Evaluation and Management of Trauma in Pregnancy

Trauma involves approximately 6%–7% of all pregnancies.

Trauma results in maternal and fetal injuries.

Causes

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  Motor vehicle collision (MVC)

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    Most common cause in the United States

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    Unrestrained drivers have a higher risk of fetal and maternal injuries.

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    Use of seat belt in pregnancy

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      Shoulder restraints in conjunction with a lap belt reduce the incidence of direct and indirect fetal injuries.

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      Shoulder restraints should be placed between the breasts and to the side of the abdomen.

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      Shoulder belts alone without lap belts are associated with risk of uterine rupture or abruptio placentae (placental abruption). Lap belt should be placed in the lower abdomen touching the thighs and hip bones.

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      High placement of a lap belt (over the uterus) may cause uterine rupture due to transmission of direct force to the uterus.

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  Assault

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    May be due to blunt or penetrating trauma to the abdomen

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  Falls

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    More common in the latter half of pregnancy

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    Increase in lumbar lordosis moves the center of gravity forward, contributing to an increased incidence of falls.

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  Penetrating injury

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    Gunshot wounds (GSWs) and stab wounds

Maternal injury pattern:

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  Bowel injury in penetrating trauma

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    Intestine is pushed up and shielded by the uterus after midpregnancy.

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    Lower incidence of bowel injuries in penetrating abdominal trauma

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    Higher incidence of bowel injuries in thoracoabdominal penetrating trauma

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  Solid organ injury

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    Patterns of blunt abdominal injury remain the same as in nonpregnant patients because the location of these organs do not change in pregnancy.

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  Urinary bladder

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    Urinary bladder is displaced anteriorly and superiorly by the gravid uterus after 12 weeks of gestation, making it an extrapelvic organ with increased risk of injury.

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    High risk of retroperitoneal bleeding in patients with pelvic fracture due to engorgement of the pelvic vessels surrounding the gravid uterus.

Fetal injury pattern:

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  Direct fetal injury

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    Commonly due to direct blunt abdominal wall trauma

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    Abdominal wall, uterine myometrium, and amniotic fluid may act as protective barriers.

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  Indirect injury may be due to:

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    rapid compression.

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    deceleration resulting in shearing force.

Maternal evaluation and resuscitation are the priorities.

Maternal resuscitation is important to prevent fetal hypoxia and death.

Unstable patients should be identified and managed emergently.

Evaluation of the fetus should be performed after maternal assessment and resuscitation.

Evaluation follows the same algorithm as in nonpregnant patients:

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  Airway

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  Cervical spine protection

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  Breathing

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  Circulation

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  Disability

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  Exposure

Airway

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  Fetus is very sensitive to maternal hypoxia.

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  Pregnant patients have a high-risk of hypoxia due to the following:

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    Decrease in functional residual capacity

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    Decrease in total lung capacity

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    Reduced respiratory compliance

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    Decrease in oxygen reserve

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    Marked increase (15%–20%) in basal oxygen consumption

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    Normal PaO2: <60 mm Hg

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    Normal oxygen saturation: <95%

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  High risk of aspiration due to poor gastric emptying and relaxed lower esophageal sphincter. Early nasogastric tube placement is recommended.

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  Special considerations during intubation of pregnant patients

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    Risk of bleeding due to mucosal engorgement of the nasal passage, oropharynx, larynx, and trachea

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    To avoid intubation trauma, during intubation, consider an endotracheal tube (ETT) 0.5–1 mm smaller than for nonpregnant patient to avoid intubation- related trauma.

Spine immobilization

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  Spine immobilization technique:

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    Cervical collar for C-spine immobilization

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    Back board for spine immobilization

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      Patients with >20 weeks of gestation should be immobilized in the left lateral decubitus position with 30-degree to 50-degree tilt to avoid pressure on the inferior vena cava (IVC).

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      Pressure on the IVC can cause supine hypotensive syndrome.

Breathing and ventilation

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  Adequate maternal breathing is essential to maintain fetal oxygenation.

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  Goal is to maintain maternal oxygen saturation >95% and PCO2 ≤30 mm Hg.

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  Ventilatory parameters require adjustment based on the following physiological changes in pregnancy:

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    Increase in tidal volume

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    Increase in minute ventilation by 50%

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    Decrease in residual volume due to diaphragmatic elevation

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    Increased airway resistance

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    Reduced respiratory compensation for metabolic acidosis

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    Baseline respiratory alkalosis due to hyperventilation

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    Normal blood gases in pregnancy

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      pH range: 7.40–7.45

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      Bicarbonate range: 17–22 mEq/L

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      Base excess range: 3–4 mEq/L

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  Chest tube placement

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    Chest tube should be placed 1–2 intercostals higher than usual due to displacement of the diaphragm during pregnancy.

Circulation and control of bleeding

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  Effective maternal circulatory volume is essential for fetal placental circulation.

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  Hemorrhagic shock results in uterine vasoconstriction causing fetal hypoxia.

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  High risk of fetal distress with:

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    50% decrease in maternal hematocrit.

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    20% decrease in maternal mean blood pressure.

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  Causes of hemorrhagic shock

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    External or internal injuries

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    Concealed uterine bleeding

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  Clinical manifestations of hemorrhagic shock are not reliable:

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    Patients may remain hemodynamically stable despite significant blood loss due to the following physiological changes in pregnancy:

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      Increase in heart rate 10–15 beats/min

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      Increase in blood volume by 45%

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      Increase in red cell mass by 25%

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      Decrease in systolic blood pressure (SBP) by 2–4 mm Hg and diastolic blood pressure (DBP) by 5–15 mm Hg in the second trimester, and it returns to normal in the third trimester.

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      Increase in cardiac output by 30%–45%

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  Resuscitation of hemorrhagic shock

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    High risk of pulmonary edema from crystalloid infusion and blood transfusion due to decrease in colloid osmotic pressure in pregnancy

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    Vasopressors in pregnancy

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      Norepinephrine and epinephrine (Adrenalin) are not recommended due to the risk of fetal hypoxia from uteroplacental vasoconstriction.

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      Ephedrine

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      Safe in pregnancy

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      Increases alpha- and beta-adrenergic activities

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      Mephentermine

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      Safe in pregnancy

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      No effect on uterine perfusion

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      Inotropic effect on the myocardium

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  Supine hypotensive syndrome

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    Compression on the IVC by the gravid uterus after >20 weeks of pregnancy in supine position can result in reduced venous return causing reduced cardiac output and hypotension.

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    Pressure on the vena cava can be prevented by placement of the patient in the left lateral decubitus position with 15-degree to 30-degree tilt.

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  Blood transfusion

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    O-negative blood is recommended in Rh-negative patients to avoid Rh sensitization.

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  Patients with preeclampsia

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    Blood pressure monitoring is not a reliable sign.

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    May be associated with reduced intravascular volume

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    Risk of pulmonary edema from crystalloid infusion due to increased capillary permeability

Disability (neurological status)

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  Differential diagnosis in pregnant patients with head injury

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    Postural hypotension with dizziness due to vasodilation in pregnancy

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    Eclampsia

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      Grand mal seizures

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      Loss of consciousness

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      Hyperreflexia

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      Headache

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      Vision changes

Evaluation follows the same algorithm as in nonpregnant patients.

Detailed obstetric history is important:

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  Last menstrual period (LMP)

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  Previous pregnancies

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    Miscarriages

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    Premature deliveries

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    Abortions

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    History of delivery including complications

Abdominal examination

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  Stretching of the abdomen and increase in intraabdominal pressure results in a desensitivity to peritoneal irritation.

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  Fluid or blood in the peritoneal cavity may not show signs of peritoneal irritation as tenderness, rebound tenderness, or guarding.

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  Irregular abdominal examination during palpation due to palpable fetal parts in uterine rupture.

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  Assessment of the uterus

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    Height of the fundus

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    Shape of the uterus

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    Tone and tenderness

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    Uterine tenderness is an important sign of placental abruption.

Pelvic examination

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  Pregnancy >24 weeks gestation with vaginal bleeding

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    May be due to disruption of the placenta.

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    Ultrasound should be performed first to exclude placenta previa.

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    Vaginal examination with speculum should be performed to assess the following:

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      Cervical dilatation

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      Presentation of the fetus

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      Amniotic fluid

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      Vaginal or cervical lacerations

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      Expulsion of gestational tissue

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      Ruptured membrane

Interpretation of laboratory results

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  Anemia is normal. It is caused by an increase in plasma volume relative to the increase in red cell mass.

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  Leukocytosis is a normal. It may not be an indicator of infection.

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  Blood urea nitrogen (BUN) and creatinine decrease by half of the prepregnancy level. Normal BUN and creatinine is abnormal in normal pregnancy.

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  Normally calcium and magnesium levels are low in pregnancy.

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  Glycosuria is often physiological during pregnancy.

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  Fibrinogen level

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    Normally elevated in pregnancy

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    Hypofibrinogenemia (<2 g/L) may be due to disseminated intravascular coagulation (DIC) from placental abruption.

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  Alkaline phosphatase

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    It is secreted by the placenta.

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    Elevated levels, even twice the upper limit for nonpregnant patients, may be normal in pregnancy.

Imaging for maternal trauma evaluation

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  Radiological evaluation of the mother is the priority despite the risk to the fetus of radiation exposure (Eastern Association for the Surgery of Trauma Guidelines (EAST], 2010).

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  The fetus should be protected with a shield whenever possible.

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  Repeat imaging should be avoided.

Ultrasound

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  No risk of radiation exposure to the fetus

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  Intraperitoneal blood may be detected with Focused Assessment with Sonography in Trauma (FAST).

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  FAST exam becomes less accurate with increased gestational age because the gravid uterus occupies the abdominal cavity.

Plain films

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  Low radiation exposure to the fetus

CT scan

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  Recommended if there is significant concern for intraabdominal injury

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  Associated with fetal radiation exposure

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  Usually radiation exposure <5 rad (50 mGy) does not have any fetal adverse effect.

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  Radiation exposure

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    CT head: <0.05 rad

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    CT chest: <0.1 rad

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    CT abdomen/pelvis: <2.6 rad

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  Effects of radiation

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    Increased risk of miscarriage: Exposure before 5 weeks of gestation

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    Teratogenic effect: Exposure during the period of organogenesis (5–10 weeks of gestation)

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    Growth retardation

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    Central nervous system (CNS) effects: Exposure even after 10 weeks of gestation

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    Malignancy: Exposure even after 25 weeks of gestation

Magnetic resonance imaging (MRI)

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  No adverse fetal effects

Diagnostic peritoneal lavage (DPL) in pregnancy

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  May be used for the rapid detection of intraabdominal injury

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  Sensitivity: 96%–100%

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  Does not provide information about specific organ injury

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  Open technique with catheter placement above the umbilicus is recommended to minimize injury to the gravid uterus.

Direct injury

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  Commonly due to direct blunt abdominal wall trauma

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  Abdominal wall, uterine myometrium, and amniotic fluid may act as protective barriers.

Indirect injury

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  Rapid compression

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  Deceleration resulting in shearing force

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  Fetal hypoxia

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    Maternal hypovolemic shock leading to fetal hypoxia

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    Maternal hypoxia

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  Fetomaternal hemorrhage (FMH)

Risk of fetal injury increases with gestational age:

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  Less risk of injury in the first trimester due to thick-walled intrapelvic uterus

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  High risk of injury in second and third trimester due to:

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    thin-walled intraabdominal uterus.

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    thinning of the maternal abdominal wall.

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    direct contact of the uterus with the abdominal wall.

Preterm delivery

Spontaneous abortion (miscarriage)

Direct fetal injury

Placental abruption

Uterine rupture

Uteroplacental injury

Rh isoimmunization