A 24-year-old woman is in a car accident and is taken to an emergency room, where she receives a chest x-ray and a film of her lower spine. It is later discovered that she is 10 weeks pregnant. She should be counseled that
While a 50-rad exposure in the first trimester of pregnancy would be expected to entail a high likelihood of serious fetal damage and wastage, the anticipated fetal exposure for chest x-ray and one film of the lower spine would be less than 1 rad. This is well below the threshold for increased fetal risk, which is generally thought to be 10 rads. High doses of radiation in the first trimester primarily affect developing organ systems such as the hea and limbs; in later pregnancy, the brain is more sensitive. The chromosomes are determined at the moment of conception. Radiation does not alter the karyotype, and determination of the karyotype is not normally indicated for a 24-year-old patient. The incidence of leukemia is raised in children receiving radiation therapy or those exposed to the atomic bomb, but not from such a minimal exposure as here.
The fetus has received 50 rads
Either chorionic villus sampling (CVS) or amniocentesis is advisable to check for fetal chromosomal abnormalities
At 10 weeks, the fetus is paicularly susceptible to derangements of the central nervous system
The fetus has received less than the assumed threshold for radiation damage