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Release: April 30, 2002

NOTE TO EDITORS: the following is adapted from a news release prepared by the American Roentgen Ray Society

New UI policy for imaging pregnant, possibly pregnant patients presented

In an effort to ensure the well-being of pregnant and possibly pregnant patients, University of Iowa researchers have developed a policy to guide the use of radiation to diagnose these patients.

The new policy, which has been in place at the UI Hospitals and Clinics for about six months, will be presented by Meghan Blake, UI medical student, today at the annual meeting of the American Roentgen Ray Society in Atlanta, Ga. Blake was part of the UI team that devised the policy. The team also included Georges El-Khoury, M.D., UI professor of radiology and orthopaedic surgery, and Mark Madsen, Ph.D., UI associate professor of radiology.

In recent years, newer imaging technologies such as multi-slice spiral computed tomography (CT) scanners have become increasingly common in hospitals. These technologies are extremely useful diagnostic tools. For example, in the emergency room a CT scan can rapidly assess a trauma patient's injuries. However, CT imaging uses relatively high doses of ionizing radiation, and exposure to these levels of ionizing radiation may pose a small but real risk for a fetus.

Previous scientific studies show that health risks associated with radiation to the fetus are small for the dose levels delivered by most diagnostic procedures, and no proven effects have been observed for total radiation doses to the fetus less than 5 rem (unit of radiation). However, the UI team reasoned that it made sense to be sure that pregnant patients and the physicians treating them were aware of the potential risks and were in a position to take steps to limit a fetus's exposure to radiation.

"Surprisingly, a search through the medical literature and an informal survey of some academic radiologists yielded a lack of clear policies or specific instructions on this issue," Blake said. "CT and other methods that use radiation are an integral part of how we diagnose acute care patients; it became apparent that a policy was needed."

The UI team devised a policy to establish guidelines for use when a pregnant or potentially pregnant patient requires a CT scan or other form of diagnostic radiology. The overall goal of the policy is to protect the mother because her well being preserves the life of the fetus. However, in achieving this goal, the guidelines lay out measures aimed at keeping the radiation dose to the fetus to a minimum.

The policy eliminates ambiguity, allows for consistency, and helps ease patients' fears, Blake said.

The guidelines apply to all departments in the hospital and mean that all women ages 12 to 55 who require radiography are asked if they are or could be pregnant. If the woman can't communicate, a pregnancy test is done, if time permits.

The policy states that if the woman is pregnant or could be pregnant, then the following applies:

-- If her injuries are not in the pelvic area or area nearby, the fetus would not be in the direct x-ray beam, so the patient is told that there is no scientific evidence of harm to the fetus. Pelvic shielding is used, and the radiation doses are kept as low as possible.

-- If the estimated dose to the fetus is less than 1 rem (from examinations such as a lumbar spine radiograph and an x-ray of the kidney and bladder), the radiologist should consider alternative imaging methods, such as ultrasound. If there is no alternative, the patient must be told there is a minimal risk to the fetus, and all efforts should be made to keep the radiation dose as low as possible.

-- If the estimated dose for the fetus is 1-5 rem (such as with fluoroscopy, abdominal CT, pelvic CT or angiography) an alternative imaging method should be considered. If there is no alternative, the patient must sign an informed consent form indicating she understands that there is a "minimally increased risk" of congenital abnormalities and childhood cancers. Women who are two to 15 weeks pregnant are particularly at risk, noted Blake.

-- If the estimated dose is greater than 5 rem (such as with repeated CT and longer fluoroscopy) the physicist should formally calculate the dose, the patient's chart should document the opinions of the radiologist, the physician who referred the patient for the test and the physicist. The patient must sign an informed consent form that notes her understanding of "increased risk" to the fetus.

In addition, the policy recommends that repeat examinations be eliminated and contrast media (chemicals used to enhance CT imaging) be used with caution.

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