Therapeutic abortion is recommended after embryo/fetus exposure exceeding what dose?

• A. 5 rem
• B. 10 rem
• C. 20 rem
• D. 50 rem

Answer: (B)

Ionizing radiation can harm a developing embryo or fetus, and there is a threshold at which the potential risks become significant enough to seriously consider termination. The dose commonly cited for this consideration is about 10 rem (0.1 Gy). Exposures at or above this level are associated with a greater risk of adverse fetal outcomes, so counseling and discussion with the patient are warranted. Doses much lower than that carry smaller or negligible demonstrated risk, while higher doses increase risk further. This threshold is a longstanding teaching point used in exam material to indicate when therapeutic abortion might be discussed, though real-world decisions always involve careful counseling and assessment of gestational age and overall risk.