Disclaimer:
This article is anchored to RCOG Green-top Guideline No. 63: Antepartum Haemorrhage (2011), which remains the current UK guideline for placental abruption in the absence of a dedicated NICE guideline. There is no standalone RCOG guideline specific to placental abruption.
Background Information
Definition
Placental abruption is the premature separation of the placenta from the uterine wall prior to delivery of the baby.
It involves bleeding from the site of placental separation within the uterus.
Epidemiology
Placental abruption is one of the most important causes of antepartum haemorrhage (bleeding from or into the genital tract occurring from 24 weeks of pregnancy up until the birth of the baby).
Antepartum haemorrhage complicates 3-5% of pregnancies and is a leading cause of maternal and perinatal mortality worldwide.
Placental abruption risk:
- Baseline risk: 1.0%
- Recurrent is 4.4% (after 1), and 19-25% (after 2)
Aetiology
The aetiology of placental abruption is not fully understood, but involves impaired placentation, placental insufficiency, uteroplacental underperfusion, and rupture of maternal decidual arteries, causing dissection of the decidual-placental interface. [Ref]
Risk Factors
~70% of all placental abruption cases occur in completely low-risk pregnancies. The majority of cases happen as a sudden and unexpected obstetric emergency without any known pre-existing conditions.
Risk factors for placental abruption include:
| Category | Specific risk factors |
|---|---|
| Lifestyle and environmental factors |
|
| Obstetric and reproductive history |
|
| Maternal characteristics |
Medical condition:
|
| Current pregnancy complications |
|
Clinical Features
Placental abruption is a cause of antepartum haemorrhage – bleeding that occurs from 24 weeks onwards
Sudden onset of:
- Abdominal pain (continuous)
- Vaginal bleeding (may be ‘concealed’ / not be present – see below)
Other signs:
- Uterine sign
- ‘Woody
Clinical finding of increased uterine tone and firmness on palpation, where the uterus feels unusually hard, rigid, or board-like.
This is due to the accumulation of blood within the myometrium and behind the placenta, leading to uterine muscle tetany and distension.
‘ or tense uterus on palpation - Uterine tenderness
- ‘Woody
- Fetal compromise (on CTGCardiotocography – as it often causes fetal hypoxia)
- Massive haemorrhage may cause maternal shock (e.g. tachycardia, hypotension, syncope)
~18% of placental abruption cases are concealed, where the bleeding is trapped behind the placenta, causing no or minimal vaginal bleeding. [Ref]
This is clinically important as the severity of haemorrhage cannot be reliably determined by the volume of external bleeding alone (visible blood loss can be little, but internal bleeding is significant).
Placental abruption should be suspected in the presence of continuous abdominal pain, a tense or woody uterus, and clinical shock, even in the absence of vaginal bleeding.
Complications
| Maternal complications |
|
| Fetal complications |
|
Diagnosis
Placental abruption is primarily a clinical diagnosis.
The following tests are recommended in patients with antepartum haemorrhage, but NOT to diagnose the abruption itself.
Blood Tests
Standard:
- FBC
- Group and save
For massive haemorrhage, also perform a coagulation screen, U&E, LFT, and cross-match
Imaging
1st line: ultrasound
- Normal ultrasound does not exclude abruption because it has limited sensitivity (~24%) in identifying retroplacental haemorrhage
- The primary purpose is to confirm or exclude placenta praevia (which can also cause antepartum haemorrhage)
Fetal Monitoring
Perform continuous CTGCardiotocography
- Fetal well-being is important in guiding management
If the fetal heartbeat cannot be heard using external auscultation → ultrasound immediately to establish whether there is fetal heart pulsation and rule out fetal death
Management
Immediate Management
Immediate priority: resuscitation and stabilisation of the mother
The mother must be stabilised before any decision is made regarding the fetus or establishing the fetal condition.
Definitive Management
First, determine whether there is maternal or fetal compromise:
| Maternal compromise | Fetal compromise |
|---|---|
Characterised by:
|
Indicated by abnormal CTG, including:
|
Maternal and/or Fetal Compromise (ANY Gestation)
Immediate delivery (usually category 1 “crash” Caesarean section)
Maternal compromise is characterised by:
- Life-threatening bleeding
- Cardiovascular instability
- Signs of clinical shock
Fetal compromise is evidenced by abnormal CTG features, especially:
- Sustained fetal bradycardia (baseline heart rate <110 bpm)
- Prolonged decelerations (>3 minutes)
Stable Mother and Fetus
Where there is no maternal or fetal compromise, management is guided by gestational age.
| Gestation | Recommended management |
|---|---|
| Term (≥37 weeks) | Consider induction of labour |
| Pre-term (<37 weeks) | Conservative management is appropriate (given the mother and fetus are stable)
In cases of extremely pre-term (<26 weeks), the decision is complex and senior obstetric input should be sought. |
Intrauterine Fetal Death
Vaginal birth is the recommended mode of delivery – regardless of gestation