Pregnancy Question Before a Thyroid Uptake Study
A 29-year-old woman is booked for a thyroid uptake and scan with I-123 to investigate thyrotoxicosis. She is accompanied by her 3-year-old daughter. At the pre-scan interview she mentions that her periods have been irregular and she is not sure whether she might be pregnant; her last menstrual period was about 7 weeks ago. She has not done a home pregnancy test. She also asks whether her daughter can stay in the waiting room during the study because no one else is available to watch her. The department uses I-123 capsules, and the protocol includes imaging at 4 and 24 hours.
1. How should the technologist proceed regarding the possible pregnancy before administering I-123?
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The technologist should treat possible pregnancy as a hard stop until clarified. Standard practice is to ask about pregnancy and breastfeeding, and when there is uncertainty (irregular menses, no test), to perform or arrange a pregnancy test per department policy and confirm the result before administering any radiopharmaceutical. I-123 is taken up by the thyroid and can deliver dose to the fetus; fetal thyroid begins concentrating iodine at roughly 10–12 weeks, but the general principle of avoiding unnecessary fetal radiation applies from the outset.
The decision to proceed or defer belongs to the supervising physician and the referring clinician, with informed discussion of risk and benefit. The technologist should not administer the dose "because the protocol is booked," and should not rely on the patient's uncertainty. If pregnancy is confirmed or cannot be excluded, the study should be postponed and the referring physician notified. If the patient is not pregnant, document the negative test and proceed. The technologist should also ask about breastfeeding, since I-123 requires interruption of breastfeeding per physician guidance.
2. What should the technologist advise about the 3-year-old daughter accompanying the patient?
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The technologist should explain that the child should not accompany the patient into the hot lab or scan room and should not be used to provide comfort or restraint during imaging. The patient will be radioactive after I-123 administration, particularly during the uptake period, and close prolonged contact should be limited per radiation-safety guidance. The technologist should arrange for the child to remain in the waiting area with supervision, or ask the patient to reschedule with childcare if supervision cannot be arranged.
Practical guidance includes limiting close contact (holding, lap sitting) during the uptake period, maintaining distance where feasible, and following the physician's/radiation safety officer's instructions about contact precautions and duration. The technologist should not allow the child into the imaging room, and should not give definitive dose estimates beyond departmental/RSO guidance. If the study is postponed for pregnancy testing, the childcare issue is moot for that visit but should be planned for the rescheduled appointment.