A retrospective audit of cumulative ionising radiation levels in hospitalised pregnant patients

Abstract

Background Among hospitalised patients, diagnostic radiation is possibly used least on pregnant patients due to the fear of ionising radiation on the fetus; however, what levels are currently being prescribed. Aims To assess the cumulative levels of ionising radiation received by pregnant patients during a single admission to a tertiary hospital. Materials and methods A retrospective audit of pregnant patients admitted to Flinders Medical Centre, South Australia, Australia, between 2013 and 2017 inclusive was performed. All procedures utilising ionising radiation were collected including conventional radiology, computed tomography, fluoroscopy and nuclear medicine. Individual and cumulative effective doses for mother and fetus were calculated using patient dose reports and published conversion factors. Results From 547 patients, the median cumulative effective dose was 0.02 mSv and only five patients received more than 10 mSv, with 19.07 mSv the highest dose received. The median fetal cumulative effective dose was 0.01 mSv but only three fetuses received more than 10 mSv, likely due to fetal exclusion in some procedural fields of view. Stays longer than ten days were associated with significantly higher cumulative effective dose, as did those with maternal cardiovascular related admission, for both maternal and fetal exposures. Conclusion These results suggest that pregnant patients are exposed to low doses of ionising radiation, in both individual procedures and cumulative doses. The detrimental risks associated with these levels of ionising radiation are not overt and so clinicians should question which risk is higher, the ionising radiation from the radiological procedures received or the lack of diagnostic information if avoided?

Medical Imaging in Pregnancy: Safety, Appropriate Utilization, and Alternative Modalities for Imaging Pregnant Patients

“…Because of the lower fetal dose, nuclear radiation using a CT pulmonary angiogram scan is the best choice for pregnant mothers. It should also be noted that a thyroid iodine scan is not the best option of medical imaging for pregnant women since iodine 121 and 131 are taken up by the fetus's thyroid and hence contraindicated [ 22 ].…”

Melanoma in pregnancy: Diagnosis and management in early-stage and advanced disease

“…In addition to this, there are potential carcinogenic and mutagenic risks to the foetus, with ongoing debate as to whether this leads to any significant subsequent risk of childhood malignancy [85,86]. In reality, there is no 'safe' level of ionising radiation exposure in pregnancy that is universally accepted, and the general consensus is that attempts should be made to minimise exposure whilst obtaining sufficient clinical information [87]. Studies suggest that there is no increased risk of miscarriage or major malformation/growth restriction at doses of 50 mGy, when compared with the natural background radiation during pregnancy (0.5e1.6 mGy) [88].…”

“…Further studies suggest a 0.1% risk of complications at exposures of > 250 mGy [89], with a typical CT scan of the chest, abdomen and pelvis exposing the foetus to between 10 and 50 mGy per scan [90]. Any potential risks to the foetus should be balanced against the clinical benefit of the imaging study [87], and the stage of pregnancy at which exposure occurs is a key determinate in the level of risk of harm to the foetus. Given these potential risks, it is important to consider the optimal imaging modality in pregnancy, aiming to achieve the highest diagnostic sensitivity with the lowest possible radiation exposure, including avoiding the use of ionising radiation where feasible, with ultrasound (US) imaging and magnetic resonance (MR) imaging the most widely utilised in pregnant women.…”