Trauma in pregnancy

Epidemiology

• 8% of all pregnancies
• Minor injuries can cause major obstetric disruption
• Consider domestic violence in all cases
• Perform pregnancy testing in all women of childbearing age who suffer trauma
• Presume viability if unknown gestation
• Blunt trauma in 82%
• Direct fetal injuries occur in <1% of severe blunt trauma vs. 70% of penetrating abdominal trauma

Principles

• Follow ATLS guidelines
• First priority is the woman
• Early obstetric +- neonatology involvement
• Recognise anatomical/physiological differences
• Thoroughly assess all pregnant women even after minor trauma

Common pitfalls
Failure to:

• Suspect or recognise shock in presence of normal vital signs
• Suspect or recognise abdominal injury if normal examination
• Suspect partner violence
• Treat shock aggressively with blood products
• Recognise and treat supine hypotension syndrome
• Conduct necessary imaging due to perceived risk to fetus
• Observe and monitor all minor trauma with CTG for 4 hours minimum if >24 weeks
• Detect early pregnancy
• Test for RhD status and administer anti-D
• Initiate perimortum C-section within 4-6 minutes of no response to effective CPR

Increased risk of:

 – Foeto-maternal haemorrhage

 – Preterm labour

 – Placental abruption

 – pregnancy loss

 – DIC

 – Uterine rupture

MVA most common cause of blunt abdominal trauma (70%)

 – High speed >80kph and broad-side MVA are highest risk

Falls and direct assault are next

Fetal death far more common than maternal

ISS >12 = 65% fetal death rate vs. ISS <12 = 0% in one study

Physiology of pregnancy

• Maternal blood volume expansion from week 10 and peaks at 45% increase at week 28
• Mild physiological anaemia – Hct falls by 31-35% by end of pregnancy
• CO increases 1-1.5L/min at week 10 and remains elevated until end of pregnancy
• HR increased 10-20/min in second trimester with decreased SBP and DBP by 10-15mmHg (BP returns to normal by third trimester)
• Pregnant patient may lose 30-35% of blood volume without manifesting hypotension or clinical signs of shock
• Uterine blood flow directly proportional to maternal MAP so aggressively resuscitate to maintain this
• Uterus is intra-abdominal from week 12 and thus susceptible to direct trauma
• Uterine blood flow up to 600mL/min
• Passive stretching of abdominal wall and peritoneum reduces sensitivity to intraperitoneal blood
• From weeks 18-20, mother at risk of supine hypotension syndrome
• Dilatation of renal pelvis and ureters from week 10. Bladder intra-abdominal and susceptible to trauma

Physiology of pregnancy

• Diaphragm rises as much as 4cm
  • Consider this in ICC placement
• Vt increases 40% and residual volume reduces by 25%
  • Can lead to rapid desaturation
• Gastric emptying delayed and GOJ sphincter tone reduced – increased risk of aspiration
• Most common cause of intra-abdominal bleeding is splenic injury as in non-pregnant patients
• ECG left axis deviation by 15 degrees, TWI or flattening in III, V1 and V2 and Q waves in III, aVF
• Coagulation factors (fibrinogen, VII, VIII, IX, X) all increase increasing risk of thrombosis
• Buffering capacity of blood is reduced (reduced Hct)
• ALP can triple due to placental production

Introduction

• Direct trauma more likely to cause injury to spleen/liver/fractures
• Indirect shear forces more likely to cause placental abruption
• Pelvic pain, uterine contractions, PV bleeding can all indicate placental abruption

Introduction

• Increase volume resuscitation by 50%
• Wedge under right hip over 20 weeks
• USS
  • E-FAST if indicated (sensitivity and specificity similar to non-pregnant patients), then FHR and fetal activity
• Radiographs
  • Highest risk to fetal viability is in first 2 weeks
  • Highest risk for malformation is weeks 2-8 (embryonic organogenesis)
  • CNS teratogenicity highest weeks 8-15
  • A dose >5rad is threshold for human teratogenesis

Special considerations

• Best predictors of fetal loss or adverse outcome are crash severity and lack of, or improper use of, seat belts
• Should be worn as low as possible under gravid abdomen across ASIS and pubic symphysis
• Do not disconnect air bags for pregnant women
  • Benefits outweight any potential risks
• Interpersonal violence
  • Encourage social work involvement for all but the most obvious cases of accidental injury

Trauma in pregnancy – Anti-D

First trimester 250IU

 – Chorionic villus sampling

 – Miscarriage

 – Termination of pregnancy

 – Ectopic pregnancy

 – NOT threatened miscarriage before 12 weeks

Second trimester (625IU)

 – Obstetric haemorrhage

 – Amniocentesis/cordocentesis

 – External cephalic version of a breech presentation

• Abdominal trauma, or any other suspected intrauterine bleeding event

All women who have suffered a potential sensitising event should have Kleihauer testing to determine magnitude and requirement for further Anti-D

 – 100IU covers 1mL of fetal red cells (2mL of whole blood)

Initial stabilisation

• Early obstetric involvement
• Right lateral wedge 15-30 degrees (left lateral position) or manual displacement
• Routinely administer oxygen
• Consider smaller ETT, prokinetic, early orogastric tube insertion
• Chest tubes at 3rd-4^th rib space
• Early MTP initiation
• Consider perimortem CS if 20 weeks gestation or more and no response after effective CPR for 4 minutes

Secondary assessment

• Maintain high index of suspicion for occult shock and abdominal injury
• Assess uterus tone, rigidity, tenderness, contractions
• Assess and record foetal heart rate
• If >= 23 weeks – CTG for 4 hours (cautious interpretation if <28 weeks)
• If any foetal or maternal compromise, assess for:
  • Placental abruption
  • Feto-maternal haemorrhage (Kleihauer)
  • Uterine rupture
  • Premature labour
  • DIC

Secondary assessment

• Consider
  • Rectal examination
  • Pelvic exam (obstetric team)
    • Sterile speculum
    • Assess for ROM, vaginal bleeding, cervical effacement and dilation, cord prolapse and foetal presentation
  • FAST/formal USS
  • Kleihauer for all >=13 weeks
  • Standard trauma bloods + G&H + antibodies, Kleihauer and Coags
  • Consider ROTEM/TEG for all –> Aim fibrinogen >2.5g/L
  • If RhD negative and >12 weeks give anti-D

Discharge criteria

• Obstetric team agree
• Reassuring maternal status
• Normal CTG/FHR for 4 hours minimum
• No contractions
• Blood results checked
• Anti-D provided if necessary
• Social work referral offered

Discharge information

• Signs of preterm labour
• Abdominal pain
• PV loss
• Change in foetal movements
• Advise to inform usual maternity provider of trauma

Estimating gestation

• Gravid uterus to umbilicus = 20 weeks
• Vertical distance from symphysis pubis to top of fundus = weeks gestation in centimetres
• Biparietal diameter (BPD) of 60mm = 24 weeks
• Mark top of fundus to evaluate for rising fundal height in concealed placental abruption

FHR monitoring

• Normal FHR 110-160
• Heard with standard stethoscope from 20 weeks and with Doppler from 12 weeks

Imaging

• Preferable to do single contrast CT than multiple sub-optimal non-contrast CT
• If >1mSv exposure to embryo or fetus must:
  • Be justified on individual basis
  • Include assessment of risks to fetus and woman if performed or not
  • An estimate of expected radiation dose documented
• FAST is just as accurate as in non-pregnant patients

Perimortem C-section

• Aka resuscitative hysterotomy
• Performance within 4-5 minutes of cardiac arrest is widely supported for potential survival of mother +- foetus
• Large vertical abdominal incision
• Uterine incision vertical or horizontal
• Continue CPR during and after procedure

Radiology approximate doses to fetus (mSv)

Trauma in pregnancy – radiology

• Standard plain films <1rad each
• Abdominopelvic CT and angiography result in highest delivered doses of radiation (2.5-3.5 rad each)
• CT detects placental abruption (sensitivity 86% and specificity 98%)
• Contrast can cause neonatal hypothyroidism

Radiology

Trauma in pregnancy – teratogenic effects

Uterine rupture

• More likely with advanced gestational age and severe direct abdominal trauma
• Usually diagnosed on USS
• Presents with severe pain, abnormal CTG, palpable fetal parts, fetal demise, positive FAST, uterine guarding/rigidity, shock and PV bleeding
• Management
  • Urgent C/S
  • Repair
  • Haemodynamic support

Placental abruption

• Most common serious complication of blunt force trauma
• Accounts for 50-70% of trauma-related fetal demise
• Second only to maternal death as cause for fetal demise
• 1-5% of minor injuries in pregnancy and up to 40% of major traumas
• Can occur with rapid deceleration alone
• Can occur following minor trauma
• Most occur within 2-6 hours and almost all within 24 hours
• Presentation
  • Abdominal pain, PV bleeding, uterine contractions, abnormal CTG, uterine tenderness/woody, maternal instability
• CTG > USS in detection
• Management
  • SIgnificant abruption – urgent C/S
  • Consider antenatal corticosteroids between 23+0 and 34+6 weeks
  • Monitor for DIC

Preterm labour

• Definition: >4 uterine contractions per hour accompanied by cervical change at <37+0 weeks
• Cramping pain, pelvic pressure, change in vaginal discharge, PV bleeding

Feto-maternal haemorrhage

• Occurs in 10-30% of pregnant trauma patients
• Presentation
  • Decreased or absent foetal movements
  • Fetal distress (sinusoidal classic CTG indicating fetal anaemia)
  • Women may experience transfusion reaction
• Kleihauer 
  • Negative = <1mL of fetal blood
  • Useful for determining dose of Anti-D but not predictive of outcome
• Flow cytometry is indicated if Kleihauer >4mL and is the most accurate quantitative measure

Amniotic fluid embolism

• Mortality rate 20-60%
• Classic: Respiratory distress, hypoxia, hypotension and coagulopathy
• Other: Maternal hypotension (100%), acute hypoxia, seizures, arrest, haemorrhage, DIC, profound fetal distress
• Management primarily supportive

Trauma in pregnancy – Pelvic fracture

• Most patients can still deliver vaginally
• High-risk of massive internal haemorrhage and damage to uterus, bladder, urethral and ureteric lacerations
• Retroperitoneal haemorrhage occurs and can be difficult to diagnose
• Direct fetal skull fractures can cause fetal death

Last Updated on June 3, 2021 by Andrew Crofton