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Trauma in pregnancy is the leading non-obstetric cause of maternal death, complicating approximately 1 in 12 pregnancies and responsible for 7% of all maternal deaths. The management of the pregnant trauma patient requires simultaneous care of two patients — mother and fetus — with specific anatomical, physiological, and resuscitative considerations that differ substantially from non-pregnant trauma care. Gestational age is the fundamental determinant of uterine position and thus injury risk: at 12 weeks the uterus is palpable at the pubic symphysis and is protected by the bony pelvis; at 20 weeks it reaches the umbilicus; at 36 weeks it is at the xiphoid process. Beyond 20 weeks, the enlarged uterus compresses the inferior vena cava when the patient lies supine (aortocaval compression), reducing venous return and cardiac output by up to 30% — left lateral tilt of 15–30 degrees is mandatory in all pregnant patients beyond 20 weeks unless spinal injury is suspected, in which case manual uterine displacement is used. Fetal monitoring should be initiated as soon as the patient is stabilised for any viable fetus (typically ≥24 weeks gestational age) and continued for a minimum of 4–6 hours after minor trauma and 24 hours if any uterine contractions, haemorrhage, or abnormal fetal heart rate patterns are detected. Placental abruption — traumatic separation of the placenta from the uterine wall — is the most common cause of fetal death from maternal trauma, preceding maternal haemodynamic instability. All Rh-negative pregnant trauma patients must receive anti-D immunoglobulin (RhIG) after any abdominal trauma, and the dose should be guided by a Kleihauer-Betke test measuring fetal red blood cells in maternal circulation.
Uterine fundal height (weeks): Fundus at pubic symphysis = 12 weeks; at umbilicus = 20 weeks; at xiphoid = 36 weeks (approximately 1 cm per week from 20–36 wks); Aortocaval compression threshold: >20 weeks — apply left lateral tilt 15–30°; Fetal monitoring duration: minor trauma ≥4h; any abnormality → 24h; Kleihauer-Betke (KB): normal = <0.003% fetal cells; Anti-D dose = (KB% × maternal blood volume in mL) ÷ 30
- 1Establish gestational age and fetal viability immediately upon patient arrival: confirm dates from patient history, last menstrual period, or prior obstetric records; perform point-of-care ultrasound (FAST exam) to assess fundal height and fetal heart activity; identify gestational age ≥24 weeks as the threshold for fetal monitoring.
- 2Position immediately: apply left lateral tilt of 15–30 degrees (wedge under right hip) or use manual left uterine displacement if spinal trauma is suspected — this relieves aortocaval compression, restoring venous return and preventing maternal hypotension-induced fetal hypoperfusion.
- 3Apply standard ATLS primary survey (ABCDE) with pregnancy-specific modifications: anticipate difficult airway (laryngeal oedema, large breasts); position head up 30 degrees if possible; use RSI for intubation with cricoid pressure (modified for pregnancy); anticipate accelerated desaturation (reduced FRC + increased O₂ consumption).
- 4Recognise physiological differences: normal BP in pregnancy may be 10–15 mmHg lower than pre-pregnancy baseline; normal heart rate is 10–15 bpm higher; haemoglobin is diluted to 10–12 g/dL (physiological anaemia); plasma volume increases 40–50% — maternal vital signs may appear relatively normal despite significant blood loss before fetal compromise is apparent.
- 5Initiate electronic fetal monitoring (cardiotocography, CTG) for all viable gestations (≥24 weeks): assess fetal heart rate baseline, variability, accelerations, and decelerations; uterine contractions at ≥4 per hour may indicate abruption or preterm labour; CTG should continue for minimum 4 hours after minor trauma, extended to 24 hours if any abnormality is detected.
- 6Perform Kleihauer-Betke (KB) test in all Rh-negative pregnant trauma patients: KB identifies fetal erythrocytes in maternal circulation (fetomaternal haemorrhage); standard anti-D 300 mcg IM covers approximately 15 mL fetal red cells (or 30 mL fetal whole blood); larger fetomaternal haemorrhage requires additional anti-D doses calculated from KB result.
- 7Consider delivery (emergency caesarean section) if: the fetus is viable (≥24 weeks) and there is evidence of non-reassuring fetal status on CTG despite resuscitation; placental abruption with maternal or fetal deterioration; uterine rupture suspected; or maternal cardiac arrest — perimortem caesarean section at 4 minutes of CPR may be life-saving for both.
Failure to position correctly is a correctable, immediately life-threatening error in pregnant trauma patients beyond 20 weeks.
At 28 weeks, the gravid uterus compresses the IVC and aorta in the supine position — tilt immediately resolves the haemodynamic compromise before attributing hypotension to haemorrhage.
Placental abruption can be clinically silent initially — CTG detects uterine contractions and fetal distress before symptoms develop.
Even 'minor' trauma can cause placental abruption; 4 hours of CTG monitoring is the minimum for any pregnant trauma patient with a viable fetus.
Standard 300 mcg anti-D dose is adequate unless KB shows >15 mL fetal RBC transfer; if KB >15 mL fetal RBCs, give additional 300 mcg anti-D per 15 mL fetal RBCs.
Anti-D prevents Rh sensitisation which would cause haemolytic disease of the fetus/newborn in future pregnancies; the KB test quantifies the fetal haemorrhage and guides total anti-D dose needed.
Perimortem CS is performed to benefit BOTH mother (removes aortocaval compression, improving CPR effectiveness) and fetus.
Removal of the gravid uterus at 4 minutes of cardiac arrest improves cardiac output from CPR by relieving IVC compression; fetal survival is possible if delivered by 5 minutes; this decision must be made rapidly and not delayed by lack of consent.
Trauma teams use gestational age–position protocols to immediately apply left lateral tilt to all pregnant trauma activations ≥20 weeks, a simple intervention that may prevent haemodynamic instability., where accurate pregnancy trauma analysis through the Pregnancy Trauma supports evidence-based decision-making and quantitative rigor in professional workflows
Emergency nurses initiate CTG monitoring in pregnant trauma patients on arrival, allowing early detection of placental abruption-related fetal distress before clinical deterioration., where accurate pregnancy trauma analysis through the Pregnancy Trauma supports evidence-based decision-making and quantitative rigor in professional workflows
Obstetric teams perform Kleihauer-Betke testing and anti-D dosing calculations for all Rh-negative pregnant trauma patients to prevent haematological complications in future pregnancies., where accurate pregnancy trauma analysis through the Pregnancy Trauma supports evidence-based decision-making and quantitative rigor in professional workflows
Simulation programmes run pregnancy trauma scenarios to train multidisciplinary teams (trauma, obstetrics, neonatology, anaesthesia) in the coordinated management of perimortem caesarean section and maternal resuscitation., where accurate pregnancy trauma analysis through the Pregnancy Trauma supports evidence-based decision-making and quantitative rigor in professional workflows
Public health campaigns use data on seatbelt positioning in pregnancy to educate antenatal patients on correct belt placement, reducing uterine injury risk in motor vehicle collisions.
Domestic violence and intimate partner violence
Intimate partner violence (IPV) is the leading cause of trauma during pregnancy, accounting for 17–45% of cases depending on the population studied. Abdominal and uterine trauma from assault is common and may be concealed. All pregnant trauma presentations should include private, standardised IPV screening using validated tools (HITS, WAST) with access to social work, domestic violence advocacy, and safe discharge planning. Mandatory reporting requirements vary by jurisdiction.
Burns in pregnancy
Burns >40% total body surface area (TBSA) are associated with maternal mortality >50% and near-universal fetal loss. Fluid resuscitation follows standard Parkland formula; fetal CTG monitoring should be initiated early; intubation thresholds are lower due to accelerated airway oedema. Premature labour is common after severe burns. Delivery should be considered if fetal distress occurs and the fetus is viable.
Penetrating abdominal trauma
The gravid uterus acts as a shield for maternal viscera in abdominal penetrating trauma — maternal visceral injury rates are paradoxically lower in pregnant patients with gunshot wounds. However, uterine, fetal, and amniotic fluid injury rates are high. Fetal mortality from penetrating uterine trauma is 40–70%. Surgical exploration is indicated for haemodynamic instability, peritoneal signs, or concern for uterine penetration.
Fetal radiation exposure from trauma imaging
The lifetime risk of childhood cancer from fetal radiation increases by approximately 0.006% per mGy above baseline. At the doses delivered by CT trauma surveys (25–50 mGy), the absolute risk increase is <0.3% above a baseline childhood cancer risk of approximately 0.3%. Lead shielding of the pelvis during non-pelvic CT is generally not recommended as it may cause artefact and does not substantially reduce scattered radiation to the fetus.
| Gestational Age | Uterine Position | Key Risk | Primary Action |
|---|---|---|---|
| <12 weeks | Within bony pelvis | Early pregnancy loss; ectopic rupture | Confirm intrauterine pregnancy; BHCG |
| 12–20 weeks | Pubic symphysis to umbilicus | Uterine injury; early placental abruption | FAST exam; fetal heart tones |
| 20–24 weeks | Umbilicus; IVC compression begins | Aortocaval syndrome; pre-viable fetus | Left lateral tilt; viability counselling |
| 24–36 weeks | Umbilicus to xiphoid | Abruption; preterm labour; IVC compression | CTG ≥4h; tilt; KB test; anti-D if Rh− |
| >36 weeks | Near xiphoid | Uterine rupture; IVC compression maximal | Urgent obstetric review; perimortem CS if arrest |
At what gestational age does the uterus become susceptible to traumatic injury?
Before 12 weeks, the uterus is entirely within the bony pelvis and is protected from most abdominal trauma. From 12 weeks, it rises above the pubic symphysis and becomes increasingly vulnerable to blunt abdominal trauma. By 20–24 weeks, the fundus reaches the umbilicus and the uterus is a large intra-abdominal organ directly at risk from steering wheel impact, seatbelt compression, and penetrating wounds.
What is placental abruption and how does trauma cause it?
Placental abruption is premature separation of the placenta from the uterine wall, causing maternal haemorrhage and interrupting fetal oxygen supply. Trauma can cause abruption through a shearing mechanism — when a sudden deceleration or direct blow causes the relatively rigid placenta to separate from the elastic uterine wall. Abruption can be complete (total separation) or partial and may be concealed (no external bleeding) or revealed. Fetal compromise may precede maternal haemodynamic instability.
Is it safe to use CT scanning in pregnant trauma patients?
Yes. CT scanning is safe and should not be withheld from pregnant trauma patients when clinically indicated. The radiation dose from a standard trauma CT scan (CT head/chest/abdomen/pelvis) is approximately 25–50 mGy, well below the threshold for deterministic fetal harm (>100 mGy). Maternal death or missed injury is a far greater risk to the fetus than CT radiation — imaging should be obtained based on clinical indication without delay.
Should seatbelts be worn during pregnancy?
Absolutely yes. Properly worn seatbelts (lap belt below the uterus, across the pelvis; shoulder belt across the chest, between the breasts, not over the uterus) significantly reduce maternal and fetal mortality from MVC. Paradoxically, improperly worn seatbelts (lap belt over the uterus) can cause uterine rupture in a collision. Safety education about correct seatbelt positioning in pregnancy is an important prenatal counselling topic.
What is the Kleihauer-Betke test?
The Kleihauer-Betke (KB) acid elution test detects fetal haemoglobin (HbF) in maternal blood by treating a blood smear with acid — adult haemoglobin is eluted, leaving ghosted cells, while fetal cells with HbF stain darkly. The percentage of fetal cells indicates the volume of fetomaternal haemorrhage and guides anti-D immunoglobulin dosing. Flow cytometry is an alternative and more quantitative method.
What haemodynamic parameters are normal in pregnancy?
Normal pregnancy physiology: HR +10–15 bpm above pre-pregnancy baseline (normal 85–100 bpm); BP 10–15 mmHg lower (normal 100/60–110/70 in mid-pregnancy); cardiac output increased 30–50% by term; haemoglobin 10–12 g/dL (physiological dilutional anaemia); plasma volume increased 40–50%; reduced SVR; and mildly elevated WBC (up to 15 × 10⁹/L). These parameters can mask early signs of haemorrhage — a pregnant patient may lose 30% of blood volume before vital signs deteriorate.
Can CPR be performed normally on a pregnant patient?
Yes, but with modifications. Standard chest compression technique and rate apply. The key modification is maintaining left lateral uterine displacement throughout CPR (manual or wedge) to relieve aortocaval compression. Defibrillation is performed normally — the fetus is not at risk from defibrillation shocks. If ROSC is not achieved by 4 minutes, perimortem caesarean section should be performed immediately to improve CPR effectiveness and fetal survival.
What are indications for emergency caesarean section after trauma?
Emergency CS is indicated for: non-reassuring fetal CTG not responding to resuscitation in a viable fetus; placental abruption with fetal compromise; uterine rupture; maternal cardiac arrest at ≥20 weeks gestation (perimortem CS); traumatic delivery with haemorrhagic shock; or DIC from abruption threatening maternal life. The decision must be made in conjunction with obstetrics and neonatology.
プロのヒント
In pregnant trauma patients, always remember you are treating two patients simultaneously. The fetus is uniquely vulnerable to placental abruption even from seemingly minor trauma, and clinical signs lag behind physiological compromise. Apply left lateral tilt, initiate CTG for any viable fetus, run a Kleihauer-Betke test in all Rh-negative patients, and involve obstetrics early — these four steps save the greatest number of fetal lives.
ご存知でしたか？
The first documented perimortem caesarean section was reportedly performed by Jacob Nufer, a pig gelder from Switzerland, on his wife in 1500 after an obstructed labour — and both mother and child reportedly survived. Today, perimortem CS is a standard component of advanced life support protocols for pregnant patients in cardiac arrest, with survival rates for both mother and baby improving dramatically when performed within 5 minutes of arrest.
参考文献
- ›ATLS — Advanced Trauma Life Support, 10th Edition — Trauma in Pregnancy
- ›ACOG Practice Bulletin No. 251 — Trauma in Pregnancy (2022)
- ›Battaloglu E, Porter K — Management of pregnancy and obstetric complications in prehospital trauma care (Emerg Med J, 2017)
- ›Jain V et al. — Guidelines for the management of a pregnant trauma patient (SOGC, 2015)
- ›Einav S et al. — Maternal cardiac arrest and perimortem caesarean delivery: evidence or expert-based guidance? (Resuscitation, 2012)