Trauma during pregnancy

Learning objectives.

By reading this article, you should be able to:

• •Outline the complex management challenges that traumatic injury during pregnancy presents.
• •Describe expected variations in the pattern of injury and appropriate modification of trauma care principles after trauma in the pregnant patient.
• •Discuss the potential for obstetric complications after trauma and their subsequent assessment and management.

Key points.

• •Trauma is a leading cause of maternal mortality and presents unique challenges that require urgent multidisciplinary input to optimise outcomes.
• •Initial management must be focused on maternal assessment, resuscitation and stabilisation, and requires significant modification of contemporary trauma care principles.
• •Establishing maternal stability may not be possible without obstetric intervention and emptying of the uterus.
• •Concerns regarding fetal irradiation should not delay standard trauma imaging.
• •Fixed-ratio blood product replacement strategies during massive transfusion may not be appropriate in advanced pregnancy.

Trauma during pregnancy is a leading cause of maternal mortality in the UK and around the world. Deaths are predominantly attributable to road traffic collision (RTC), violent suicide, and homicide.1, 2, 3 It presents unique and complex management challenges requiring prompt and wide-ranging multidisciplinary input to optimise outcomes.

Clinical decision-making in such scenarios is complicated by many factors:

• (i)The needs of both mother and fetus must be considered.
• (ii)Multiple and dynamic anatomical and physiological changes of pregnancy mandate modification of trauma management principles.
• (iii)Life-threatening obstetric complications can occur even after seemingly minor trauma and may require urgent delivery of the fetus.³
• (iv)Fetal injury can predominate over that of the mother.⁴
• (v)Obstetric teams may be unfamiliar with the emergency department (ED) environment and contemporary management of major trauma.
• (vi)Emergency department and trauma teams may be unfamiliar with aspects of emergency obstetric care, as this usually takes place in dedicated areas distant to the ED.

The great challenges faced by clinicians during management of the multiply injured pregnant patient may explain the findings of a recent large retrospective cohort study in the USA that identified pregnancy as an independent predictor for mortality after trauma.⁵ Pregnant women were found to be 1.6 times more likely to die after trauma than non-pregnant women with traumatic injuries of comparable severity.⁵

Anaesthetists are well placed to facilitate coordination of multidisciplinary care for injured pregnant patients, being familiar with principles of both obstetric and trauma management. Evidence is limited regarding optimal management of trauma during pregnancy, and multiple aspects of contemporary care remain controversial. Specific guidelines have been developed in recent years and are largely based on expert consensus.^6,7 In this article, we will discuss current views on best practice in the initial resuscitation and subsequent care of the pregnant trauma patient. Considerations relating to non-obstetric surgery during pregnancy will not be discussed in detail and have been covered previously in BJA Education.⁸

Epidemiology

Trauma is a leading cause of mortality. On a global scale, it accounts for 10% of all deaths annually, and this is predicted to increase over the coming years.⁹ The UK has seen a progressive decline in morbidity and mortality after trauma over the last decade. This is attributed in large part to the inception of regional trauma networks, increasing experience at major trauma centres (MTCs), and the development of novel clinical approaches to trauma management. Trauma victims who reached English hospitals alive in 2017 had 19% increased odds of survival compared with those in 2008.¹⁰ It is unknown if improvements in survival apply to pregnant trauma patients.

A total of 6–8% of all pregnancies are reported to be complicated by some degree of trauma.¹¹ In the UK, it can be expected that 1 in 100 women of childbearing age suffering major trauma will be pregnant, although this is likely to be an underestimate because of lack of routine screening for pregnancy on admission to the ED.¹² The most common mechanism of injury in these patients is RTC, followed by falls and assault.¹²

Trauma call

The vast majority of patients with major trauma in England will be transferred directly from the scene of injury to an MTC for optimal care. Prehospital services will provide the ED with advanced notification (‘pre-alert’) of their arrival as soon as is practicable detailing patient characteristics, time of injury, mechanism of injury, vital signs, treatment provided, and estimated time of arrival. Specific enquiry should be made at this point to determine the pregnancy status in women of childbearing age. Any suspicion of pregnancy must prompt an urgent request for obstetric and neonatologist support to join the trauma team as they are called to the ED before the arrival of the patient. This is of particular importance if the receiving centre does not have on-site obstetric services to allow adequate time to organise.

A senior ED doctor will usually act as team leader and facilitate preparative discussions regarding what interventions the patient may require based on the pre-alert information. The team leader will then assign roles to the wider team in order that a synchronous approach to assessment and management of trauma can be taken that equally prioritises the logical provision of organ system support and intervention, alongside urgent control of catastrophic haemorrhage (i.e. primary survey ‘<C> ABCD approach’).^13,14 The standard sequence of events and usual actions of the majority of the trauma team will be altered to some degree to meet the needs of the pregnant trauma patient (Table 1). Obstetric specialists must play a key role in the preparatory period to identify and discuss these issues with the wider team before the patient's arrival in the hospital.

Table 1.

Trauma call: typical sequence of events, usual actions of the trauma team and modifications required when trauma affects pregnant patients.¹⁴ ∗Typical role allocations: ED consultant (team leader); ED specialist trainee (performs primary survey); senior anaesthetist (airway management and vascular access); operating department practitioner (assists the anaesthetist); senior orthopaedics and general surgeons (specialty-specific advice and intervention); trauma nurse coordinator (scribe; ED nurses ×2 [team task support]); healthcare assistant (runner); radiographer (bedside radiographs).

Sequence of events	Usual actions of the trauma team	Modifications required for the pregnant trauma patient
Pre-alert	Information transfer	If childbearing age, active enquiry regarding pregnancy status and gestation
Trauma call (T–15 min)	Team assembly and briefing	Urgently request obstetric and neonatology attendance. Discuss standard care modification.
	Team leader assigns roles∗	Manual uterine displacement and fetal heart rate assessment (nurse/midwife)
		Resuscitative hysterotomy team (obstetrics)
		Neonatal resuscitation team (neonatology)
	Preparation of equipment and drugs	Resuscitative hysterotomy pack preparation
		Neonatal resuscitation equipment preparation
		Contact haematology and transfusion laboratories to ensure awareness of pregnancy and gestation.
Patient's arrival (T+0 min)	Rapid assessment: ensure airway patent, central pulse, and absence of catastrophic bleeding before handover.	Ensure immediate and continuous uterine displacement if gestation >20 weeks.
		Structured handover from pre-hospital team to include details of gestation if available.
Immediate management and ongoing review (T+0–15 min)	Primary survey: concomitant assessment and intervention (<C> ABCD)	Team raises index of suspicion for cardiorespiratory decompensation and pelvic fracture, and acts accordingly. Team ensures thoracic decompression performed at appropriate level.
		Assessment to include fetal heart rate and examination for obstetric complications.
		Urgent request for coagulation thromboelasticity assay results and input from haematologist.
		KBT and Clauss fibrinogen to be added to usual blood test requests.
		Team to determine whether permissive hypotension and fixed-ratio blood product replacement are appropriate strategies relative to gestation and likely source of bleeding.
	Cardiopulmonary resuscitation	If gestation >20 weeks, ensure manual uterine displacement and prepare for resuscitative hysterotomy within 4 min of cardiorespiratory arrest.
Situational update (T+15 min)	CT vs DCS	Appreciation that single trauma CT carries minimal risk to fetus and is entirely appropriate where indicated. DCS may require delivery of the fetus and mandates obstetric presence.
	Secondary survey if stability achieved	Must include full obstetric and fetal assessment to identify covert complications.
Command huddle (T+20–30 min)	Senior level team discussion regarding next steps	Team to determine whether early delivery of the fetus is required to improve maternal outcome and appropriate location for definitive surgery if needed. If stability is achieved without need for further intervention, discuss admission to critical care vs maternity ward.

Initial assessment and resuscitation

The anatomical and physiological changes that occur as pregnancy advances mandate multiple modifications to trauma management principles (Table 2). It is therefore essential that all women of childbearing age who suffer trauma are considered pregnant until proven otherwise by testing for urinary human chorionic gonadotrophin or ultrasound (US) scanning. Clinical suspicion of pregnancy may be raised by direct enquiry, clinical examination, and review of the available clinical information whilst definitive confirmation is awaited.

Table 2.

Dynamic anatomical and physiological changes of pregnancy and associated implications for initial trauma management.

System	Changes by full term15	Implications	Management
Airway	↑ Tissue vascularity and oedema ↑ Breast size and neck adiposity ↑ Intra-gastric pressure ↓ Oesophageal sphincter tone	Difficult laryngoscopy and intubation High risk of regurgitation Airway bleeding more likely Difficult FONA	Difficult Airway Society guidelines.16 Early rapid sequence induction. 30° head up. Remove neck collar and provide manual in-line stabilisation. Avoidance of nasal or blind airway interventions. Longitudinal incision during FONA may help identify an impalpable cricothyroid membrane.
Breathing	↓ FRC (30%) ↑ Oxygen consumption (60%) ↑ Minute ventilation (50%) ↓ Arterial CO2 tensions (4kPa) Diaphragm raised 4cm	Precipitous hypoxaemia may develop as a result of respiratory compromise or apnoea. High normal PaCO2 represents hypoventilation. Iatrogenic diaphragmatic / visceral injury. Thoracic trauma risks abdominal organ injury.	Liberal O2 supplementation. 30° head up improves FRC. Pre/apnoeic oxygenation techniques before intubation. Aim PaCO2 of 4.0kPa if mechanically ventilated. Place thoracostomy tubes 1-2 spaces higher. High index of suspicion. CT imaging.
Circulation, catastrophic haemorrhage, and cardiac arrest	Aortocaval compression: ↓Preload, ↑afterload ↓Supine cardiac output (30%) ↓Supine uteroplacental perfusion High cardiac reserve: ↓ Systemic vascular resistance ↑ Cardiac output ↑ Blood volume (40%) Loss of uterine autoregulation Haematological changes: Hypercoagulability Physiological anaemia Physiological thrombocytopaenia	Once fundal height reaches umbilicus aortocaval compression becomes significant and reduces cardiac output when supine. Blood loss of 1.5L or more (at term) may occur before signs of hypovolaemia develop at which point there is an increased risk of cardiac arrest. Dilatation of uterine and pelvic vessels – potentially catastrophic bleeding after injury. Uteroplacental perfusion relies upon maternal mean arterial pressure. Altered interpretation of laboratory blood tests and consumption of clotting factors depending on source of haemorrhage and gestation.	Continuous uterine displacement: manual preferred over tilt as it maintains spinal alignment and allows for effective cardiopulmonary resuscitation. Resuscitative hysterotomy within 4 minutes of cardiac arrest. High index of suspicion; early arterial line; fetal assessment to provide information regarding maternal volume status and obstetric haemorrhage; improvised pelvic binder may be necessary; damage control may not be possible without emptying uterus. Consider appropriateness of restrictive fluid replacement strategy. Avoid vasopressor use. Early haematology input; frequent point-of-care and coagulation tests; individualised clotting factor and fibrinogen replacement strategy; aim fibrinogen >2gL-1; activated partial thromboplastin time and prothrombin time ratios <1.5; platelets >100 x 109L-1.
Disability (neurological)	↑ Neck adiposity	Impossible placement of cervical collar.	Continuous manual in-line stabilisation.
Exposure and environment	Uteroplacental haemorrhage	Concealed haemorrhage may be revealed by vaginal blood loss.	Ensure assessment for per vaginal blood loss during primary survey.

After confirmation of pregnancy, an estimate of gestational age must be made to inform subsequent management. Palpation of fundal height provides a crude, but clinically relevant estimate of gestation in the absence of definitive information. The fundus can be palpated projecting above the level of the pubic symphysis as the second trimester commences, at which point many of the physiological changes of pregnancy are beginning to become apparent. Once the fundus has reached the level of the umbilicus, corresponding with a gestational age of 20 weeks in a singleton pregnancy, aortocaval pressure becomes clinically significant and will require immediate relief by means of uterine displacement as the patient arrives in the ED.¹⁵ Increases in fundal height above the level of the umbilicus approximate to 1 week's gestation for every centimetre advanced cephalad.

The prime objective of initial management must be resuscitation and stabilisation of the mother. Prompt management of maternal hypoxaemia and hypotension will optimise oxygen delivery to the fetus and improve the odds of a favourable fetal outcome.

Airway and spinal immobilisation

The initial focus of management, alongside control of catastrophic haemorrhage, is to ensure airway patency and security whilst maintaining spinal immobilisation as indicated. It is well recognised that obstetric airway management is increasingly difficult as pregnancy advances into the second trimester and beyond, with increased rates of failed intubation owing to tissue oedema, difficult laryngoscopy, and potential for airway soiling.¹⁷ This will be further compounded by the presence of neck and spinal immobilisation, airway trauma, and facial burns. Mortality after failed intubation in obstetrics approaches 1%, significantly higher than in non-obstetric patients, and is usually secondary to aspiration of gastric contents.¹⁷ If airway problems are present or anticipated, early intubation is therefore appropriate and allows time for planning and preparation to reduce risk. Modified rapid sequence induction should be performed by an experienced anaesthetist and follow guidelines from the Difficult Airway Society and Obstetric Anaesthetists' Association.¹⁶ Induction drugs and neuromuscular blocking agents must be tailored to the individual circumstances, accounting for haemodynamic instability and maternal comorbidity.

Careful positioning and preoxygenation are essential before induction. A 30° head-up tilt improves functional residual capacity (FRC) and associated oxygen stores whilst reducing aortocaval compression. It also reduces regurgitation risk and results in caudad breast movement facilitating laryngoscope insertion. If spinal immobilisation is necessary, the whole trolley is tilted head up to achieve similar results. Cervical collar removal, with alternative provision of manual in-line stabilisation, is recommended before induction to allow for effective laryngoscopy. Apnoeic oxygenation techniques are advocated and will attenuate precipitous desaturation after induction. This may be achieved through a combination of maintenance of airway patency, provision of 10 cmH₂O continuous positive airway pressure via a tightly fitted face mask, and supplemental oxygen flow through nasal cannulae. However, high-flow (>15 L min⁻¹) nasal cannula techniques are contraindicated in patients with possible base of skull fracture, nasal fracture, or epistaxis.

If intubation efforts fail, maternal oxygenation must be prioritised. Prompt placement of a second-generation supraglottic airway device may allow time for alternative intubation techniques or a less pressured environment, in which to perform front-of-neck access (FONA). Adipose tissue and oedema can make FONA challenging in obstetric patients, and a longitudinal incision before blunt finger dissection may be required to allow identification of the cricothyroid membrane.¹⁶

Breathing

Respiratory compromise often provokes rapid development of maternal hypoxaemia, owing to increases in demand and reductions in supply of oxygen that develop during the second and third trimesters. Initial provision of high-concentration oxygen supplementation is therefore recommended.⁷ Supplemental oxygen concentrations may subsequently be titrated down, targeting oxygen saturations of 94% or above, thereby avoiding the negative consequences of hyperoxaemia whilst ensuring sufficient uteroplacental oxygen gradient to maintain adequate oxygen transfer to the fetus.⁷

Haemodynamic instability and severe respiratory compromise secondary to haemopneumothorax warrant immediate thoracic decompression.¹³ As pregnancy advances, cephalad displacement of abdominal viscera and the diaphragm occurs.^7,15 To avoid iatrogenic injury, thoracostomy tubes should be placed one to two spaces above the usual fifth intercostal space within the safe triangle.^3,7 If time allows, preliminary US scanning will provide reassurance of suitability of insertion site and may assist in confirming diagnosis. CT has a higher sensitivity than US when diagnosing haemopneumothorax, and is recommended before decompression in the absence of maternal instability, thereby reducing unnecessary intervention and associated complications. Nevertheless, if clinical suspicion is high, appropriate measures must be taken to allow urgent performance of decompression during transfer in case subsequent deterioration occurs.¹³

Circulation

Gestations more than 20 weeks mandate immediate relief of aortocaval pressure either by manual uterine displacement or left lateral tilt of the patient from the moment she arrives in the ED.¹⁵ Two large-bore cannulae must be inserted promptly. If i.v. access is difficult, intraosseous access should be sought urgently, followed by central venous access once time allows. Routes for drug administration are ideally placed above the level of the diaphragm to allow entry into the central circulation without impedance caused by caval compression.

Standard venous blood tests must be arranged urgently (group and save or cross-match, full blood count, urea and electrolytes, liver function tests, coagulation screen, and Clauss fibrinogen). Point-of-care testing (POCT), including measurement of arterial blood gases, acid–base balance, thromboelasticity assays, haemoglobin, electrolyte, and lactate concentrations, will allow appropriate and expeditious treatment. Interpretation of results must be relative to expected changes associated with advancing pregnancy.¹⁵ Early insertion of an arterial line is recommended when compromised cardiorespiratory function is expected and will allow rapid identification of decompensation and facilitate ongoing POCT.

The Kleihauer–Betke blood test (KBT) should also be sent to provide an indication of the degree of fetomaternal haemorrhage after uteroplacental injury. It allows correct dosing of anti-D immunoglobulin to be calculated for rhesus (Rh)-negative mothers exposed to Rh-positive blood. It also indicates the severity of uteroplacental haemorrhage and assists in fetal prognostication after major trauma, regardless of Rh status.^3,7

Catastrophic haemorrhage

Contemporary management of traumatic haemorrhage prioritises early identification of the source of bleeding, provision of rapid haemostasis, and efforts to prevent deterioration to coagulopathy. The urgent need to achieve rapid haemostasis after trauma is compounded by pregnancy. The index of suspicion for haemorrhage must be high, as circulatory decompensation presents increasingly late and precipitously as pregnancy advances into the second trimester, owing to increases in cardiac output and blood volume that develop. During the third trimester, 1.5 L blood or more may be lost before clinical signs of hypovolaemia present; at this point, the pregnant patient is at even higher risk of progressing to cardiac arrest than the non-pregnant patient.

Early identification of bleeding sources allows for rapid and appropriate intervention, and is achieved through a combination of systematic examination, bedside investigation, and trauma series CT during the primary survey. Abdomino-pelvic examination must be modified during the primary survey to specifically seek out clinical evidence of placental abruption (common) and uterine rupture (rare), which may be a significant source of concealed non-compressible haemorrhage even after seemingly minor trauma (Table 3). Pelvic fractures are of extreme concern, and thresholds for intervention during the primary survey must be even lower than in non-pregnant patients. They may result in injury and laceration to an increasingly dilated pelvic vasculature, the highly perfused uterus or the fetus, and result in rapid exsanguination. Pelvic binders must be applied immediately if pelvic fracture is suspected and removed only after control of bleeding is achieved.¹³ They sit over the greater trochanters, but may need to be improvised if purpose-made binders cannot be properly applied in advanced pregnancy. Trauma CT imaging provides rapid and accurate identification of bleeding sources, and is entirely appropriate in the stable and injured pregnant patient. The potential benefit to maternal and consequently fetal outcomes achieved through identification and rapid control of haemorrhage outweighs the minimal risk to the fetus secondary to irradiation. If the mother remains unstable despite resuscitation, transfer to CT may not be safe. Bedside investigations, such as plain radiographs and US, can be performed rapidly and may provide useful clinical information to direct emergent intervention appropriately. Fetal assessment and monitoring must also be included within the primary survey. Evidence of fetal distress can support the diagnosis of placental abruption and uterine rupture, or may provide the first indication of impending maternal decompensation attributable to hypovolaemic shock as uteroplacental perfusion is sacrificed in favour of ongoing maternal organ perfusion.

Table 3.

Obstetric complications after traumatic injury: presentation, diagnosis, and management.

Complication	Clinical presentation	Diagnosis	Management
Fetomaternal haemorrhage (10–30%)7	Variable depending on cause Fetal distress Fetal demise	Clinical Imaging Abnormal CTG KBT	Management depends on cause and severity of presentation. KBT results allow Rh immunoglobulin dose determination for Rh –ve mother carrying Rh +ve fetus, and may also act as an indicator for severity of trauma.
Placental abruption (5–50%)3,7	Majority present within 2–6 h. May be asymptomatic or follow minor trauma Abdominal (anterior) or back pain (posterior) Uterine tenderness and rigidity; preterm labour, vaginal bleeding, and haemodynamic instability Fetal distress and death	Clinical: difficult if concealed Abnormal CTG: fetal distress and contractions US: poor sensitivity CT: more appropriate in context of trauma	Maternal resuscitation Early fetal delivery if fetal compromise or maternal instability
Uterine rupture (rare)7	Usually after direct trauma in advanced gestation Severe abdominal pain and distension, uterine rigidity, haemodynamic instability, palpable, and freely mobile fetal parts Fetal distress and death (approaches 100%)	Clinical Abnormal CTG: fetal distress US	Maternal resuscitation Laparotomy to control haemorrhage and allow fetal delivery
Preterm labour and spontaneous miscarriage	After direct uterine trauma, placental abruption, or traumatic rupture of the membranes Contractions, vaginal bleeding, and pelvic pressure	Clinical Abnormal CTG: contractions Fibronectin test	Tocolytics are not recommended after traumatic initiation of preterm labour, as it represents pathology. Maternal corticosteroid administration if gestation 24–34 weeks and delivery imminent Magnesium sulphate for fetal neuroprotection if gestation <32 weeks; neonatal support
Pelvic fracture	Pelvic pain Haemodynamic instability Fetal distress and death: fetal injury more likely if head engaged	Clinical Imaging	Pelvic binder Damage control: interventional radiology or open surgery Conservative management or surgical fixation If stable fracture, future vaginal delivery is appropriate3

Modern trauma principles in the non-obstetric patient advocate a restrictive fluid replacement and blood-product-based approach to resuscitation of haemorrhagic shock, permitting a degree of hypotension whilst titrating therapy to a palpable central pulse, for the minimum time period possible until control is achieved.¹³ Rapid restoration of preinjury blood volume and pressure is thought to risk clot disruption and development of coagulopathy, and can therefore lead to further haemorrhage. Crystalloid infusion is now avoided during the early resuscitation of trauma patients in favour of blood products. Crystalloids may exacerbate bleeding and reduce oxygen delivery to the tissues as a result of the unintended and diametric development of haemodilution, coagulopathy, and hypothermia.¹³ Restrictive fluid replacement strategies are a source of controversy in pregnant patients, as they may result in reduced uteroplacental perfusion and fetal compromise, and an increased potential for sudden and rapid maternal deterioration to cardiac arrest. The primary objective of ensuring maternal well-being must be remembered, and careful consideration by the multidisciplinary team will help guide appropriate management. Factors, such as the severity of maternal injury and haemorrhage, fetal condition and viability, and amenability of bleeding points to rapid control, must be considered.

Multiple injuries and hypovolaemic shock in the pregnant patient are most appropriately managed aggressively using contemporary principles, accepting that a period of reduced uteroplacental perfusion, fetal compromise, or delivery of the fetus may be required to allow maternal survival. Clearly, if fetal demise has occurred or is highly likely, these decisions are simplified. In cases of isolated injury, such as external haemorrhage, amputation, and limb fracture where the mother remains stable and bleeding can be rapidly controlled through compression, use of a tourniquet or by bone reduction permissive hypotension may not be necessary. A more appropriate plan in these circumstances would aim to restore maternal arterial blood pressure to pre-injury levels with blood-product-based resuscitation to maintain uteroplacental perfusion and prevent unnecessary fetal compromise.

Mothers who remain stable after initial resuscitation will require definitive control of the sources of bleeding identified during CT scanning, and this may involve delivery of the fetus to manage haemorrhage and provide the viable fetus with the best chance of a favourable outcome. Those who remain unstable or go on to develop the alarming triad of acidosis, coagulopathy, and hypothermia will require damage control resuscitation. The aims of which are to provide rapid control of haemorrhage and management of peritoneal soiling through emergency surgery or intervention to achieve stability as soon as possible, alongside medical efforts to replace blood loss, prevent coagulopathy, and maintain adequate maternal organ perfusion. Exploratory thoracic and abdominal surgery may need to be performed with limited information on the source or number of bleeding points. The obstetric team must be present at the time of exploratory surgery in case emptying of the uterus and delivery of the fetus are necessary to achieve haemostasis and maternal stability. Emptying of the uterus is indicated in cases of penetrating uterine injury, placental abruption, and uterine rupture, and to allow surgical access for control of alternative sources of pelvic and abdominal haemorrhage.

Medical management of haemorrhagic shock should continue whilst efforts are made to achieve haemostasis. Early activation of major haemorrhage protocols is essential to ensure availability of blood products. O negative blood must be used until group and Rh status is determined. Rapid infusers and blood warming devices should be available and prepared for use. Where blood is not immediately available, small boluses of warmed crystalloid are appropriate and should be targeted to the desired response, only until blood arrives. Hypocalcaemia and hyperkalaemia must be actively sought during massive transfusion, and be corrected in a timely manner to maintain coagulation and prevent associated haemodynamic instability. Tranexamic acid (1 g i.v.) is thought to be safe during pregnancy and confers survival benefit if given within 3 h of injury.^18,19

Vasopressor use to treat hypotension risks clot dislodgement and may encourage further bleeding whilst simultaneously reducing uteroplacental perfusion. Vasopressors should be reserved for patients in whom evidence of inadequate organ perfusion is present and where there is a failure in response to further volume administration.

Standard fixed-ratio blood product replacement protocols to prevent the development of coagulopathy during massive transfusion may be harmful after trauma in pregnant women, once the hyper-coagulable state of advanced pregnancy develops. It is important to note that circulating fibrinogen concentrations increase significantly as pregnancy advances into the second trimester and beyond, and that these concentrations eventually reach a point at which they exceed those present in fresh frozen plasma (FFP). Furthermore, studies relating to peripartum haemorrhage have demonstrated that rapid consumption of fibrinogen often occurs with relatively little decrease in clotting factor concentrations despite the significant volumes of blood lost.²⁰ Unnecessary administration of FFP in these circumstances will likely result in unintended dilution of fibrinogen concentrations and worsening coagulopathy, and risk the development of transfusion-associated circulatory overload, pulmonary oedema, and transfusion-associated acute lung injury to which the pregnant patient is particularly prone. Fibrinogen concentrations <2 g L⁻¹ before delivery of the fetus have been demonstrated to have a 100% positive predictive value for subsequent development of severe postpartum haemorrhage (PPH) in advanced pregnancy.²⁰ Fibrinogen concentrations that fall within the normal range for non-pregnant patients may therefore represent onset of disseminated intravascular coagulopathy (DIC) in advanced pregnancy, and must be appreciated and corrected aggressively to maintain a fibrinogen concentration >2 g L⁻¹.^7,20

Although evidence relating to PPH cannot be directly extrapolated to early pregnancy or severe non-obstetric haemorrhage, there remains a need to tailor blood product replacement to the individual circumstances, taking into account the stage of pregnancy and the severity and source of haemorrhage. Standard fixed-ratio major haemorrhage transfusion protocols are appropriate for non-obstetric haemorrhage in early pregnancy. As pregnancy advances and particularly in cases of traumatic obstetric haemorrhage, the early use of cryoglobulin precipitate or fibrinogen concentrate will often be more appropriate than use of FFP. This is of extreme importance if fibrinogen levels are falling and emptying of the uterus is planned to avoid subsequent progression to severe PPH and DIC. Regular clotting studies, point-of-care viscoelastic assays, and early involvement of obstetric haematology expertise are essential to guide ongoing blood product replacement appropriately.

Maternal cardiac arrest

Cardiac arrest is managed according to adult life support principles, but must be modified once gestations of 20 weeks or more have been reached to include uterine displacement and resuscitative hysterotomy. Immediate manual uterine displacement is preferred over left lateral tilt in these circumstances, as it allows for more effective cardiac compression.⁷ Resuscitative hysterotomy should be performed within 4 min of arrest.³ It relieves aortocaval pressure, improves respiratory dynamics, and provides placental auto-transfusion, thereby optimising chest compressions, oxygen delivery, and cardiac output simultaneously.^3,15 It also provides the best chance of fetal survival if a viable gestational age (24 weeks) has been reached.

Resuscitative hysterotomy should be performed in the location that cardiac arrest occurs by the most appropriately experienced member of the trauma team, ideally an obstetrician, and requires only basic equipment. Prompt support from midwives and neonatologists must be available to provide neonatal resuscitation to the viable fetus. Successful restoration of maternal circulation will require subsequent transfer to operating theatre for laparotomy and stabilisation. Traumatic cardiac arrest associated with abdominal or thoracic injury may also mandate simultaneous emergency thoracotomy, clearly creating difficult logistical issues.

Disability (neurological)

Level of consciousness and pupillary reactions to light are assessed to identify evidence of brain injury and determine the need for airway protection. Suspected traumatic brain injury requires measures to maintain cerebral perfusion pressure and oxygen delivery to prevent secondary insult. Head-up tilt, maintenance of adequate mean arterial pressure and oxygenation, avoidance of venous congestion at the neck, and control of Paco₂ may be needed. If both haemorrhage and head injury are present and it is thought that head injury is the dominant condition, then a less restrictive volume replacement strategy is recommended, in order that adequate cerebral perfusion pressure is prioritised.¹³

Intracranial hypertension and associated brain herniation will necessitate maternal hyperventilation, allowing hypocapnia and alkalosis to develop, resulting in intentional cerebral vasoconstriction and reduction in intracranial blood volume and pressure. These measures may be at the expense of fetal oxygenation. Maternal alkalosis also results in uterine vasoconstriction and left shift of the maternal oxygen dissociation curve, thereby reducing uteroplacental oxygen transfer.¹⁵

The precautions for spinal injury must be reassessed. Correct placement of cervical collars might be impossible because of neck oedema, adipose tissue, and large breasts, and requires continuous provision of manual in-line stabilisation. Spinal boards should be removed as soon as appropriate.

Blood glucose concentrations are monitored, as control may be required. Hyperglycaemia is associated with poor prognosis after head injury, and hypoglycaemia must be prevented to allow adequate glucose transport to the fetus.

Exposure and environment

Hypothermia must be prevented to avoid coagulopathy and further bleeding. It will also prevent shivering and resultant increases in oxygen demand. The use of warming devices and blankets and removal of wet clothes may be necessary. Particular attention should be made to identify concealed injury or haemorrhage during exposure of the patient, including an assessment for vaginal blood loss.

Trauma imaging

Radiological investigations, if clinically indicated, must be undertaken without delay. Pregnant patients with high-risk mechanisms of injury often have appropriate imaging withheld because of concerns relating to fetal irradiation and exposure to i.v. contrast.²¹ This can result in diagnostic and therapeutic delay, potentially resulting in serious consequence for both mother and fetus.

A single trauma series CT scan is not thought to increase the risk of fetal developmental problems (miscarriage, prematurity, teratogenesis, growth retardation and neurological conditions).^7,22 However, radiation effects are cumulative, and efforts must be made to minimise unnecessary or repeated exposure. Early input from radiology colleagues is therefore recommended. I.V. iodinated and gadolinium-based contrast agents appear to be safe in pregnancy and are essential to identify areas of internal haemorrhage.²³

The use of extended focused assessment with sonography for trauma (eFAST) US scans and plain radiographs is appropriate during initial resuscitation efforts in unstable patients to identify intraperitoneal haemorrhage, pericardial effusion and haemopneumothorax, and to determine appropriate intervention and damage control surgery (DCS).¹³ However, eFAST scans will provide increasingly limited information with advancing gestation, as the gravid uterus may obscure the desired imaging target. Trauma series CT is the gold standard in stable and fluid-responsive patients, and will guide definitive surgery. It is worth noting that the diagnosis of placental abruption is significantly improved after CT compared with US.²⁴ As placental abruption may occur even with seemingly minor trauma, there should be a lower threshold to performing abdominal CT in pregnant patients after trauma.

Diagnostic peritoneal lavage (DPL) has largely been superseded by CT and US. DPL risks visceral injury and may lead to unnecessary surgery in patients where CT imaging suggests conservative management to be appropriate.

Mechanisms and patterns of injury during pregnancy

Road traffic collision

Road traffic collisions account for more than half of all maternal trauma.¹² Intrauterine shear forces and the contrecoup mechanism associated with rapid deceleration can result in placental abruption or uterine rupture in the absence of other obvious injury. Incorrect use or non-use of seatbelts increases the risk of such injuries.

Falls

Low-height falls are common in pregnancy, particularly during the third trimester, as altered centre of gravity develops.³ The majority of falls do not result in significant injury although in rare cases, shear forces or direct abdominal trauma may result in obstetric complications.

Physical assault and self-inflicted violence

Around 8% of females experience some form of domestic abuse.²⁵ Many women are assaulted for the first time during pregnancy and are at an increased risk of progression of pre-existing abuse to homicide whilst pregnant and postpartum.^2,26 Homicide is usually perpetrated by a partner or family member, and is violent in nature (stabbing, strangulation, and blunt head injury).^2,26 The abdomen is most commonly targeted, followed by the genital area, potentially resulting in both maternal and fetal injury. A vague history of mechanism of injury during pregnancy raises suspicion of domestic violence and should prompt referral to the safeguarding team according to local protocols.

Suicide attempts are more often by violent means during pregnancy.² Common mechanisms include hanging, falling from a height and stepping into the path of a vehicle.²

Burns

Burn and inhalational injuries are rare in pregnancy.³ Evidence of maternal airway burn requires expeditious intubation before further oedema renders this impossible. Significant burns result in major fluid shift and insensible loss requiring urgent correction to maintain organ and uteroplacental perfusion. Hypoxaemia secondary to smoke and toxin inhalation must be identified and managed urgently to maintain oxygen delivery to mother and fetus. Remember that the abdomen in late pregnancy represents an increased proportion of total body surface area, which may lead to underestimation of burn area if abdominal burns are present. All pregnant patients with significant burns should be transferred to a tertiary burns care unit with available obstetric services as soon as feasible.³ Maternal burns of more than 40% indicate a poor fetal and maternal prognosis, and increase the strength of the argument for early fetal delivery.³

Blunt vs penetrating trauma

The vast majority of trauma in both pregnant and non-pregnant patients is blunt. However, there is a higher incidence of penetrating trauma in pregnant patients compared with their non-pregnant counterparts (5–10% vs 2%).^3,5,12 This may be explained by the increased likelihood of violent assault and self-harm during pregnancy. Both maternal and fetal mortality rates are increased after penetrating trauma.^4,5

The consequence of either blunt or penetrating trauma depends on the site of injury and the gestational age. As the uterus rises into the abdomen, the abdominal viscera are shifted posterior and cephalad. The gravid uterus may therefore protect other maternal viscera after anterior abdominal trauma, at the expense of uterine and fetal injury. Thoracic trauma can result in unexpected and easily missed gastrointestinal, splenic, or hepatic injuries. Pelvic trauma and fracture may not only result in catastrophic haemorrhage, but are also highly likely to result in uterine or fetal injury, with an associated poor fetal outcome.³

Obstetric assessment and management

Where stabilisation of the injured pregnant patient is achieved without the need for obstetric intervention, an urgent and thorough obstetric and fetal assessment must be performed during the secondary survey to ensure prompt identification and management of obstetric complications (Table 3). The viability of the pregnancy can be confirmed by fetal heart auscultation in early pregnancy. After 26 weeks' gestation, cardiotocographic (CTG) monitoring will provide useful information relating to both fetal well-being and uterine activity. Non-reassuring fetal heart rate patterns and early contractions may indicate maternal pathology, such as direct uterine trauma, uterine rupture, and placental abruption that were not apparent during initial assessment and resuscitation. Ultrasound examination allows an estimation of gestational age, may diagnose uteroplacental pathology and fetal injury, and provides important information on placental localisation.

The ideal period of CTG monitoring is uncertain. A practical and evidence-based approach is to continue intermittent monitoring for 4 h initially, extended to 24 h if any of the following are present: contractions of more than one every 10 min, uterine tenderness, significant abdominal pain, ruptured membranes, vaginal bleeding, a positive KBT, or a non-reassuring fetal heart rate pattern.^3,7

The decision on whether to continue pregnancy compared with early delivery after trauma will depend upon the degree of fetal maturity, presence of uteroplacental and fetal injury, severity of maternal trauma, and any implications of continuing pregnancy on maternal prognosis. The optimal location for early delivery will depend on the circumstances. If the fetus is viable and the mother appropriately resuscitated and stabilised, then obstetric theatres may be considered for best access to obstetric and neonatal support. Conversely, if the mother remains unstable or requires additional intervention, then general operating theatres or the ED may be more appropriate to minimise delays attributable to transfer and to ensure best access to specialist support. If maternal outcome is unlikely to be significantly affected, then pregnancy should be continued as far as is possible to improve the chance of optimal fetal outcomes. These decisions require careful consideration and input by the wider multidisciplinary team.

If pregnancy is unaffected and no complications are apparent, then the patient may be discharged from obstetric care. The patient should be warned of the risks of preterm labour and advised to return for urgent obstetric assessment if abdominal pain or vaginal bleeding occurs. Ongoing management of injuries should be as for the non-obstetric patient. Particular care must be taken to assess the need for venous thromboembolism prophylaxis after trauma, as pregnancy is in itself a prothrombotic state.¹⁵ Obstetric follow-up should continue as usual until delivery. The mode of delivery will depend on the patient's preferences, obstetric considerations, and any residual effects of the trauma (such as a major pelvic fracture). Patients may also need psychological support and counselling after major trauma, especially if they have encountered fetal loss.

Education and training

Given the relative rarity and potential complexity of trauma care in the pregnant patient, we recommend development of clear local protocols and regular multidisciplinary training and simulation in order that best care can be provided during such scenarios.

Future directions

Maternal deaths secondary to trauma, such as RTC, are currently classified as coincidental deaths (i.e. unrelated to pregnancy). We argue that the sequelae of trauma are aggravated by the physiological effects of pregnancy and that associated deaths should therefore be classified as indirect, in order that they be subject to thorough review of care and lessons may be learned from such unfortunate circumstances.

Declaration of interests

The authors declare that they have no conflicts of interest.

MCQs

The associated MCQs (to support CME/CPD activity) are accessible at www.bjaed.org/cme/home by subscribers to BJA Education.

Biographies

Tom Irving FRCA is a consultant anaesthetist at the Royal Liverpool and Broadgreen University Hospitals NHS Trust. His areas of interest are obstetric and regional anaesthesia and education. He acts as lead anaesthetist for simulation and instructs on the MOET course.

Rashmi Menon MD FRCA is a consultant anaesthetist at Leeds Teaching Hospitals NHS Trust. Her areas of interest are obstetric anaesthesia, major trauma, and education. Until recently, she was lead anaesthetist for trauma and has contributed to development of national and local trauma guidance.

Etienne Ciantar MD MRCOG FHEA is a consultant obstetrician at Leeds Teaching Hospitals NHS Trust. His areas of interest are high-risk obstetrics, obstetric haematology, education, and research. He has published several articles on obstetric haematology.

Matrix codes: 1B04, 2A02, 3B00