cesarean delivery at any earlier gestational age may be necessary for heavy bleeding that cannot be stopped after treatment in the hospital (see below).

Women who are actively bleeding or who have bleeding that cannot be stopped will be admitted to the hospital for further care. If there has been little or no bleeding or the bleeding has stopped, bed rest at home may be prescribed. Home care is not always appropriate, and women who remain at home must be able to access medical care immediately should bleeding resume. Women with placenta previa in the 3rd trimester of pregnancy are advised to avoid sexual intercourse and exercise and to reduce their activity level.

Women with placenta previa who experience heavy bleeding may require blood transfusions and intravenous fluids. In some cases, tocolytic drugs (medications that slow down or inhibit labor), such as magnesium sulfate orterbutaline (Brethine) are necessary. Corticosteroids may be given to enhance lung development in the fetus prior to Cesarean delivery.

 



What are the risk factors for placenta previa?

Placenta previa is more common among women who:

  • Have had a baby
  • Have scars on the uterus, such as from previous surgery, including cesarean deliveries, uterine fibroid removal, and dilation and curettage
  • Had placenta previa with a previous pregnancy
  • Are carrying more than one fetus
  • Are age 35 or older
  • Are of a race other than white
  • Smoke
  • Use cocaine



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