Placental Abruption

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Placental abruption is the premature separation of a normally located placental from the uterine wall that occurs before full-term delivery of a foetus.

Abruption may be:

  • Overt [revealed] -> where blood escapes and manifests as vaginal bleeding.
  • Covert [concealed] -> where blood cannot escape and no vaginal bleeding is present.
  • Partial -> where only part of the placenta has separated.
  • Complete -> where the entire placenta has separated.



Abruption complicates, on average, 0.3% to 1% of pregnancies.

The incidence of abruption has risen slightly in recent years.

  • This is perhaps the consequence of improved ascertainment.
    • In comparison to white women, the incidence has been seen to rise more in black women.

Finally, a link between maternal ages has been associated with a higher incidence of abruption. At greater risk are:

  • Women <20-years-old.
  • Women >35-years-old.


Aetiology [Risk Factors]

Maternal chronic hypertension [high blood pressure] and pre-eclampsia [acute onset of high blood pressure and proteinuria from renal injury, associated with pregnancy; diagnosed by SBP >140 mmHg or DBP >90 mmHg on ≥2 occasions].

  • Chronic HTN and/or pre-eclampsia is the most common documented cause/risk factor, having been reported in 44% of abruption cases (Deering, 2018).

Cocaine use.

  • Cocaine-induced hypertension and catecholamine elevation are thought to be responsible for vasospasm in uterine blood vessels which causes placental separation and abruption (Deering, 2018).
  • Cocaine is thought to indicate a 13% to 35% risk-increase, but this may be dose-dependent.

Maternal abdominal trauma [i.e. RTC, domestic violence].

  • Reported in 1.5% to 9.4% of cases (Deering, 2018).
  • Shearing forces associated with rapid acceleration/deceleration may result in placental separation.
    • Often, the lower seatbelt in a motor vehicle crosses the lower abdomen of the mother, rather than the pelvic area, exacerbating abdominal trauma.
  • Cases of domestic violence and assault are thought to go underreported.

Tobacco Smoking.

  • Consistently documented to be a significant risk.
  • One study found those who smoke tobacco were at a 2-fold risk increase of abruption, while another study reported that, for every year of smoking prior to conception, the risk of abruption increased by 40% (Deering, 2018).
  • Infants born to mothers who smoke and have an abruption have a further elevated risk of mortality due to maternal smoking.

Other WEAK risk factors include:

  • Multiparity.
  • Prior caesarean section delivery.
  • Advanced[ing] maternal age.
    • Abruption is more common in those >35-years old.
    • Conversely, mothers <20-years-old are also at an elevated risk of abruption.
  • Thrombophilia disease.


Diagnostic Features

Vaginal bleeding -> present in 80% of cases.

  • In abruption, this is usually painful.
    • This knowledge helps a clinician to differentiate between abruption and praevia [where vaginal bleeding is often painless].
  • In covert abruptions, vaginal bleeding is concealed.

Abdominal or back pain -> present in 70% of cases.

Foetal distress -> present in 60% of cases.

Abnormal uterine contractions -> 35% of cases.

  • Uterine activity is a sensitive marker of abruption.
  • In the absence of vaginal bleeding, uterine activity should suggest the possibility of an abruption, especially after trauma, or in a patient with multiple risk factors.

Premature labour -> 25% of cases.

Foetal death -> 15% of cases.



Universal precautions.

  • PPE.
  • Scene safety.

Global overview.

<C>ABCDE approach


  • PV bleeding.
  • Trauma.
    • Mechanism.
  • Chronic HTN or pre-eclampsia.
  • Smoker.
  • Cocaine use.
  • Prior praevia or abruption.

Signs and symptoms.

  • PV bleeding.
  • Abdominal pain.
  • Monitoring.
    • Hypotension and tachycardia = red flags -> signs of inadequate organ perfusion [also tachypnoea and decreased consciousness].
  • Contractions.


  • Rigidity.
  • Guarding.
  • Rebound tenderness.
  • Organomegaly.
  • Bruising.
  • Foetal heart.



<C>ABCDE approach.

Stabilisation and monitoring of mother and foetus.

TIME-CRITICAL transfer and pre-alert.

Wide-bore, bilateral IV access.


  • Blood pressure.
  • Heart rate.
  • Respiratory rate.
  • Volume intake.
  • Urinary output.
  • SpO2.
  • Temperature.
  • Blood sugars.



Intravascular fluid therapy.

  • Little evidence exists to support the administration of fluids in adult acute blood loss (AACE and JRCALC, 2016).
    • The administration should occur only in the presence of major organ perfusion impairment (AACE and JRCALC, 2016).
  • Administer en-route. DO NOT delay on scene to achieve venous access in a time-critical emergency (AACE and JRCALC, 2016).
  • Dosage and administration:
    • Initial – 250 millilitres.
    • Repeat – 250 millilitres.
    • Interval – N/A.
    • Concentration – N/A.
    • Volume – N/A.
    • Max dose – 2 litres.

Tranexamic acid.

  • Indications: patients with TIME CRITICAL injury where significant internal or external haemorrhage is suspected.
  • Mechanism of action: an antifibrinolytic that competitively inhibits the activation of plasminogen to plasmin.
  • Contraindications:
    • isolated head injury;
    • critical intervention required;
    • bleeding now stopped.
  • Side effects: rapid injection may, rarely, cause hypotension.
  • Benefits obtained if given within 3 hours of injury.
  • Safe and effective, a 9% mortality reduction observed in the CRASH-2 trial.
    • No evidence exists the suggest TXA is harmful in head injuries.High-dose regimens have been associated with convulsions, but the low doses recommended by JRCALC outweigh the risks of convulsing.
  • Maybe given IV [or IO, depending on local policy – IO use is unlicensed].
  • Dosage and administration:
    • Initial – 1 gram.
    • Repeat – none.
    • Interval – N/A.
    • Concentration – 100 mg/mL.
    • Volume – 10 mL.
    • Max dose – 1 gram.

Differential Diagnoses [∆∆]

  • Preterm labour.
    • May co-exist with abruption.
    • Bleeding is typically light, rather than moderate to heavy.
  • Placenta praevia.
    • Painless vaginal bleeding.
      • ± painful contractions.
  • Appendicitis.
    • No vaginal bleeding.
    • Pain typically located RLQ or peri-umbilical.
    • Often associated with:
      • vomiting;
      • fever;
      • anorexia.
  • Pyelonephritis.
    • No vaginal bleeding.
    • Frequently associated with:
      • dysuria;
      • fever;
      • rigours;
      • flank pain;
      • costovertebral angle tenderness.
  • UTI.
    • No vaginal bleeding.
    • Frequently associated with:
      • dysuria;
      • suprapubic pain.

Complications and Prognosis


  • Hypovolaemic shock.
    • Blood loss may be concealed, resulting in a greater haemorrhage than is recognised.
  • Disseminated intravascular coagulation.
  • Surgical and anaesthetic risks.
  • Foetal neurological impairment.
  • Acute renal failure.
    • Acute tubular necrosis caused by hypovolaemic shock.
    • Acute cortical necrosis caused by the breakdown of blood products.
      • May ultimately result in chronic renal failure.



  • Depends on gestational age.
  • High risks of perinatal death, associated with extremely preterm gestations and placental separations >50%.
  • Preterm birth associated with perinatal asphyxia and long-term neurodevelopment handicap.
  • The perinatal outcome may be good in cases where abruption is recognised early and delivery of the foetus is expeditious.


  • Linked with the severity of abruption, particularly the amount of blood lost and the presence or absence of associated coagulopathy.
  • Outcomes can be excellent if there is neither massive blood loss nor coagulopathy.
  • The risk of future abruptions rises following the first abruption.
  • Ischaemic placental disease.


Bibliography and References

Association of Ambulance Chief Executives (Great Britain) and Joint Royal Colleges Ambulance Liaison Committee (Great Britain) (2016) UK Ambulance Services Clinical Practice Guidelines 2016 Reference Edition. Edited by S. N. Brown, D. Kumar, M. Millins, and J. Mark. Bridgwater: Class Professional Publishing.

Deering, S.H. (2018) Abruptio Placentae. Available at: (Accessed: 24 December 2018).

Oyelese, Y. and Ananth, C.V. (2006) ‘Placental abruption’, Obstetrics and Gynaecology, 108(4), pp. 1005-1016. doi: 10.1097/01.AOG.0000239439.04364.9a.

Oyelese, Y. and Vintzileos, A.M. (2018) Placental abruption. London: BMJ.


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