Intern Report 5.20

Case Presentation by Dr. Jessica Ruffino

HPI: 25y/o female at 36 weeks GA presents to ED via EMS as a trauma code after MVA.  Patient was a restrained driver, airbags were deployed.  Patient states she was rear-ended while stopped at a traffic signal and hit the car in front of her.  Other vehicle was driving about 25mph.  Patient complains of abdominal pain mostly across lower abdomen.  Patient thinks she is having contractions, unsure of frequency.  Denies loss of fluid.  Last felt fetal movement prior to accident.  Patient denies chest pain, SOB, N/V.  Patient states her pregnancy has been uncomplicated, denies high blood pressure or diabetes.  Patient did not lose consciousness, was ambulating at scene per EMS.

ROS:  Negative except for stated in HPI

PMH:  G1P0.  Denies asthma, diabetes, hypertension

PSH:  None

Medications: Prenatal vitamins

Allergies: NKDA

SH:  Denies alcohol, tobacco, drug use.

Physical Examination:

Vital signs: BP 100/75, HR 100, RR 16, Temp. 36.9°, Pulse ox. 98% on RA

Constitutional: Patient is well nourished, gravid uterus.  No respiratory distress.  Appears anxious.

Head:  Normocephalic, atraumatic.  No tenderness to palpation.

Eyes:  Pupils 3mm bilaterally, round and reactive to light.  EOMI.  No conjunctival pallor.  No scleral icterus.

ENMT:  No hemotypmanum bilaterally.  No rhinorrhea or epistaxis.  Mucous membranes are moist.  No erythema or exudates in throat.

Neck:  In cervical collar.  No c-spine tenderness to palpation, no palpable deformities. Cardiovascular:  S1, S2.  Slightly tachycardic.  Regular rhythm.  No murmurs, rubs or gallops.

Respiratory:  Lungs CTAB.  No wheezes, rhonci or rales.  No tenderness over chest wall.  No palpable crepitus over chest wall or neck.

Gastrointestinal:  Gravid uterus.  Uterus is firm.  Fundus palpable about 15cm above umbilicus.  Tenderness to palpation in lower quadrants bilaterally.  Positive seatbelt sign across abdomen.

Genitourinary:  Sterile speculum exam showed small amount of bright red blood in vaginal canal.  Cervix is closed.

Musculoskeletal:  No TTP or deformities palpated along entire spine.  No obvious deformities.  No swelling.  No dependent edema.  2+ DP pulses bilaterally.

Skin:  No lacerations or rashes.  Positive seatbelt sign across abdomen.

Neuro:  Awake, alert and oriented x 3.  Normal speech.  Strength is 5/5 proximally and distally and bilateral upper and lower extremities.  Sensation to light touch intact throughout.  DTR’s 2+ bilaterally.

A FAST exam was performed and was negative.  Transabdominal ultrasound findings shown below.  FHTs in 140s-160s.

Questions:

1.  What is the most sensitive indicator of placental abruption?

a)  Ultrasound findings

b)  Fetal distress

c)  Vaginal bleeding

d)  Uterine tenderness

2.  Which of the following is true of resuscitation of a pregnant patient with uterus palpable at or above umbilicus who is in cardiopulmonary arrest?

a)  No modifications to resuscitative efforts should be made

b)  Chest compressions should be performed higher on sternum

c)  Manual displacement of uterus to the left should be attempted

d)  Defibrillation is contraindicated

3.  A pregnant patient may lose how much circulating blood volume before manifesting hypotension or clinical signs of shock?

a)  30-35%

b)  10-15%

c)  20-25%

d)  40-45%

 

Correct Answers:

  1. B
  2. C
  3. A

 

Discussion:

Trauma occurs in 6 to 7% of all pregnancies.  It is the leading cause of maternal death due to nonobstetric causes, accounting for close to 50% of fatalities in pregnant women.  The most common causes of injury in pregnancy, in order of frequency, that result in emergency department (ED) visits are motor vehicle crashes (MVCs), interpersonal violence, and falls.  Counseling on proper seatbelt and alcohol use and screening for interpersonal violence may help to reduce the morbidity and mortality rates for pregnant patients.  Although the essential principles of trauma management remain unchanged in the pregnant patient, a number of special points need to be considered.  Pregnancy causes alterations in physiology and anatomy that affect multiple organ systems. Although there are two lives involved, maternal life takes priority.

In blunt trauma, 50 to 70% of all fetal losses result from placental abruption.  Placental separation results when the inelastic placenta shears away from the elastic uterus during sudden deformation of the uterus. Because deceleration forces can be as damaging to the placenta as direct uterine trauma, abruption can occur with little or no external sign of injury to the abdominal wall.  Because all gas exchange between the mother and fetus occurs across the placenta, abruption inhibits the flow of oxygen to the fetus and causes in utero CO2 accumulation. Such hypoxia and acidosis can lead to fetal distress.  Sustained uterine contractions induced by intrauterine hemorrhage also inhibit uterine blood flow, further contributing to fetal hypoxia.

 

 

The diagnosis of abruption is a clinical one, and ultrasonography and the Kleihauer-Betke test are of limited value.  Classical clinical findings of abruption may include vaginal bleeding, abdominal cramps, uterine tenderness, maternal hypovolemia (up to 2 L of blood can accumulate in the gravid uterus), or a change in the fetal heart rate. However, in some trauma studies, as many as 63% of cases showed no evidence of vaginal bleeding.

The most sensitive indicator of placental abruption is fetal distress. Hence, prompt fetal monitoring is a very important assessment technique in trauma during pregnancy. There is also a close linkage of abruption to uterine activity. One study reported that if 12 or more contractions occurred in any hour of a 4-hour cardiotocographic monitoring period, the risk of abruption was 14%; abruption did not occur in this study if contractions occurred less than once every 10 minutes.  Ultrasound (US) is less than 50% accurate as a first-line test in detecting placental abruption.  If the abruption bleeds externally, not enough blood collects to be seen sonographically. Even with significant intrauterine blood accumulation, accurate US diagnosis may be difficult because of placental position (i.e., posterior) and confounding uterine or placental structural conditions.

 

Hemodynamic Changes of Pregnancy (Mean Values)

PARAMETER NONPREGNANT TRIMESTER 1 TRIMESTER 2 TRIMESTER 3
Heart rate (beats/min) 70 78 82 85
Systolic blood pressure (mm Hg) 115 112 112 114
Diastolic blood pressure (mm Hg) 70 60 63 70
Cardiac output (L/min) 4.5 4.5 6 6
Central venous pressure (mm Hg) 9.0 7.5 4.0 3.8
Blood volume (mL) 4000 4200 5000 5600
Hematocrit without iron (%) 40 36 33 34
Hematocrit with iron (%) 40 36 34 36
White blood cell (cell/mm3) 7200 9100 9700 9800

 

The relative hypervolemic state can mislead the clinician during maternal resuscitation after trauma and make clinical findings difficult to interpret.  A pregnant patient may lose 30% to 35% of circulating blood volume before manifesting hypotension or clinical signs of shock.  Uterine arteries constrict, which results in diminished fetal blood flow and tissue oxygenation before significant evidence of maternal hypovolemia appears.

Cardiopulmonary arrest in a pregnant patient must be considered under two scenarios: before fetal viability and after fetal viability. The accepted age of fetal viability varies among institutions, but 22 to 26 weeks is generally considered potentially viable. The uterine fundus is palpable at the umbilicus at 20 weeks. After 20 weeks, the gestational age of the fetus can be estimated by measuring the fundus from the pubic symphysis to the top of the fundus. The fundal height in centimeters corresponds roughly to the gestational age in weeks. Before approximately 22 to 24 weeks’ gestation, all efforts should focus on the mother, with no modifications to CPR.  Beyond 22 weeks or if the gravid uterus can be palpated above the umbilicus, several modifications of CPR should be instituted: (1) the patient should be positioned to minimize aortocaval compression, and (2) appropriate preparations for a potential cesarean section and care of a viable fetus should be made.

Limitation of aortocaval compression is achieved by (1) having someone manually displace the uterus to the left, (2) tilting the patient 15 to 30 degrees on a tiltable table, or (3) placement of a roll or a Cardiff wedge, if available, under the patient’s right hip and flank. The Cardiff wedge provides a tilt of 27%, allowing 80% of the compressive force, compared with CPR in the supine position, which maintains 30% or less of normal cardiac output in nonpregnant adults.  The “human wedge” has been advocated for bystander CPR. In this technique, the patient lies across the thighs of the rescuer, who is in a kneeling position. Despite relatively clear current recommendations regarding resuscitation in pregnancy, there is little research in this area.

 

Massive fetomaternal transplacental hemorrhage causes alloimunization in Rh incompatibility but also endangers the fetus by severe fetal anemia and resulting fetal distress and possible exsanguination. ABO incompatibility causes less severe disease.

The Kleihauer-Betke test identifies fetal cells in a maternal blood sample. Most laboratories screen for FMH of 5 mL or more. Unfortunately, the amount of FMH sufficient to sensitize most Rh-negative women is well below this 5-mL sensitivity level. Therefore, all Rh-negative mothers who have a history of abdominal trauma should receive one prophylactic dose of Rhesus immune globulin (RhIG). In the first trimester, one 50-g dose is used because total fetal blood volume is only 4.2 mL by 12 weeks’ gestation and a 50-g dose covers 5 mL of bleeding. During the second and third trimesters, a 300-?g dose of RhIG is given, which protects against 30 mL of FMH. Beyond 16 weeks’ gestation, the total fetal blood volume reaches 30 mL, so it is quite possible that massive FMH may exceed the efficacy of one 300-g dose of RhIG. Therefore, it is unlikely that a Kleihauer-Betke test is useful in the treatment of severely injured pregnant trauma patients.

 

References:

Rosen’s Emergency Medicine. 7th editon. Pages 252-261.

Tintinelli’s Emergency Medicine.  7th edition.

 

 

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