What is the ten-day rule and what is its status?
‘Ten day rule’ was postulated by ICRP for woman of reproductive age. It states that “whenever possible, one should confine the radiological examination of the lower abdomen and pelvis to the 10-day interval following the onset of menstruation.” The original proposal was for 14 days, but this was reduced to 10 days to account for the variability of the human menstrual cycle. In most situations, there is growing evidence that a strict adherence to the “ten-day rule” may be unnecessarily restrictive. When the number of cells in the conceptus is small and their nature is not yet specialized, the effect of damage to these cells is most likely to take the form of failure to implant, or of an undetectable death of the conceptus; malformations are unlikely or very rare. Since organogenesis starts 3 to 5 weeks post-conception, it was felt that radiation exposure in early pregnancy couldn’t result in malformation. The main risk is that of abortion if the radiation exposure results in death of th
