Placental abruption is the separation of the placenta from the uterine wall during pregnancy (prior to delivery. It is a serious complication in pregancy that occurs in 1/200 pregnancies. It is associated with both perinatal morbidity and mortality
⚠️ Pathophysiology and risk factors
The aetiology of placental abruption is not well understood. What occurs is the maternal vessels within the endometrium rupture and this causes blood to accumulate between the placenta and its attachment to the endometrium. This splits the attachment and compromises that portion of the placenta which can cause foetal distress.
However it is associated with the following:
- Hypertension/hypertension
- Cocaine use
- Smoking
- Trauma
- Multiparity
- Advanced maternal age
- History of placental abruption
- Structural uterine abnormalities
- Chorioamnionitis
- Thrombophilias
🔢 Classification
We can classify placental abruption based on whether or not vaginal bleeding is seen or not. We can label it as either
- Revealed abruption - the blood will make its way down to the cervix and pass through into the vagina.
- Concealed abruption - the blood accumulates behind the detached portion of the placenta but does not track down to the cervix and vaginal bleeding is not seen. Often a clot forms behind the placenta, however, enough bleeding may occur to lead to systemic compromise and shock.
😷 Presentation
Placental abruption is different to placenta praevia by presenting with vaginal bleeding (antepartum haemorrhage) that is associated with abdominal pain and a hard uterus.
- Abdominal pain - the pain may be sudden, continuous and severe in nature.
- Lower back pain - sometimes presents with just lower back pain in cases of concealed abruption.
- Hard, tender uterus on palpation. It is often referred to as “woody” as it has the similar feeling to wood.
- Uterine contractions - low-amplitude contractions occurring more frequently. Thrombin (a procoagulant) induces uterine contractions also which is why a lot of women with placental abruption are in labour.
- Shock - the shock may not be proportional to the losses that are visible as a lot of the blood may be concealed still.
- Reduced foetal movements
- Absent foetal heart rate/foetal distress
We can classify antepartum haemorrhage on the amount of blood losses incurred, based on the RCOG guidelines:
- Spotting - blood spots noticed on underwear.
- Minor haemorrhage - <50ml of blood lost.
- Major haemorrhage - 50-1000ml of blood lost.
- Massive haemorrhage - >1000ml of blood lost.
🔍 Investigations
⭐️ Placental abruption is a clinical diagnosis based on presentation and clinical examination. There is no reliable test to diagnose abruption, however, we may wish to perform certain investigations if uncertain
- Cardiotocography - we need to monitor the foetal heart rate continuously to assess for any foetal distress. Foetal bradycardia (<110bpm) is of concern.
- Ultrasound - ultrasound unfortunately is not so useful when detecting placental abruption with detecting rates of only 25% approximately. What we may find is a retroplacental haemorrhage. If it is found, the positive predictive value of USS is good but we cannot rule it out with a negative USS (poor negative predictive value).
- Kleihauer-Betke test - this is used to assess the Rhesus status in the woman. If the woman is rhesus negative → give anti-D.
- Coagulation studies - looking for DIC (thrombocytopenia, low fibrinogen, prolonged prothrombin time, elevated D-dimmer).
- FBC - looking for anaemia.
🧰 Management
Our management depends on the condition of the mother as well as the foetus. If the mother has haemodynamic instability or the foetus is in distress then it is important to manage the condition urgently
Our first aim with management is stabilisation of the mother and monitoring of mother and baby. This can be done with an A-E approach.
We can divide the management based on if the foetus is alive or if the foetus is dead:
- Live foetus
- >36 weeks
- Reassuring foetal/maternal status → vaginal delivery.
- Foetal distress/maternal compromise → urgent C-section.
- <36 weeks
- Reassuring foetal/maternal status → delay labour. We need to just observe the mother and baby and give:
- Tocolysis - nifedipine for example.
- Corticosteroid - such as betamethasone. Given for lung maturation between weeks 24-34.
- Foetal distress/maternal compromise - urgent C-section.
The management for a live foetus is then subdivided based on the gestational period being >37+0 weeks or <37 weeks.
Delivery should be aimed for between week 37-38.
- Dead foetus
If the foetus is dead and the mother is stable then we should deliver the dead foetus via vaginal delivery. If the mother is also compromised then an urgent C-section can also be performed.
- Anti-D should be given within 72 hours of all cases of antepartum haemorrhage if the mother is rhesus negative.
- Third stage of labour (delivery of placenta) should have active management as they are anticipated to have postpartum haemorrhage. This includes giving uterotonics, early cord clamping and controlled cord traction.
- Synotcinon - a synthetic oxytocin that is used to induce labour but also is used to prevent postpartum haemorrhage by contracting the uterus to clamp the uterine arteries.
An A-E approach needs to be adopted for stabilisation of the mother. A senior obstetrician and anaesthetist need to be contacted.
We need to do certain interventions and investigations:
- Insert 2 grey (16g) bore cannulae
- Crossmatch 4 units of blood and give IV fluids
- FBC, U&Es, LFTs, coagulation studies - to assess for anaemia, proteinuric hypertension, HELPP syndrome and DIC.
- CTG monitoring of baby
🚨 Complications
Maternal complications
- Hypovolaemic shock
- DIC
- Postpartum haemorrhage
- Acute kidney injury
Foetal complications
- IUGR
- Preterm birth
- Intrauterine/perinatal death
- Foetal hypoxia