Imaging of Trauma in Pregnancy

Trauma and accidental injuries complicate 6-7% of all pregnancies [1], and are usually due to motor vehicle accidents, domestic abuse or assaults, and falls. Common adverse consequences include uterine contractions, preterm labor or delivery, and placental abruption. Fetal or maternal demise is rare. In many cases, external fetal monitoring and ultrasound may be adequate for assessment, including detection of placental abruption or uterine rupture (the most serious complication) and documentation of fetal well being [1-3]. That said, trauma to the pregnant patient must be considered with the utmost seriousness because even minor trauma can cause fetal demise [4]. The cardinal principle in the management of trauma in pregnancy is that there can be no fetal survival without maternal survival, with the rare exception of the gravely injured mother late in pregnancy where urgent Cesarean section may allow for fetal survival. From an imaging perspective, ultrasound is an excellent tool for initial evaluation of the traumatized pregnant patient, but CT is the preferred modality when clinical or ultrasound findings suggest visceral injuries unaccompanied by intraperitoneal hemorrhage, or injuries of the chest, mediastinum, aorta, spine, retroperitoneum, bowel, bladder, and bones [5]. MRI is not a practical option for rapid evaluation of all these body parts in an unstable patient after trauma. Placental infarction or abruption typically appears at CT as a single avascular area of varying size that extends from the placental base to the placental surface [6]. High attenuation in the nonplacental portion of the uterus indicates contusion, tear, or partial uterine disruption Loss of amniotic fluid into the maternal peritoneum or free fetal parts in the maternal abdomen indicate an obstetric catastrophe, but it may be difficult to determine if free intraperitoneal fluid is amniotic fluid or hemorrhage from a maternal visceral injury [6].

Key point: Ultrasound may be sufficient for the initial imaging evaluation of a pregnant patient who has sustained trauma, but CT should be performed if serious injury is suspected.