Prior to ordering multiple x-rays, CTs, fluoroscopies or any combination thereof, physicians treating pregnant women who may have suffered musculoskeletal injuries should consult with a medical physicist to discuss cumulative radiation dosing.
However, excepting for such scenarios as well as for pelvic CTs, radiographic exams are generally safe for both mom and baby-to-be.
Lead author Jonas Matzon, MD, of Thomas Jefferson University in Philadelphia, and colleagues spell out the factors that ought to figure in radiologic evaluations of pregnant orthopedic patients in the August edition of the Journal of the American Academy of Orthopaedic Surgeons.
The review article notes that 5 percent to 8 percent of pregnant women in the U.S. are traumatically injured, with automobile accidents doing the most damage to the women (33.6 percent of injuries during pregnancy) and causing the large majority of fetal deaths (82 percent).
There are risks, both carcinogenic and teratogenic, to consider before plunging in with imaging.
For example, ionizing radiation doses of greater than 100 mGy can cause serious harms—including, if administered in the first trimester, miscarriage, fetal anomalies and developmental delays.
The good news is it would take a lot of radiographic examining to get to that level.
Plain radiographs of a pregnant woman’s extremities and cervical spine expose her fetus to less than 10 mGy, while pelvic CT emits doses of around 35 mGy.
In a summary of previously accepted CT and MRI guidelines, the authors write that the risk of teratogenesis—damage to a fetus in development—is not a major concern after diagnostic pelvic CT studies.
Their advice on other types of imaging risks:
- Risk of carcinogenesis after diagnostic CT: “Key concern after diagnostic pelvic CT studies; should be avoided unless absolutely necessary.”
- Pregnancy termination after diagnostic irradiation: “Exceptionally unlikely that any single diagnostic study would deliver a radiation dose sufficient to justify pregnancy termination.”
- CT contrast media: “Use of iodinated contrast media appears to be safe in pregnancy.”
- MRI: “Most studies show no ill effects, but it is good practice to avoid for elective studies and in first trimester.”
- MRI contrast media: “IV gadolinium is contraindicated and should only be used if absolutely essential.”
- Imaging of trauma: “Ultrasonography may be sufficient for initial imaging, but CT should be performed if serious injury is suspected.”
In elective evaluations, radiography and CT can be used safely and with negligible risk as long as the abdomen isn’t involved and the absorbed fetal dose is less than 5 mGy, write Matzon and colleagues.
“Although great care must be taken to protect the fetus from exposure, most diagnostic studies are generally safe,” they conclude, adding that ultrasound and MRI have proven generally safe as alternative modalities for pregnant patients.