Contrast-enhanced CT for PE poses no risk to neonatal thyroid function

A retrospective single-center study involving 350 pregnant women indicates that contrast-enhanced CT to diagnose suspected pulmonary embolism poses no risk to the thyroid function of neonats.

Dr. T. Claire Alleyne and colleagues at the Women and Infants Hospital of Rhode Island in Providence retrospectively evaluated 350 pregnant women who underwent multislice CT for suspected PE at the hospital from 2004 to 2008. Public health screening records of their newborn infants were examined for T4 thyroxine and thyroid-stimulating hormone.

Contrast dosage administered to the women ranged from 100 cc of 300 mgI/mL of iohexol (Omnipaque) to 150 cc of 350 mgI/mL of the agent.

Alleyne and colleagues found that all newborns had T4 levels deemed appropriate for their gestational age. One newborn, however, had normal T4 but abnormal thyroid-stimulating hormone recorded on the second day of life. The child's TSH level normalized four days later.

The finding led Alleyne to conclude that fears about iodinated contrast media and newborn thyroid function are very likely unfounded. The study's results can be explained by the short-term exposure involved with the contrast-enhanced procedure, the rapid elimination of contrast by maternal kidneys, the physical characteristics of iohexol, and the long duration between exposure and newborn screening, she said.

The findings are limited by the single-center nature of the trial and possibly by undersampling for a postnatal syndrome that affects only one in 20,000 live births, Alleyne said. Still, a literature search associated with the trial suggests that it involved more subjects than any other study to consider this issue, she said.