Obstetrics 9: Trauma in Pregnancy Portal
Major trauma affects up to 8% of pregnant patients and is the leading cause of maternal death due to non-obstetric etiologies. Physiologic changes during pregnancy result in an altered response to trauma that may affect the clinician’s ability to diagnose traumatic injury accurately. Several important points are outlined below.
Plasma volume increases by 40% to 50%, which imparts a natural protection against blood loss; thus, moderate maternal blood loss in trauma may be well tolerated. Loss of 2000 mLs of blood may not be clinically apparent.
Maternal blood pressure drops by 20% in the second trimester and returns to baseline at the end of the third trimester.
Oxygen consumption by the pregnant patient is higher due to increased demand, higher minute ventilation and lower tidal volume due to a gravid fetus impinging on the diaphragm. Oxygen saturations drop rapidly.
Intubating a pregnant patient is 5 to 8 times more difficult on the term mother due to airway edema and high oxygen requirements. Careful airway decision-making is required.
Different mechanisms of maternal injury occur in blunt trauma due to the gravid uterus and increased uterine vascularity. The uterus becomes a lower abdominal organ by the 12th week of gestation and blood flow is increased markedly throughout pregnancy. There may be appreciable hemorrhage due to uterine injury or pelvic trauma. Spleen, liver and retroperitoneal organs are injured in up to 25% of blunt trauma injuries.
A hemodynamic effect of pregnancy is hypotension induced by aortocaval compression by the gravid uterus. Cardiac output can drop 25%. Use a right hip wedge, manual displacement of the uterus or lateral tilt of the immobilized, boarded pregnant trauma patient.
Up to 40% of severe blunt abdominal trauma is associated with placenta abruption resulting from a rather elastic uterus with a fixed placenta. Shearing forces strip the placenta from the uterus. Instruct pregnant patients on the correct placement of seatbelts in motor vehicles. The pregnant patient should sit as far back from airbags as possible.
Even minor trauma can result in fetal mortality of 2% to 5%. Fetal monitor the pregnant patient over 24 weeks gestation for at least 4 hours. They may be safely discharged only after a normal physical exam and no contractions or vaginal bleeding.
Evaluate the pregnant patient like any other trauma patient. If the mother doesn’t do well, the baby doesn’t do well. Standard x-rays are not contraindicated; this includes CT scanning of the abdomen and pelvis.
Trauma in Pregnancy
| Time | Steps | Evaluation/Intervention |
|
0 – 5 min |
Arrival at ED |
|
| 5 – 10 min | Initial Survey | Airway assessment – intubation may be difficult so have a secondary airway plan.
Breathing assessment – 100% oxygen. Mother and fetus tolerate hypoxemia poorly. Semi-supine position minimizes fundal pressure on the diaphragm. Circulation assessment – 2-large bore IVs. Replace volume & control active bleeding. Disability assessment – check pupils. Exposure – Remove all clothing and keep patient warm. Note environmental exposures such as cold, smoke, chemicals, etc. |
| 10 – 30 min | Secondary Survey | Head-to-toe physical examination with frequent ABCD re-evaluation Obtain SAMPLE history. Apply BP, Cardiac, and SaO2 monitor. Pain Management Obtain obstetric history – Gravida, Parity, LMP, gestational age, EDC, previous U/S – placental location, pregnancy complications, vaginal bleeding or ruptured membranes. Obtain a pregnancy test on all female trauma patients of childbearing age. Obtain a blood type on all pregnant trauma patients. Women who are RH negative will require Rhogam. Use the Kleihauer Betke test to determine the amount of Rhogam needed to prevent sensitization. |
| 30 min | Ongoing Care | Stabilize mother then move to fetal evaluation Fundal height – after 20 weeks, cm distance from symphysis to fundus equals weeks gestation Bedside ultrasound – fetal viability, number, position of fetus, fetal heart rate, placental location, amniotic fluid index. Preliminary impression/Working diagnosis Triage decision – If gestational age is less than 36 weeks anticipate neonatal resuscitation and NICU may be needed. Consider transport unless imminent delivery is likely. Consider phone consultation with appropriate specialists. Follow diagnostic and treatment portals – Trauma, Emergency C-section, Imminent Delivery, etc. |
References
- Van Hook, James, Clinical Ob and Gyn, June 2002.
- Gabbe, Steven, Obstetrics, Normal and Problem Pregnancies, 4th Edition, 2002.