Placental abruption refers to when the placenta separates from the wall of the uterus during pregnancy. The site of attachment can bleed extensively after the placenta separates. Placental abruption is a significant cause of antepartum haemorrhage.
The risk factors for placental abruption are:
- Previous placental abruption
- Bleeding early in pregnancy
- Trauma (consider domestic violence)
- Multiple pregnancy
- Fetal growth restriction
- Increased maternal age
- Cocaine or amphetamine use
The typical presentation of placental abruption is with:
- Sudden onset severe abdominal pain that is continuous
- Vaginal bleeding (antepartum haemorrhage)
- Shock (hypotension and tachycardia)
- Abnormalities on the CTG indicating fetal distress
- Characteristic “woody” abdomen on palpation, suggesting a large haemorrhage
Severity of Antepartum Haemorrhage
The RCOG guideline (2011) defines the severity of antepartum haemorrhage as:
- Spotting: spots of blood noticed on underwear
- Minor haemorrhage: less than 50ml blood loss
- Major haemorrhage: 50 – 1000ml blood loss
- Massive haemorrhage: more than 1000 ml blood loss, or signs of shock
Concealed abruption is where the cervical os remains closed, and any bleeding that occurs remains within the uterine cavity. The severity of bleeding can be significantly underestimated with concealed haemorrhage.
Concealed abruption is opposed to revealed abruption, where the blood loss is observed via the vagina.
There are no reliable tests for diagnosing placental abruption. It is a clinical diagnosis based on the presentation.
Placental abruption is an obstetric emergency. The urgency depends on the amount of placental separation, extent of bleeding, haemodynamic stability of the mother and condition of the fetus. It is important to consider concealed haemorrhage, where the vaginal bleeding may be disproportionate to the uterine bleeding.
The initial steps with major or massive haemorrhage are:
- Urgent involvement of a senior obstetrician, midwife and anaesthetist
- 2 x grey cannula
- Bloods include FBC, UE, LFT and coagulation studies
- Crossmatch 4 units of blood
- Fluid and blood resuscitation as required
- CTG monitoring of the fetus
- Close monitoring of the mother
Ultrasound can be useful in excluding placenta praevia as a cause for antepartum haemorrhage, but is not very good at diagnosing or assessing abruption.
Antenatal steroids are offered between 24 and 34 + 6 weeks gestation to mature the fetal lungs in anticipation of preterm delivery.
Rhesus-D negative women require anti-D prophylaxis when bleeding occurs. A Kleihauer test is used to quantify how much fetal blood is mixed with the maternal blood, to determine the dose of anti-D that is required.
Emergency caesarean section may be required where the mother is unstable, or there is fetal distress.
There is an increased risk of postpartum haemorrhage after delivery in women with placental abruption. Active management of the third stage is recommended.
Last updated September 2020