Management of the pregnant trauma patient

Trauma in 5% of pregnancy, of which greater than 50% are MVAs, and of these 82% of fetal deaths occur during the accident.
*MVA 1/2, Falls 1/5, Assaults 1/5, Burns 1/100
Life threatening trauma results in 50% fetal loss rate.
The most common cause of fetal death after blunt trauma is abruption.
Anterior abdominal penetrating trauma will (unless proven otherwise) injure the fetus >20/40 weeks gestation.
Peri-mortem caesarian has poor prognosis.
Note there are preventive (non-medical) measures which exist are effective when followed. (physical abuse, alcohol, seat-belts)

Principles (on top of basic trauma principles)
Changes in maternal physiology.
Radiation/medication risks greater in early pregnancy.
Fetus viable after 23-24 weeks.
Two-patients: good management of mother is good for fetus usually.
Fetus hates hypoxaemia and hypovolaemia.
Remember the signs of fetal distress (tachycardia, decreased variability, decelerations)

Multi-disciplinarian approach
Trauma surgeon, emergency physician, technicians, obstetricians, neonatologist, many specialist nursing staff.

Prehospital issues
History
Beware of the distended abdomen. Also avoid direct pressure on abdomen (e.g. MAST)
Lateral decubitus
Transfusion with O negative

Emergency care issues (on top of ATLS principles)
All investigations (including radiology) and interventions for the mother necessary should be performed (e.g. DPL)
Estimation of gestation from fundal height; any fetus >23 wks should prompt immediate monitoring, which includes tocography and FHS. (umbilicus 20wks) NB 25% of trauma after 2240 wks gestation is complicated by premature labour
Secondary survey includes rectal and vaginal exam (cervical effacement, dilation, blood/amniotic fluid, etc), except in 3rd trim, where there's need to exclude placenta praevia
FAST is useful (intraabdominal bleed sensitivity 83%)
Kleihauer-Betke test, if positive this is relevant to Rhesus negative mothers.
ABG respiratory alkalosis, dilutional anaemia

Intensive care issues
Think pregnancy conditions and post-partum conditions.
DVT, PE prophylaxis

Blunt Trauma
Not as problematic in <13/40 gestation, unless there is pelvic fracture with 25% chance of fetal loss. Placenta is never elastic, even if myometrium is after 20wks: abruptions usually suspected with uterine activity. Think coagulopathy/DIC and fetal loss. Penetrating Trauma after 20wks uterus usually protective. Tetanus toxoid should be given. C-section C-section post trauma for >25/40wks gestation has 45% survival and 72% maternal survival rate.
Peri-mortem c-section is often futile. Consider after 4minutes of CPR to help fetal survival and aid maternal resuscitation.

Reference:
Kenneth L M, Goetzl, L. Trauma in pregnancy. Critical Care Medicine 2005 Vol. 33, No. 10 (Suppl.)

Thnks to William Ng for contributing this wonderful article.