Placenta previa

Refers to the implantation of the placenta over the cervix.

Occurs in 1 in 20 pregnancies.

3 types: marginal, with extension to the edge of the cervix, partial, with a portion of the placenta covering the cervix and complete where the cervical os is completely covered.

Usually present with painless vaginal bleeding during the third trimester.

Bleeding occurs as the lower third of the uterus stretches and thins in the third trimester with tearing at the margins.

As the cervix effaces and shortens in preparation of delivery, it shears off the vascular placental attachments above it , resulting in hemorrhage.

More common in women who have had children, are less then 20 years old, are older or smoke.

More common with large placentas.

Previous C-section or induced abortions may be associated with increased risk.

Associated with higher risk of congenital abnormalities.

Associated with increased risk of intrauterine growth restriction.

Diagnosis made at the time of bleeding or at the time of ultrasound examination.

9 out of 10 cases found before 20 weeks gestation disappear as the placental position changes as the uterus grows.

Treatment is immediate C-section or expectant management with bedrest and frequent monitoring until the newborn can survive outside the uterus.

Pelvic and rectal examinations are not to be done in PP unless staff is ready for emergency C-section.

May result in-life-threatening hemorrhage.

Associated with increased risk of postpartum hemorrhage.

Increased risk of placenta accreta.

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