Is technetium (Technetium-99m) safe during pregnancy?

From the Guidelines

Technetium can be safely used during pregnancy, specifically low-dose technetium (Tc)-labelled albumin nanocolloid for sentinel lymph node (SLN) biopsy, as stated in the most recent and highest quality study 1. When considering the use of technetium during pregnancy, it is essential to weigh the potential benefits against the risks. The primary concern with technetium is its radioactive nature, which can cross the placenta and potentially expose the developing fetus to radiation. However, the radiation dose from technetium is relatively low compared to other radiopharmaceuticals. Some key points to consider:

• The use of low-dose technetium (Tc)-labelled albumin nanocolloid for SLN biopsy is recommended during pregnancy, as it has been shown to be safe and effective 1.
• Breastfeeding mothers who receive technetium may need to temporarily interrupt breastfeeding for a period recommended by their healthcare provider, typically 24-48 hours depending on the specific procedure.
• If a pregnant woman has already undergone a technetium scan before knowing she was pregnant, she should be reassured that the actual risk is likely very small, as the radiation exposure from a single diagnostic procedure is generally below levels associated with observable harmful effects.
• The benefits and risks of undergoing a diagnostic work-up using technetium should be discussed with the pregnant woman, and the limitations and uncertainties of estimated risk of radiation-induced cancer should also be discussed and placed in the context of the well-understood expected clinical benefits of diagnostic work-up 1.

From the FDA Drug Label

Pregnancy Category C Animal reproduction studies have not been conducted with Technetium Tc 99m Oxidronate It is also not known whether Technetium Tc 99m Oxidronate can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Technetium Tc 99m Oxidronate should be given to a pregnant woman only if clearly needed

Technetium is not considered safe during pregnancy. The FDA drug label indicates that it falls under Pregnancy Category C, meaning that animal reproduction studies have not been conducted, and it is unknown whether the drug can cause fetal harm. Therefore, it should only be given to a pregnant woman if clearly needed 2.

From the Research

Safety of Technetium During Pregnancy

• The use of technetium-99m in pregnant women is considered to be relatively safe when medically necessary, as the doses delivered to the fetus are typically low [<5 mGy] 3.
• Studies have shown that the fetal dose from technetium-99m is lower than the dose known to produce deterministic effects, and the probability of late effects is considered to be low 3.
• The International Commission on Radiological Protection recommends a supplementary dose limit of 2 mSv to the abdominal surface of a pregnant member of staff to protect the fetus 4.
• Fetal doses to nursing staff caring for an adult 99mTc patient have been estimated to vary from 86 microSv to 1.6 microSv, with a ratio of abdominal surface to fetal dose varying from 1.8:1 to 1.5:1 4.
• A case study of a 6-month pregnant woman who underwent a Tc-99m red blood cell bleeding scan showed that the procedure was necessary and the risk of radiation exposure to the fetus was discussed with the patient and the radiation safety officer 5.

Guidelines for Radionuclide Scans During Pregnancy

• Radionuclide scans, including those using technetium-99m, should only be performed during pregnancy when medically necessary and after discussing the risks and benefits with the patient 3, 5.
• The dose of radionuclide should be kept as low as possible without sacrificing radiographic information 3.
• Pregnancy testing should be performed before any procedure that will expose the fetus to >50 mGy 3.
• Alternative imaging modalities, such as MRI or ultrasound, may be considered when possible 6, 7.