[en] The risks of radiation during pregnancy are well established. There is a risk of somatic effects, genetic effects occurring in subsequent generations and mental retardation if the fetus is irradiated in the critical 8-15 week period when organogenesis occurs. It is imperative that the unintended irradiation of the fetus is avoided. Whilst fetal risks have been appreciated for some time, the International Commission on Radiological Protection has never issued practical guidance. However, many national bodies have developed such guidance. In many centres the 10-day and 28-day rules have been variously applied. The purpose of this paper is to review various sources of advice and to highlight three practical implementation issues. These are: 1. Referral could mean more than one examination is performed. 2. The application of the concept of justification to elective procedures. 3. Practical implementation issues. (author)