CT Scans of Pregnant Women Increasing

(HealthDay News) -- Although more pregnant women are getting all types of medical imaging, the number of those getting CT scans has more than doubled over 10 years, Brown University researchers report.

CT exams are not routinely done for pregnant women, but, in some cases, it may be the only way to diagnose life-threatening conditions such as bleeding in the brain, blood clots in the lungs or appendicitis. CT scans expose the fetus to higher levels of radiation than other methods, causing concern that CT scans could harm the developing baby.

"At our institution, utilization of radiological imaging in pregnant women increased 107 percent, comparing 1997 to 2006," said lead researcher Dr. Elizabeth Lazarus, an assistant professor of diagnostic imaging and a radiologist at Rhode Island Hospital in Providence. "The rate of increase was highest for computed tomography (CT)."

Lazarus acknowledged that many people worry that the radiation used in these scans might harm the fetus. However, women need not be overly concerned, she added.

"First of all, it should be stated that radiological imaging is safe during pregnancy and is often used to diagnose potentially life-threatening medical problems," Lazarus said. "The risk of direct radiation to the fetus during pregnancy is a very slight increase in childhood malignancy."

The point of the study is to raise awareness about the increase of imaging in pregnant patients and to possibly encourage the development of protocols that minimize radiation exposure, Lazarus said. For example, MRIs and ultrasound do not expose the patient or fetus to ionizing radiation, she noted.

The report is published in the March 17 online edition of Radiology.

For the study, Lazarus' team looked at the trend in pregnant women undergoing CT, fluoroscopy and plain-film X-ray imaging at Rhode Island Hospital and Women and Infants Hospital from 1997 through 2006.

During the period, the number of these tests on pregnant women increased by 10.1 percent a year. The number of CT exams increased by 25.3 percent per year. These exams involve higher amounts of radiation than many other imaging procedures, the researchers noted.

They looked specifically at 5,270 examinations done on 3,285 patients. During the study period, the number of patients imaged each year increased from 237 to 449, and the number of exams increased from 331 to 732. This is an 89 percent increase in patients and a 121 percent increase in examinations. Yet, during the same period, the number of deliveries increased only 7 percent, Lazarus said.

Although the study did not look at the specific causes of increased imaging in these patients, the finding seemed to follow the trend of increased medical imaging in all patient groups, Lazarus said.

"We know from other studies that imaging, particularly MRI and CT, has been increasing in the general population. The increase in the general population has been attributed to multiple causes, including technological progress and the high yield of radiology in the diagnosis and triage of patients. Our data in pregnant patients closely approximates these more general trends," she said.

Dr. Jorge Guerra, a professor of radiology at the University of Miami Miller School of Medicine, agreed that the number of CT scans has increased, as has all imaging, but the radiation exposure to the fetus is minimal.

"The dose of radiation given to the fetus in any one exam is very low," he said. For pregnant women undergoing a CT, the odds that the infant will develop a fatal childhood cancer directly related to the radiation exposure of the exam is one in 2,000, Guerra said.

Guerra noted that limiting radiation exposure is an important goal, and current doses of radiation are significantly lower than the doses used during the period of the study.

"There are ways to cut down on the levels of radiation by changing the parameters of the CT," he said. "Since 2006, we have become so acutely aware that we are changing the parameters in studies that affect children and women of childbearing age. There is no excessive risk to the patient or to the fetus."

More information
For more on medical imaging, visit the Radiological Society of North America.