202406292215

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Tags: Obstetrics

Placental abruption

defined as the partial or complete detachment of the placenta before delivery of the fetus, with dissection and bleeding at the interface between the decidua, that is the modified mucosal lining of the uterine endometrium, and the placenta

revealed = w/ vaginal bleeding
concealed = w/ blood encapsulated btw uterine wall & placenta

The Sher classification

• Stage I - mild
  • involves the retrospective diagnosis of a small postpartum haematoma
• Stage II - intermediate
  • a/w hypertonic uterus and delivery of a live fetus
• Stage III - severe
  • intrauterine fetal death
  • without (IIIa) or with (IIIb) the presence of coagulopathy

Between 0.4 and 1% of pregnancies may be affected by placental abruption and 70% of cases occur in patients who are at low risk

Risk factors

• Medical & social Hx
  • amphetamine / cocaine use
  • chronic hypertension
  • thrombophilia
  • smoking
  • maternal age >=35 or <=20
• Obstetric Hx
  • uterine abnormalities
  • previous Caesarean delivery
  • uterine leiomyoma
  • Parity >=3
• ischaemic placental disease Hx
  • prev placental abruption
  • prev pre-eclampsia
  • prev intrauterine growth restriction
• current pregnancy
  • pre-clampsia / eclampsia
  • chorioamnionitis
  • 1st trimester bleeding
  • polyhydramnios
  • multiple gestation pregnancy
  • PROM
  • IUGR
  • oligohydramnios
• trauma

Pathophysiology

∵ rupture of maternal placental vessels in the decidua basalis
(Bleeding from fetal placental vessels is rare)

Ischaemic placental disease → chronic abruption → decidual necrosis → maternal venous haemorrhage

Venous haemorrhage

• low pressure
• commonly at the periphery of placenta in marginal placental abruption
• slower onset of clinical manifestations

Arterial haemorrhage

• High-pressure
• centrally located
• rapid onset
• severe clinical manifestations

Shearing of the inelastic placenta may occur from:

• trauma
• rapid uterine decompression
  • after the delivery of the first fetus in the context of multiple gestation pregnancy
  • secondary to sudden loss of amniotic fluid
    • after delivery in the setting of polyhydramnios

Acute vasospasm may be the precipitant in cocaine use, resulting in ischaemia followed by reflex vasodilation

Fetal compromise caused by ↓ oxygen & nutrient transfer across the placenta

placental abruption involving >45% of placental area → very poor neonatal outcomes. Fetal mortality increases from 0.6% in deliveries w/o placental abruption to 3–12% in deliveries with placental abruption

decidual hypoxia → release of decidual tissue factor (i.e. thromboplastin) + VEGF → ↑thrombin

Thrombin → uterine hypertonus & DIC

Presentation

depends on site & severity of placental abruption

Chronic placental abruption

• can be asymptomatic
• intermittent vaginal bleeding
• oligohydramnios
• poor fetal growth
  Small & concealed placental abruption can be asymptomatic

Acute placental abruption

• abdominal pain
• back pain
• uterine contractions
• vaginal bleeding
  Labour may progress rapidly with uterine hypertonus

severity of placental abruption

• NOT correlate well w/ extent of vaginal bleeding
• indicated by
  • severe abdominal pain
  • maternal hypotension
  • fetal heart rate abnormalities

Management

Dx

primarily based on clinical features
must be considered in any patient in the context of trauma or with abdominal pain, vaginal bleeding, or both

Placental abruption is the cause of 10% of preterm labour and is often diagnosed at delivery

DDx

• labour
• placenta praevia
• uterine rupture

Concealed abruption + maternal haemodynamic compensation → underdiagnosis & underestimation of blood loss

In major haemorrhage, fibrinogen concentration and VHA guide the correction of coagulopathy to a greater extent than the results of conventional clotting studies.

Ultrasound has high specificity of 96% but poor sensitivity of 24% ∵ isoechogenicity of concealed haemorrhage and placental tissue.

Kleihauer–Betke test

• identifies presence of fetal cells in the maternal circulation
• performed in all rhesus-negative patients who have an antepartum haemorrhage
• poor correlation w/ placental abruption

Mode & timing of delivery

Chronic placental abruption + reassuring maternal & fetal status can be managed expectantly w/ planned induction of labour or Caesarean delivery at ∼37 weeks of gestation

Viable fetuses:
severe compromise → emergent CS unless vaginal delivery is imminent
reassuring status → non-urgent vaginal or caesarean delivery.

fetal death → vaginal delivery recommended unless maternal status is compromised or vaginal delivery is contraindicated

Management of haemorrhage

The principles of major obstetric haemorrhage management include:

• replacing circulating volume + oxygen carrying capacity
• correcting coagulopathy
• preventing complications of blood transfusion

VHA

• ↓ blood loss and blood product use in obstetrics
• repeat Q30min if major haemorrhage

Fibrinogen

• Maternal fibrinogen concentration normally 4–6 g/L
  • higher than non-pregnant patients
    • normally 2–4 g/L
• ↓ more rapidly than platelets & other clotting factors in major obstetric haemorrhage
• may be inadequate despite normal PT & APTT
• Fibrinogen <2 g/L insufficient to sustain effective coagulation
  • → predictive of severe haemorrhage
  • ROTEM FIBTEM A5 <12mm
  • TEG CFF-MA <=16mm

Cryoprecipitate: fibrinogen concentration of 15 g/L

Fresh frozen plasma (FFP):

• fibrinogen concentration of 2 g/L
• may dilute the maternal fibrinogen concentration ∵ large volume transfusion

FFP and platelet transfusions, although often unnecessary, are more likely to be needed in placental abruption relative to other causes of obstetric haemorrhage

When guided by haemostatic testing, many patients who have an obstetric haemorrhage do not require FFP

TXA

• given at a dose of 1g over 10 min IV
  • as supportive treatment in haemorrhage of >1000 ml
• fibrinogen replacement more effective when given AFTER TXA
• 2nd dose TXA should be considered once 30min passed + ongoing haemorrhage

When blood loss is >1500 ml → a repeat dose of antibiotic must be given

Postnatal

monitor for

• haemorrhage
• coagulopathy
• sequelae of major transfusion

References

Placental Abruption