Outcomes:
(1) contractions or preterm labor
(2) fetal death
Risk factors for contractions or preterm labor:
(1) gestational age > 35 weeks
(2) physical assault
(3) pedestrian collision
Risk factors for fetal death:
(3) pedestrian collision
(4) ejection from a motor vehicle
(5) motorcycle collision
(7) maternal death
(8) maternal tachycardia
(9) abnormal fetal heart rate (fetal tachycardia, bradycardia, absent fetal heart tones)
(10) vehicle accident with a lack of restraints (seat belt, shoulder harness et al)
(11) maternal Injury Severity Score > 9
Several of these risk factors were associated with an increased risk of placental abruptions (4, 8, 11, 9).
If none of these risk factors are present, then the patient should be monitored for at least 6 hours and then can be discharged.
If one or more of the risk factors are present, then the patient should be monitored for at least 24 hours.
Although not listed as a risk factor, I would be tempted to keep a pregnant woman with multiple gestation for the longer observation period. I could not find mention of this population in the discussion.
