II. Epidemiology
III. Precautions: Pearls
- Assume pregnancy in all females of reproductive age
- Seemingly minor injuries (e.g. fall from standing) can have major maternal and fetal complications
- Minor Trauma is responsible for 60-70% of fetal losses
- Fetal Monitoring recommendations are the same for both minor and major Trauma
- Premature labor may occur in 11-25% of patients with minor Trauma
-
Hemorrhagic Shock can be masked until cardiovascular collapse and Cardiac Arrest
- Pregnant women have 20% Cardiac Output reserve allocated to uterine Blood Flow
- Blood is shunted from the Uterus and fetus in obstetric Trauma with Hemorrhage
- Peritoneal cavity increases in size as Uterus expands with decreased overall innervation
- Signs of shock may be delayed until 30% of Blood Volume is lost
- Respiratory depression, Hypoxia and airway risks
- Higher CNS sensitivity to Opioids in pregnancy (reduced Opioid dose needed)
- Adequate analgesia results in less risk of Preterm Labor (lower Catecholamine surge)
- Higher airway compromise and Hypoxia risk in pregnancy (pharynx/Larynx edema, less functional reserve)
- Increased aspiration risk (due to decreased lower esophageal sphincter pressure, decreased gastric emptying)
-
Hypotension and uteroplacental insufficiency risks
- Aortocaval compression with reduced fetal Blood Flow when supine, esp. >20 weeks (position in decubitus)
- Hypotension (esp. if >25-30% drop in Blood Pressure)
- Hyperventilation and Metabolic Alkalosis
IV. Pathophysiology
- Pregnancy related physiologic changes
- Heart Rate increases 15-20 beats/minute
- Systolic and Diastolic Blood Pressure falls 15-20 mmHg in first and second trimester, normal in third trimester
- Peripheral Vascular Resistance decreases
- Blood Volume increases 30-50% in pregnancy
- Oxygen Consumption increases 25% in pregnancy
- Respiratory Rate increases 40-50% in pregnancy
- Hypercoagulable state
- Fibrinogen and Coagulation Factors increase in pregnancy
- Pregnancy related anatomic changes (especially third trimester)
- Diaphragm elevates
- Total Lung Capacity decreases, but Tidal Volume increases significantly (decreased Residual Volume)
- Delayed Gastric Emptying and decreased lower esophageal sphincter tone
- Uterine growth (especially third trimester)
- Uterus expands outside the protective Bony Pelvis
- Vena cava compression in supine patient from gravid Uterus decreases Preload
- Uterine wall thins as pregnancy progresses
- Placenta is susceptible to external forces that may provoke Placental Abruption
- Diaphragm elevates
V. Causes
- Motor Vehicle Accident (42-48%)
- Falls (25-34%)
- Most common in third trimester
- Direct Blunt Abdominal Trauma (18%)
-
Intimate Partner Violence (17%)
- Gunshot Wounds
- Stabbings
- Suicide (3%)
VI. History
- See Trauma History
- Pregnancy history
- Gestational age
- Multiple Gestation
- Rh Status
- Prior pregnancies (including prior Cesarean Section)
- Prenatal Care and prior Ultrasounds
- Pregnancy complications
- Mechanism of injury
- Possible Intimate Partner Violence?
- Seat Belt use (in MVA)
- Positioning of Seat Belt?
- See Seat Belt Use in Pregnancy for proper positioning
- Other medical history
- Maternal drug use
- Comorbidity (e.g. Diabetes Mellitus, Asthma)
- Symptoms
- Vaginal Bleeding
- Vaginal fluid discharge
- Uterine contractions
- Fetal movement
- Abdominal Pain, Pelvic Pain or Low Back Pain
VII. Classification
- Minor Trauma (90% of cases)
- Major Trauma
- Rapid compression, deceleration or shearing forces (e.g. Motor Vehicle Accident)
- Abdominal Injury
- Pain reported
- Vaginal Bleeding
- Amniotic fluid loss
- Decreased fetal movement
VIII. Exam: Indications for Advanced Cardiac Life Support (ACLS)
- Cardiac Arrest
- Unresponsive
- Respiratory arrest or airway compromise
- Blood Pressure <80/40 mmHg
- Heart Rate <50 or >140 beats/min
- Viable fetus with Fetal Heart Rate <110 or >160 beats/min
IX. Exam: Primary Survey
- See Primary Survey
- Airway
- Gastric aspiration increased risk in pregnancy
- Intubation
- Anticipate a difficult airway in all pregnant Trauma patients
- Increased Mallampati Score (Grade IV scores are more common)
- Hypoxia with apnea is more rapid (decreased Total Lung Capacity, increased Oxygen Consumption)
- Airway managament failure rate is 8 fold higher in pregnancy than the general population
- Rapid Sequence Intubation (RSI) and sedation agents are described below
- Endotracheal Intubation in pregnancy is difficult (1 failure in 224 patients)
- Regardless of ideal Anesthesia conditions
- Quinn (2013) Br J Anaesth 110(1): 74-80 [PubMed]
- Endotracheal Tube size
- Airway edema in pregnancy
- Use smaller Endotracheal Tube (6.5 to 7.0 mm internal diameter)
- Breathing
- Oxygenation
- Rapid oxygen desaturation occurs with apnea in pregnancy
- Oxygen Consumption increases by 20% in pregnancy (due to maternal and fetal requirements)
- Apply Supplemental Oxygen early as indicated
- Maintain maternal Oxygen Saturation >95% to ensure adequate fetal oxygenation
- Intubation Preoxygenation and Apneic Oxygenation during intubation
- Decreases risk of significant oxygen desaturation during intubation attempt
- Rapid oxygen desaturation occurs with apnea in pregnancy
- Chest Tubes
- Diaphragm is higher in pregnancy (especially in third trimester)
- Place 1-2 interspaces higher (above 4th to 5th intercostal space) in later pregnancy to stay in pleural space
- Consider using chest Ultrasound to define the pleural space and level of diaphragm during exhalation
- Oxygenation
- Circulation
- Cardiovascular physiology in pregnancy
- Cardiac ouput increases by 40% by 10 weeks gestation
- RBC volume increases 20-30%
- Plasma volume increases 50%
- Relative Tachycardia and Hypotension are typical by the second trimester of pregnancy
- Blood Pressure decreases by 10-15 mmHg by the second trimester
- Heart Rate decreases by 5-15 beats per minute by the second trimester
- Pregnant women can lose 10-20% of Blood Volume before it is reflected by Tachycardia and Hypotension
- Decreased uterine Blood Flow is an early compensatory mechanism in maternal Hemorrhage
- Fetal Distress is an early indicator of maternal vascular collapse
- Cardiac ouput increases by 40% by 10 weeks gestation
- Hypotension and Tachycardia
- Obtain early 2 large bore IVs in seriously injured pregnant women
- Assume Tachycardia and Hypotension are due to Hemorrhage in Obstetrical Trauma
- Hypotension and Tachycardia are ominous, late changes in Obstetrical Trauma
- Fetal Heart Rate monitoring is a maternal Vital Sign as an earlier indicator of obstetrical Hemorrhage
- Supine Hypotension syndrome (aortocaval compression syndrome)
- Uterine compression on aorta and inferior vena cava while supine
- Leads to 30% decreased Cardiac Output after 20 weeks gestation
- Supine position results in Hypotension
- Prevention
- Uterine compression on aorta and inferior vena cava while supine
- Cardiovascular physiology in pregnancy
-
Disability
- Brief Neurologic Exam including Glasgow Coma Scale (GCS) as with non-pregnant Secondary Survey
- Differential diagnosis for Altered Level of Consciousness in pregnancy includes Eclampsia
- Exposure
- Complete exposure as with non-pregnant Secondary Survey
- Define injuries related to both nonintentional Trauma and Intimate Partner Violence
X. Exam: Secondary Survey
- See Secondary Survey
- Pregnancy specific focus areas
- Vaginal exam (defer if suspected placental previa)
- Blood or amniotic fluid
- Vaginal Lacerations
- Uterine exam
- Abdominal exam (fundal height, tenderness)
- Pelvic exam and speculum exam (with caution)
- Evaluate for vaginal blood, amniotic fluid
- Tocometry for contractions
- Most accurate marker of Fetal Distress (initiate as soon as possible)
- Fetal Monitoring for Fetal Distress
- Maternal evaluation takes priority over fetus
- Fetal Heart Tones act as the canary in the coal mine
- Detects significant uterine Trauma or hemodynamic instability
- Fetal Heart Tones change well before maternal Vital Signs
- Vaginal exam (defer if suspected placental previa)
-
Abdominal Injury risk increases
- Uterine injury (e.g. Placental Abruption)
- Uterus exposed out of pelvic brim by 8-12 weeks and is subcostal by 36 weeks
- Uterus Blood Flow increases 10 fold over baseline in the third trimester (up to 600 ml/minute)
- Uterus is highest risk abdominal organ to penetrating injury
- Placenta susceptible to shearing forces
- Rapid acceleration or deceleration
- Highest risk in third trimester
- Bladder injury
- Stomach often full due to delayed emptying
- Aspiration risk in Trauma and surgery
- Insert a Nasogastric Tube in semiconscious or unconscious pregnant women
- Splenic Injury
- Uterine injury (e.g. Placental Abruption)
-
Pelvic Fractures associated with high morbidity
- Bladder injury
- Injury to Urethra
- Retroperitoneal bleeding
- Fetal Skull Fracture (42% mortality rate)
XI. Labs
- See Diagnostic Testing in Trauma
- Initial
- Complete Blood Count (normal findings in pregnancy)
- Leukocytosis
- White Blood Cell Count normally 12 to 18,000 in third trimester
- Relative, dilutional Anemia (plasma volume expands more than RBC mass)
- Compare Hemoglobin And Hematocrit with prior labs
- Leukocytosis
- Blood Type and Rh Factor (and type and cross match as indicated)
- See RhoGAM administration for Rh Negative patients as below
- Complete Blood Count (normal findings in pregnancy)
- Additional studies in major Trauma
- Coagulation Factors (INR, PTT and Fibrinogen)
- Fibrinogen is high in pregnancy normally
- Comprehensive metabolic panel (Electrolytes, Renal Function tests, Liver Function Tests)
- Arterial Blood Gas
- Minute Ventilation increases in pregnancy by up to 40%, resulting in Respiratory Alkalosis
- pCO2 is suppressed more in pregnancy at baseline, dropping to 30 mmHg
- pCO2 40 mmHg may signal impending Respiratory Failure in pregnancy
- Kleihauer-Betke Test
- Variable recommendations regarding utility
- Useful beyond dosing RhoGAM in Rh Negative patients
- Detects fetomaternal transfusion and acts as a marker of fetomaternal Hemorrhage
- RhoGAM is typically given in standard dosing to all women who are Rh Negative
- Exceptions are described below
- Coagulation Factors (INR, PTT and Fibrinogen)
XII. Diagnostics
- See EKG Changes During Pregnancy
-
Fetal Monitoring (4 hours minimum)
- Continuous Tocometry
- Abnormal Tocometry (8 contractions/hour for 4 hours) has a 100% Test Sensitivity for Placental Abruption
- Observe for 24 hours if 3-7 contractions per hour
- Fetal Heart Rate monitoring
- Continuous Electronic Fetal Monitoring for >20-24 weeks gestation (and intermittent monitoring if earlier)
- Monitor as a maternal Vital Sign that is an early detector of impending vascular compromise
- Continuous Tocometry
XIII. Imaging
- See Radiation Exposure in Pregnancy
- Precautions
- Maternal safety is the first consideration in Obstetrical Trauma
- Do not delay ionizing radiation imaging (XRay or CT) in maternal hemodynamic instability
- The risk of missing serious Traumatic Injury in hemodynamic instability far outweighs Fetal Radiation Exposure
- Radiologist Consultation
- Consider Consultation with radiologist when considering multiple ionizing radiation studies in pregnancy
- However, do not delay critical imaging in the Unstable Patient
- Nonionizing radiation imaging (Ultrasound or MRI) is preferred in pregnancy if no delays
- Ionizing radiation imaging follows ALARA rule (As Low as Reasonably Achievable)
- However Gadolinium contrast is not recommended in pregnancy (risk of nephrogenic systemic fibrosis)
- Maternal safety is the first consideration in Obstetrical Trauma
- Standard XRays
- Complete critical XRays as in non-pregnant patients
- Maternal evaluation takes priority (but be selective where possible)
- Radiation exposure
- Plain film XRay risk is low
- Risk of fetal adverse effects low if rads <5
- Even a pan-scan has <5 rads
- Shield Uterus as much as possible
- Radiation exposure risk is even lower if Gestational age >15 weeks
- Chest XRay (normal findings in pregnancy)
- Decreased inspiration
- Wide Mediastinum
- Complete critical XRays as in non-pregnant patients
-
FAST Exam
- Unchanged in pregnancy (but can capture Fetal Heart Tones on pelvic view)
- Best Test Sensitivity for Hemorrhage in first trimester of pregnancy
- Decreased Test Sensitivity for Hemorrhage on FAST Exam after the first trimester
-
Obstetric Ultrasound
- See Obstetric Ultrasound
- Indications
- Distinguishes maternal and Fetal Heart Rates
- Confirms live fetus
- Identifies placental location
- Determines amniotic fluid index
- Establishes Gestational age (for viability >24 weeks gestation)
- Emergency physicians can accurately and rapidly estimate Gestational age by Bedside Ultrasound
-
Ultrasound misses most Placental Abruptions
- Tests sensitivity for abruption: 20-50% (NPV 53%)
- However, Ultrasound is highly specific for abruption (88% PPV, 96% Test Specificity)
- Glantz (2002) Ultrasound Med 21(8): 837-40 [PubMed]
- Precautions
- Avoid doppler mode to measure Fetal Heart Rate (use M-Mode instead)
- Doppler mode (and especially power doppler mode) is associated with high fetal energy exposures
-
CT Abdomen and Pelvis With Contrast
- Fetal radiation dose: 25 mGy
- Radiation exposure <50 mGy are not associated with fetal loss or anomaly
- CT is indicated in stable pregnant patients with significant Blunt Abdominal Trauma
- CT Is under-performed in high mechanism injuries
- Avoiding indicated CT risks missing serious or life threatening maternal injury
- See Placental Abruption for CT and Ultrasound findings
- CT Is under-performed in high mechanism injuries
- Fetal radiation dose: 25 mGy
XIV. Management: High risk indicators for 24 hours intense monitoring
- Vaginal Bleeding
- Spontaneous Rupture of Membranes
- Fetal heart tone abnormality (Non-reassuring Fetal Heart Tracing)
- Uterine contractions for >4 hours
- Consider Placental Abruption (8/hour for 4 hours)
- Continued monitoring for 24 hours is recommended for 6 or more contractions per hour
- Occasional contractions are common after Trauma
- Usually <3-7 contractions per hour
- Contractions usually resolve within 4 hours
- Avoid Tocolytics (delays abruption diagnosis)
- Uterine tenderness
- Abdominal Pain
- Positive Kleihauer-Betke test
- Serum Fibrinogen <200 mg/dl
- High risk injury
- Pedestrian struck by motor vehicle
- High speed Motor Vehicle Accident
XV. Management: Maternal Stabilization (Primary Survey)
- Follow ACLS and ATLS protocols
- See ABC Management
- See Trauma Primary Survey
- See Trauma Secondary Survey
- Treat non-obstetrical injuries as needed
- Consult obstetrics early for viable fetus >23 weeks gestation
- Emergent consult for contractions, Placental Abruption, Uterine Rupture
- Maternal health is first priority
- See Primary Survey as above
- Oxygen Supplementation to maintain Oxygen Saturation >95%
-
Fetal Heart Tones are a maternal Vital Sign and an early predictor of maternal vascular collapse
- Fetal Heart Tones change well before maternal Vital Signs in hemodynamic compromise
- Fetal mortality approaches 100% in maternal shock
- Decrease uterine compression of Great Vessels (see above)
- Left lateral decubitus position or displace Uterus manually to side
-
Intravenous Fluids (Lactated Ringers or Normal Saline)
- Obtain 2 large bore IVs early
- See Hypotension and Tachycardia concerns as above
- Consider early pRBC transfusion with Rh Negative blood (until typed) if significant Hemorrhage suspected
- Volume Resuscitation is far preferred over Vasopressors (less uteroplacental insufficiency)
- Consider Tranexamic Acid for bleeding Obstetrical Trauma presenting in the first 3 hours
- Administer RhoGAM if Rh Negative
- Kleihauer-Betke test may be useful as a marker of fetomaternal Hemorrhage (regardless of Rh status)
- Administer one full dose (RhoGAM 300 mcg) in all Rh Negative patients with Obstetrical Trauma
- Administer regardless of Gestational age (some recommend RhoGAM 50 mcg if <12 weeks gestation)
- Administer even in minor Trauma (with the exception of minor isolated Extremity Injury)
- Rh Antigen develops with 0.1 ml of fetal blood in maternal circulation
- Consider in suspected large volume fetomaternal Hemorrhage (fetal blood in maternal circulation >30 ml)
- May indicate increased RhoGAM dose (discuss with obstetrics)
- Pregnancy specific pitfalls
XVI. Management: Rapid Sequence Induction (RSI) and Post-Intubation Sedation
- Rapid Sequence Induction (RSI)
- Post-Intubation Sedation
- Propofol
- Preferred initial agent in hemodynamically stable patients
- Dose: 20-40 mg bolus, then 20-40 mcg/kg/min infusion
- Ketamine
- Reserve for patients with significant Hypotension
- Dose: 10-80 mcg/kg/min infusion
- Dexmedetomidine
- Safe agent, but use requires experience in dosing (often used in postpartum ecclampsia)
- Dose: 1 mcg/kg bolus over 10-20 min, then 0.2 to 1.4 mcg/kg/hour infusion
- Fentanyl
- Consider as adjunct
- Dose: 1 to 1.5 mcg/kg bolus followed by 1 to 1.5 mcg/kg/h infusion
- Other agents
- Midazolam
- Other agents are preferred
- Midazolam
- Propofol
- References
- Rebel EM: Post Intubation Sedation for Pregnant Patients
XVII. Management: Surgical indications (laparotomy)
- Peritonitis
- Hemodynamic instability
- Burn Injury with burn area >50%
- Disseminated Intravascular Coagulation (DIC)
-
Placental Abruption
- High risk for catastrophic complication
- Common in Obstetrical Trauma
- Occurs in 5% of what is initially considered mild blunt Trauma
- Occurs in 50% of severe injury
-
Hemorrhage may be concealed and only present with Abdominal Pain
- Ultrasound or CT Abdomen/Pelvis may be required
- Continuous external Fetal Monitoring with Fetal Distress may be the only indicator of Placental Abruption
- Abnormal Tocometry (8 contractions/hour for 4 hours) has a 100% Test Sensitivity for Placental Abruption
-
Uterine Rupture
- Uncommon (<1% of severe Trauma) but carries a high mortality risk
- CT Abdomen has best Test Sensitivity (significantly better than Ultrasound)
- Fetal mortality 12-20% (up to 100% in Trauma) and maternal mortality 10% (up to 20-65% in Trauma)
- Viable fetus and Fetal Distress
- Fetal viability in obstetric Trauma is variable per institution, and varies between 20 and 26 weeks
- Fetal viability outside of Trauma and with exact dates is typically defined as 23 weeks
- Post-mortem C-Section is indicated if Maternal Cardiac Arrest and viable fetus
- Decision to proceed with post-mortem ceserean must be made within 4-5 minutes of maternal death
-
Penetrating Trauma
- Uterine penetration with viable fetus and Fetal Distress is an indication for ceserean section
- Otherwise, uterine defect is repaired surgically and mother and fetus are observed closely
- Gravid Uterus may protect against visceral injury
-
Maternal Cardiac Arrest
- See Perimortem Ceserean Section
- Start within 4 minutes of persistent Maternal Cardiac Arrest if fundal height >20 cm
- Increases likelihood of ROSC in mother
- Decreases aortocaval compression and increasing Preload and Cardiac Output
- Improves perinatal outcomes
- Concurrent measures
- Cardiopulmonary Resuscitation and ACLS protocol
- Broad spectrum Antibiotics
XVIII. Management: Procedural Sedation
- See Procedural Sedation
- See above for precautions
- Preferred Sedatives
- Methohexital
- Other Sedatives that are less ideal
- Propofol (no Teratogenicity, but limited data)
- Midazolam (despite that Benzodiazepines are category D)
- Of Benzodiazepines, Midazolam has best safety profile in pregnancy (slowest placental transmission)
- Preferred Opioid Analgesics
- Preferred Local Anesthetics
- References
- Acker, Koval and Leeper (2017) Crit Dec Emerg Med 31(4): 3-13
XIX. Management: Fetus
- Document Fetal Heart Tones
- No fetal Resuscitation if Fetal Heart Tones absent
- Monitor Fetal Heart Tones as a maternal Vital Sign
- Acts as an early indicator of maternal blood loss
- Fetal Distress precedes maternal Hypotension and Tachycardia
- Fetal Distress is a marker of impending maternal vascular collapse
- Determine Gestational age (as accurately as possible)
- Methods
- See obstetrical Ultrasound as above to estimate Gestational age if not known
- Fundal height may be used as an initial approximation
- Do not use fundal height for making viability decisions
- Gestational age >20-24 weeks: See below
- Gestational age <20-24 weeks or EFW < 500 grams
- No Resuscitation of fetus
- Methods
-
Gestational age of >20-24 week gestation
- Consider Obstetric Ultrasound (see imaging above)
- Consider Betamethasone to improve Fetal Lung Maturity
- Indicated for anticipated imminent delivery in Gestational age 24 to 34 weeks
- Administer to mother Betamethasone 12 mg IM every 24 hours for 2 doses
- Efficacy of monitoring
- Abnormal findings poorly predict fetal outcome
- Poor sensitivity and Specificity
- Normal: Reassuring for home discharge
- References
- Abnormal findings poorly predict fetal outcome
- Protocol: Observe for signs of Placental Abruption
- Contraction indications for delivery
- Consider if 8 or more per hour for >4 hours
- Observe for 24 hours if 3-7 contractions per hour
- Avoid Tocolytics after Trauma
- May delay Placental Abruption diagnosis
- Contractions resolve spontaneously in 50-90% of cases
- Consider if 8 or more per hour for >4 hours
- Fetal heart tone indications for delivery
- Contraction indications for delivery
- High risk: 24 hours of monitoring
- See high risk indicators above
- Low risk: 4 hours (ACOG) to 6 hours (ACS)
- Perform electronic Fetal Monitoring and tocometry
- See Indications for discharge (below)
- Consider delivery for 8 or more contractions per hour (suggestive of Placental Abruption)
- Extend monitoring to 24 hours if 3-7 contractions per hour
XX. Disposition
- Major Trauma
- Consider transfer to Trauma Center with obstetrics support
- Tocometry and continuous Fetal Monitoring for at least 24 hours if indicated
- See High risk indicators for 24 hours intense monitoring (as above)
-
General measures prior to emergency discharge
- RhoGAM in nearly all Rh Negative patients
- See maternal Secondary Survey above
- Exception may be an isolated injury (e.g. upper extremity) distant from the Abdomen
- Tetanus Toxoid
- Administer if Tetanus Vaccine has not already been given this pregnancy
- Safe in pregnancy
- Analgesics
- Confirm safety in cases of Intimate Partner Violence
- Ask patient specifically about Intimate Partner Violence
- Assess for safe environment
- Assess for Major Depression and Suicidality
- Obstetric Ultrasound
- Indicated if monitoring was needed beyond >4 hour minimum
- RhoGAM in nearly all Rh Negative patients
- Indications for discharge
- See High risk indicators for 24 hours intense monitoring (as above)
- Contraction resolution
- Fetal Heart Tones reassuring
- No signs of Rupture of Membranes
- No uterine tenderness
- No Vaginal Bleeding
- Indications to return to labor and delivery
- Vaginal Bleeding
- Decreased fetal movement
- Rupture of Membranes
- Persistent uterine contractions
- Abdominal Pain
XXI. Prevention
-
Intimate Partner Violence (IPV)
- See Intimate Partner Violence
- Universal screening for IPV is recommended in pregnancy (abuse often increases in pregnancy)
- Abdomen is the most common target for assaults
-
Motor Vehicle Accident related injuries
- MVAs affect 2% of pregnant women with a resulting 368 maternal deaths per year in the U.S.
- Air Bags should not be disabled
- Pregnant women should use Seat Belts (positioned appropriately)
- See Seat Belt Use in Pregnancy for positioning
XXII. References
- Krywko and Jennings (2018) Crit Dec Emerg Med 32(4): 3-11
- Murphy (2000) ALSO, F:1-20
- Brown in Majoewsky (2012) EM:Rap 13(1): 11
- Hirashima (2014) Crit Dec Emerg Med 28(6):12-18
- Baerga-Varela (2000) Mayo Clin Proc 75:1243-8 [PubMed]
- Grossman (2004) Am Fam Physician 70:1303-13 [PubMed]
- Murphy (2014) Am Fam Physician 90(10): 717-22 [PubMed]