Trauma in Pregnancy

Incidence

6% to 7%; “at no other time in a woman’s adult life is she more at risk for trauma than the third trimester of pregnancy”

Motor vehicle accidents: number one cause of trauma during pregnancy; incidence distributed equally throughout pregnancy

Falls: second most common cause of trauma during pregnancy; most occur during 20 to 30 wk gestation; patients have altered center of gravity, respiratory alkalosis (causing lightheadedness and dizziness), and laxity of pelvic ligaments, predisposing them to falls

Domestic abuse: third leading cause of trauma during pregnancy; tends to be associated with significant fetal injury because trauma almost always directed toward abdomen and uterus

Trauma: leading cause of nonobstetric death in women and leading cause of death in women of childbearing age; maternal survival leading predictor of fetal survival

Normal changes during pregnancy all systems involved; cardiac output increases by almost 40% by 10 wk gestation and remains elevated until term; heart rate increases 10 to 15 beats/min by term (80-95 beats/min normal during pregnancy); systemic vascular resistance decreases; widened pulse pressure (due to larger drop in diastolic than in systolic blood pressure), low blood pressure

Supine hypotensive syndrome: gravid uterus resting on inferior vena cava decreases venous return, can decrease cardiac output by up to 30%; placing patient in left lateral decubitus position increases blood pressure; if changing patient’s position contraindicated, manually displace uterus to left

Blood volume: increases by 50% by 28 wk gestation; red blood cell mass increases 18% to 30%, resulting in dilutional physiologic anemia of pregnancy (obtaining previous medical records helpful); hemoglobin and hematocrit (H&H) lowest at 30 to 34 wk; pregnant women can lose 10% to 20% of blood volume acutely without change in vital signs, 33% if blood loss gradual (fetus probably will not survive; increased blood volume needed to feed fetus)

Leukocytosis of pregnancy: hormonally mediated; average white blood cell count 12,000 to 18,000/mm3 (almost all polymorphonuclear leukocytes, making it difficult to assess infection), reaching up to 25,000/mm3 during labor

Hypercoagulable state: prevents or decreases effects of maternal hemorrhage; predisposes patients to thromboembolic disease (highest risk in third trimester and first month postpartum); prothrombin time (PT) and partial thromboplastin time (PTT) shortened; fibrinogen almost doubles (normal reading probably early indicator of disseminated intravascular coagulation [DIC])

Pulmonary changes: minute ventilation increases up to 40%; normal PCO 2 of woman in third trimester approximately 30 mm Hg (bagging patient to 40 mm Hg will cause fetal and maternal acidosis and fetal distress)

Diaphragm: abdominal contents pushed cephalad; decreased functional residual capacity; chest tube should be placed 1 to 2 intercostal spaces higher than usual; diaphragm can rise as much as 4 cm; bowel motility and gastric emptying decreased (general relaxation of gut); decreased lower esophageal sphincter pressure (effect of progesterone; causes reflux); increased gastric acid production; empty stomach using nasogastric (NG) tube to decrease risk for aspiration; alkaline phosphatase markedly increased (placental origin); uterus largest intra-abdominal organ by third trimester (not problem in blunt trauma but significant injuries possible with penetrating trauma); due to stretched peritoneum and abdominal muscles, patients often show minimum signs of peritoneal irritation despite as much as liter of blood in abdomen

Genitourinary system: uterus can increase to 1200 g by third trimester (normally 60-80 g); blood flow increases from 60 mL/min to 600 mL/min (every 10 min, entire circulating blood volume of mother goes through uterus; patient can exsanguinate in approximately 10 min); always admit pregnant patients with pyelonephritis because natural hydroureter and hydronephrosis increase risk of seeding blood stream; glomerular filtration rate increases by 50%, blood urea nitrogen (BUN) and creatinine drop by approximately 50%; in pregnant trauma victim, borderline or high creatinine indicates significant renal injury until proven otherwise

History last menstrual period (always obtain pregnancy test on every woman of childbearing age in trauma); estimate length of pregnancy; if fetus not viable, direct all resuscitative measures to mother; if fetus viable, must alter treatment; patients with history of cesarean delivery at increased risk for uterine rupture

Physical examination estimate fundal height (if greater than or equal to 2 finger breadths above umbilicus, fetus probably viable); look for uterine tenderness, uterine contour, and contractions (signs of abruption or uterine rupture); check for fetal heart rate by stethoscope (by 18-20 wk), Doppler imaging (10-14 wk), or transabdominal or transvaginal ultrasonography (6-7 wk); normal fetal heart rate 120 to 160 beats/min (if outside this range, fetal distress until proven otherwise); fetal hemodynamics most sensitive indicator of maternal hemodynamics

Pelvic examination contraindicated in patients in third trimester with vaginal bleeding; if no contraindications, perform sterile speculum examination looking for perineal and vaginal lacerations and urethral injury; examine vagina for open os, light urethral dilation, crowning; measure pH (alkaline pH suggests ruptured membranes; ferning in fluid sample from posterior fornix more specific for amniotic fluid)

Blood obtain blood type and screen on all pregnant patients beyond 12 wk gestation; complete blood count (CBC) and H&H low

Kleihauer-Betke test no longer recommended for all pregnant trauma patients; identifies presence and estimates gross amount of fetal red blood cells in maternal circulation (no relation to severity of injury); obtain only on Rh-negative mothers to quantify how much RhoGAM (RhO [D] immune globulin) to give; 300 µg of RhoGAM protects mother from 30 mL of fetal-maternal hemorrhage; Kleihauer-Betke test can help determine whether more RhoGAM needed)

Coagulopathy studies if mother has significant trauma, draw baseline blood sample to determine whether she is going into DIC (clue to abruption)

Imaging studies “if the woman was not pregnant and she needed the x-rays, get the x-rays”; “the risk of missing the injury is much, much greater than any risk of radiation exposure to the fetus”; no significant risk of increased teratogenic effect if fetus exposed to <10>15 rads; fetus most vulnerable in weeks 2 to 7; unlikely x-rays cause harm to fetus at >20 wk gestation; shield pelvis and limit number of views if possible (eg, to clear C-spine, use only lateral, anteroposterior, and odontoid views, omit oblique view); routine pelvic films no longer indicated in trauma patients

Ultrasonography: key to evaluation; determine fetal heart rate (good indicator of how fetus and mother are doing); determine fetal age; only 50% sensitive for detecting abruption

Abdominal ultrasonography: perform focused assessment with sonography for trauma (FAST) examination; should not have fluid in cul de sac or between liver and peritoneum; if FAST examination positive and patient hemodynamically unstable, send patient to operating room (OR); if FAST positive and patient stable, send patient for computed tomography (CT); if FAST negative, observe or scan again in 30 min

Cranial CT: be sure to shield fetus

CT of abdomen and pelvis: causes more radiation exposure; reduce radiation by performing 3-cm cuts instead of 1-cm cuts (some sensitivity lost but not enough to significantly alter interpretation of examination); can see uterine rupture and abruption; not good for detecting fetal injury

Angiography: performed for therapeutic as well as diagnostic reasons; contrast not contraindicated in pregnancy

Diagnostic peritoneal lavage (DPL): indicated only when CT and ultrasonography not available; use supraumbilical open approach; does not detect retroperitoneal injuries

Fetal monitoring: if fetus <23>23 wk, use continuous cardiotocographic monitoring

Cardiotocographic monitoring: measures fetal heart rate and uterine contractions; best test for abruption (100% sensitive); have low threshold for performing this test (reassures mother); if no uterine contractions in 2 hr, can send patient home safely; if even one contraction, monitor for another 2 hr

Management administer high-flow 100% O2 (benefits fetus; fetus has O2 -hemoglobin dissociation curve different from that of mother); if fetus >20 wk gestation, place mother in left lateral decubitus position if not contraindicated; if contraindications present, displace uterus to left; no role for military antishock trousers (MAST; inappropriate and may be harmful); cardiac monitor for mother, intermittent monitoring for fetus if <23>23 wk

Fluids: 2 large-bore intravenous (IV) lines (use upper extremities if possible); restoring circulating volume initial goal; Ringer’s lactate preferred over normal saline; give blood transfusion early (fetus will die if physician waits for signs of shock)

NG tube: empty stomach; pregnant patients at increased risk for aspiration

Vaccinations: tetanus toxoid and tetanus immune globulin safe in pregnancy; indicated if vaccinations not up-to-date

Medications: RhoGAM for Rh-negative mothers (give if >12 wk gestation); safe to give penicillin, Timentin (ticarcillin and clavulanate), Augmentin (amoxicillin and potassium clavulanate), cephalosporins, erythromycin, clindamycin, nitrofurantoin; stay away from tetracyclines (can cause teeth and bone problems in fetus, maternal toxicity), fluoroquinolones (can cause cartilage problems and arthropathy in fetus), sulfa agents (in third trimester; cause kernicterus), trimethoprim (folate inhibitor), chloramphenicol; Tylenol (acetaminophen) safe; make sure patient not taking aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs; can cause premature closure of ductus arteriosus); narcotics safe in pregnancy, but avoid codeine in first trimester (associated with increased incidence of cleft palate); can give Demerol (meperidine) or morphine

Abruption 1% to 5% incidence in minor trauma, 20% to 50% in major trauma; second leading cause of death in fetuses (death of mother most common cause); patients classically present with vaginal bleeding and abdominal pain; not all have classic presentation (bleeding may be hidden behind placenta; pain may be minimal or patient may have distracting injuries); consider abruption if mother has hypotension and no apparent sign of blood loss (uterus can hold 2 L of blood), fundal height much higher than expected for dates, or uterus expanding; cardiotocographic monitoring best test; increasing use of D-dimer test to detect early DIC; fetus with <25%>50% separation unlikely to survive unless delivered immediately; obstetric specialist must make decision on what to do with abruptions of 25% to 50%; do not let absence of vaginal bleeding prevent diagnosis of abruption

Uterine rupture rare (incidence <1%);>

Traumatic cardiac arrest
if fetus <23>23 wk gestation, obtain obstetric consult and consider early resuscitative thoracotomy; do not cross-clamp aorta.

Source : http://emcrit.org/030-064/031-trauma.pregnant.htm