What Is Placenta Previa?
Placenta previa occurs when the placenta partially or completely covers the internal cervical os (the opening of the cervix). This can cause painless vaginal bleeding, particularly in the second and third trimesters, and significantly affects delivery planning — as vaginal birth is generally not safe with complete placenta previa.
Types of Placenta Previa
- Complete previa — the placenta completely covers the cervical os; caesarean delivery is required
- Partial previa — partial coverage of the os
- Marginal previa — the placental edge is at or near but not covering the os
- Low-lying placenta — placenta within 2cm of the os; often resolves by 32–36 weeks as the uterus grows
Management of Placenta Previa
- Serial ultrasound monitoring to assess placental migration as pregnancy progresses
- Activity restriction and avoidance of intercourse
- Hospitalisation for significant or recurrent bleeding
- Blood transfusion preparation for delivery
- Planned caesarean delivery — typically at 36–37 weeks for complete previa
- Multidisciplinary coordination with anaesthesia and neonatology teams
Placental Abruption
Placental abruption — premature separation of the placenta from the uterine wall — is a different but equally serious complication. It typically presents with painful vaginal bleeding and requires immediate evaluation. Management depends on severity, gestational age, and fetal condition.
Antepartum Haemorrhage — When to Seek Emergency Care
Any vaginal bleeding in pregnancy after 20 weeks should be evaluated promptly. Do not wait to see if it settles. Call your doctor or go to the nearest maternity emergency immediately.