Abdomen-only CT enables adequate assessment of maternal solid organs in pregnant women being examined for blunt abdominal trauma—and has the added benefit of reducing fetal radiation exposure as compared with full abdominopelvic CT.
This combination should make the technique a sound choice for certain cases, according to a study published ahead of print in the American Journal of Roentgenology.
The study was conducted by Michael T. Corwin, MD, and colleagues at UC-Davis.
The team examined the cases of 35 abdominally traumatized pregnant patients, mean age 26.2 years, who had CT of the abdomen and pelvis at their institution over a 10-year period.
To identify specific injuries, two blinded radiologists reviewed CT images of the limited and full scanning studies.
Then the researchers computed fetal dose profiles and estimated fetal dose reductions in both scatter and primary radiation.
Their key finding on dose reduction: In women scanned with abdomen-only CT, fetuses at five, 20, and 40 weeks of gestation would have received an estimated 4.3 percent, 26.2 percent and 59.9 percent of the dose expected from full abdominopelvic CT.
Meanwhile, performing linear regression analysis, they found high correlation between gestational age and distance of the fetus to the iliac crests.
Due to fetal growth over time, the dose-reduction effect decreased with increasing gestational age.
In their discussion, Corwin et al. note several limitations inherent in their study, among them its relatively long study period. As this resulted in CT protocols with varying dose parameters, the researchers could not perform calculations of actual fetal doses.
They also acknowledge their small sample and the study’s retrospective nature.
Nevertheless, they conclude, CT of the abdomen only is “a potentially effective technique to reduce fetal radiation exposure compared with full abdominopelvic CT. This protocol enables assessment of the maternal solid organs and is potentially effective in selected cases of maternal blunt abdominal trauma.”