Placenta praevia

Learning objectives

When the placenta attaches inside the uterus near or over the cervical opening
Classified as a complication of pregnancy
Commonly occurs around 32 weeks of gestation, however, placenta praevia should be suspected if there is bleeding after 24 weeks of gestation
Affects approximately 0.5% of pregnancies
A caesarean section is often required because of the high bleeding risk
The cause is unknown, however, is thought to be related to abnormal vascularisation of the endometrium caused by scarring or atrophy from previous trauma, surgery, or infection

Minor
- Placenta is in the lower uterine segment, but the lower edge does not cover the internal os
Major
- Placenta is in the lower uterine segment, and the lower edge covers the internal os
Other than that placenta previa can also be classified as:
- Complete:
  - The placenta completely covers the cervix, blocking the vagina
- Partial:
  - The placenta partially covers the cervix
- Marginal:
  - Placenta is positioned at the edge of the cervix
  - Touching but not covering the cervix
  - More likely to resolve on its own

Maternal	Fetal
Placenta accreta Hypotension Antepartum bleeding Placental abruption Postpartum hemorrhage Abnormal placentation	Intrauterine growth restriction Hypoxia Premature infant Low birth weight

Previous placenta previa, caesarean delivery, myomectomy, or endometrium damage caused by dilation and curettage
Younger than 20 or older than 35
Multiparity
Smoking or cocaine use during pregnancy
Pregnant with twins, triplets, or more
Previous surgery on the uterus
History of uterine fibroids