The term trauma refers to physical injury, usually that occurs rapidly. Trauma can happen outside of pregnancy or, of course, during pregnancy. In fact, trauma occurs in roughly 1 out of 12 pregnancies, and so it is one of the most common pregnancy complications. About 70 percent of pregnancy trauma results from motor vehicle accidents (MVAs), but another common cause is falling. When you are pregnant, you are susceptible to falling because your balance gets thrown out of whack due to your body’s center of gravity shifting during late pregnancy, and due to the muscles of the lower back being strained as the anterior (front) abdominal muscles are stretched, thus weakening your posture. Often, pregnancy trauma is minor to moderate after a fall, for instance if a woman stumbles down two or three stairs, but severe trauma also can occur for a variety of reasons, such as improper use of seatbelts. Some pregnant women may be tempted to push the shoulder belt aside, for instance, which is dangerous since it’s the shoulder belt that keeps your upper body from moving forward as the vehicle decelerates rapidly. Without the shoulder belt in place, the airbag is not as effective; in fact, without a seatbelt, the airbag itself can do you harm. In particular, an MVA can impart an especially high force on the abdomen. Unfortunately, one other major cause of trauma in pregnant women is domestic violence and rape.
As for diagnosis of trauma to the abdomen, the main procedure is called a Focused Assessment with Sonography in Trauma (FAST) exam. To perform FAST, the examiner applies gel to your skin and then does an abdominal ultrasound scan similar to the ultrasonography that is done routinely in your pregnancy checkpups, except in this case the priority is to look for organ damage and for blood inside the abdomen and pelvis. When you have a FAST, neither you nor your fetus are exposed to ionizing radiation. In many cases, however, doctors may also need to check your head and neck, abdomen, or pelvis with plain radiography (simple X-ray scans) or with computed tomography (CT) imaging, which gives you higher X-ray doses than plain radiography.
Although we live in a society that worries much about radiation, it is dangerous to refuse imaging after trauma, because the danger of failing to detect internal damage is far greater than the danger of radiation effects, both for you and your fetus. Ionizing radiation can cause birth defects, especially when exposure happens around 8 to 15 weeks gestation, but risks must be balanced against benefits. Clinical guidelines actually require that doctors employ ionizing radiation to diagnose trauma when needed during pregnancy, since the risk of birth defects is significant only when radiation dose exceeds 0.05 Gray. During a simple X-ray scan, or a CT scan, even a CT scan of the pelvis, the radiation dosage is far below the 0.05 Gray threshold, but the risk of the fetus dying as a result of blood loss or other problems inside your body is grave. There is another type of scanning called Magnetic Resonance Imaging (MRI), which often provides as much information as CT without exposing you to ionizing radiation; however, MRI takes longer to perform, so often it is not appropriate for evaluating emergency pregnancy trauma, a setting in which surgeons require very accurate, timely information. On the other hand, after a relatively modest accident, such as tripping with possible fracture of an ankle bone, doctors typically will order a simple X-ray scan of your lower leg and foot. This provides very good information, such as whether there is a fracture, whether the fracture is complicated with shifting of the bone or simply a crack, and whether the fracture is inside a joint, or not, yet with only a very minute radiation dosage. Furthermore, modern X-ray equipment projects X-ray beams with extreme accuracy to the location that needs to be imaged. This is quite different from X-ray machines of bygone days that used to spread the radiation around the room. Because the radiation is so focused with modern machines, when getting an X-ray scan of your foot, you do not even need a lead apron placed over your belly –yet rarely will X-ray operators not cover such a patient with an apron! The reason is that they believe that you would be worried about your baby and that the responsible party, such as the hospital, could be sued for not using the apron in the event that your baby were to suffer birth defects that have developed for other reasons. This thinking is legalistic, but irrational from the perspective of medicine and biology.
In any case, refusing imaging due to fear of radiation would be extremely unwise, since trauma can cause damage to internal organs, severe blood loss, severe orthopedic injuries, infections inside the body, and other complications that can lead to long-term disability or death, if not recognized and treated. Furthermore, a traumatic event that puts your health and life at risk can harm or kill your baby too. In the perspective of a trauma surgeon, what is good for you, the mother, is good for the baby. This includes diagnostic tests, surgical procedures, and medication on which your health and life depend.
Medications that you may receive in the course of your trauma treatment include anesthetics and other painkillers, and antibiotics. You may also receive medications that alter the force of heart contractions and your blood pressure. Physicians will choose whichever medication is least harmful to the fetus whenever possible, but the life of the mother is always the priority.