Antepartum Hemorrhage

Antepartum haemorrhage is bleeding from the genital tract in later pregnancy, before delivery, and is a major obstetric emergency because the uteroplacental circulation can produce rapid, large blood loss that threatens both mother and fetus. Its principal placental causes, placenta praevia and placental abruption, are considered alongside the broader problem of obstetric haemorrhage, which is a leading cause of maternal death worldwide.

Definition

Antepartum haemorrhage is bleeding from or into the genital tract occurring from the threshold of fetal viability until delivery; its major identifiable causes are placenta praevia (a placenta overlying or near the cervix) and placental abruption (premature separation of a normally sited placenta).

Scope

This entry covers the definition of antepartum haemorrhage, its main placental causes and their mechanisms, the link to abnormally invasive placentation and prior caesarean delivery, and the place of obstetric haemorrhage in global maternal mortality. It treats the topic as a clinical entity for reference and does not provide dosing or individualised management. Bleeding after delivery is addressed under postpartum haemorrhage.

Core questions

• What distinguishes the major causes of antepartum haemorrhage, particularly placenta praevia from placental abruption?
• How does the placental site or its premature separation produce dangerous bleeding?
• How does prior caesarean delivery contribute to placenta praevia and to abnormally invasive placentation?
• Why is obstetric haemorrhage such a prominent cause of maternal death globally?

Key concepts

• Placenta praevia
• Placental abruption
• Placenta accreta spectrum
• Uteroplacental blood flow
• Concealed versus revealed bleeding
• Prior caesarean delivery as a risk factor
• Obstetric haemorrhage and maternal mortality

Mechanisms

Late-pregnancy bleeding from the placental site is dangerous because the term uteroplacental circulation carries a large fraction of maternal cardiac output. In placenta praevia, the placenta implants over or near the cervix, so cervical change and lower-segment stretching shear placental vessels and cause bleeding that is typically painless and revealed. In placental abruption, the placenta separates prematurely from the uterine wall and blood collects behind it; bleeding may be revealed or concealed, and the separation compromises fetal oxygenation and can trigger coagulopathy. A scarred uterus from prior caesarean delivery predisposes both to praevia and to the placenta accreta spectrum, in which the placenta invades abnormally and is associated with severe haemorrhage at delivery (Jauniaux and Jurkovic, 2012; Silver and colleagues, 2006).

Clinical relevance

Antepartum haemorrhage is an obstetric emergency that can rapidly become life-threatening for mother and fetus, and obstetric haemorrhage overall is among the leading causes of maternal death. This entry describes the causes, mechanisms, and risk factors as a reference framework; it is not a source of dosing or individualised treatment recommendations.

Epidemiology

Haemorrhage is the single largest direct cause of maternal death worldwide, with the greatest burden in lower-resource settings (Say and colleagues, 2014). Systematic review confirms that haemorrhage, including its antepartum and postpartum forms, is a common and serious obstetric complication, and the rising frequency of caesarean delivery has increased the incidence of placenta praevia and the placenta accreta spectrum (Carroli and colleagues, 2008; Silver and colleagues, 2006; Jauniaux and Jurkovic, 2012).

Evidence & guidelines

Obstetric haemorrhage is addressed by professional guidelines and by systematic reviews of its epidemiology and causes; the cited guidance and reviews summarise the causes and burden, while the placenta accreta spectrum is increasingly recognised as an iatrogenic consequence of repeat caesarean delivery (American College of Obstetricians and Gynecologists, 2017; Carroli and colleagues, 2008; Jauniaux and Jurkovic, 2012).

History

The principal causes of late-pregnancy bleeding were clinically distinguished long before imaging, but obstetric ultrasound transformed the antenatal diagnosis and localisation of placenta praevia. The marked rise in caesarean delivery over recent decades has reshaped the epidemiology, making the placenta accreta spectrum a prominent, largely iatrogenic cause of severe obstetric haemorrhage.

Seminal works

• say-2014
• carroli-2008
• jauniaux-2012

Frequently asked questions

What is the difference between placenta praevia and placental abruption?

Placenta praevia is a placenta lying over or near the cervix, which characteristically causes painless revealed bleeding, whereas placental abruption is premature separation of a normally sited placenta, which often causes pain and may produce concealed bleeding behind the placenta.

Why does a previous caesarean delivery matter for later bleeding?

A uterine scar predisposes to placenta praevia and to the placenta accreta spectrum, in which the placenta implants abnormally into the scar; both are associated with a higher risk of severe haemorrhage at delivery.