Imaging Pregnant and Lactating Patients

Abstract

As use of imaging in the evaluation of pregnant and lactating patients continues to increase, misperceptions of radiation and safety risks have proliferated, which has led to often unwarranted concerns among patients and clinicians. When radiologic examinations are appropriately used, the benefits derived from the information gained usually outweigh the risks. This review describes appropriateness and safety issues, estimated doses for imaging examinations that use iodizing radiation (ie, radiography, computed tomography, nuclear scintigraphy, and fluoroscopically guided interventional radiology), radiation risks to the mother and conceptus during various stages of pregnancy, and use of iodinated or gadolinium-based contrast agents and radiotracers in pregnant and lactating women. Maternal radiation risk must be weighed with the potential consequences of missing a life-threatening diagnosis such as pulmonary embolus. Fetal risks (ie, spontaneous abortion, teratogenesis, or carcinogenesis) vary with gestational age and imaging modality and should be considered in the context of the potential benefit of medically necessary diagnostic imaging. When feasible and medically indicated, modalities that do not use ionizing radiation (eg, magnetic resonance imaging) are preferred in pregnant and lactating patients. Radiologists should strive to minimize risks of radiation to the mother and fetus, counsel patients effectively, and promote a realistic understanding of risks related to imaging during pregnancy and lactation.

MRI in pregnancy: Indications and practical considerations

“…Therefore, acoustic damage to the fetus is theoretically not a significant concern. Lending support to this is a recent study including 715 neonates who were exposed to MRI in utero and did not demonstrate any evidence of acoustic damage …”

“…However, one new theoretical risk relates to fetal hearing, in that rapidly switching gradient fields may lead to high levels of acoustic noise in close proximity to the mother and fetus. Much like concerns during the first trimester, no known reports exist describing damage to human fetal hearing resulting from MRI …”

“…The FDA allows a maximum acceptable whole‐body SAR of 4 W/kg, which can increase the body temperature 0.6 °C, for 30 minutes of MRI . Tissue heating is proportional to the tissue's proximity to the scanner and greatest at the maternal body surface, while it approaches negligible levels at the body's center . Therefore, tissue heating has not been considered a serious risk factor when imaging falls within accepted SAR limits .…”

“…Acoustic damage to the fetus is another potential risk of MRI. Fast gradient switching creates 80–120 dB of acoustic noise . Acoustic noise with 120 dB has the potential to cause hearing loss in adults, and 90 dB is the acceptable upper limit of acoustic noise that has the potential to cause permanent damage to the fetal ear .…”

Re: Imaging investigations in pregnancy

“…All investigations, whether a patient is pregnant or not, must be performed with informed consent, the individual having been provided with the most accurate information available. 5 We agree that all efforts should be made to minimise foetal exposure to ionising radiation as a result of investigation of the mother. 3 Additionally it states a threshold of 100 mGy above which foetal malformations, growth retardation and foetal death are possible.…”