Safety of C-14-UBT for diagnosis of Helicobacter pylori infection in pregnancy

QUESTION A 29- year-old woman had a carbon 14 urea breath test for diagnosis of Helicobacter pylori infection. At time of consultation, it had been 6 weeks since her last menstrual period. Four weeks after her last menstrual period, the results of a urine pregnancy test were negative. On that day, she received an ionizing radiation dose of 74 KBq (2 mu Ci) carbon 14 urea, followed by the breath test 30 minutes thereafter. Four days later, when the urine pregnancy test results turned positive, she was concerned about the possible effect of her exposure to ionizing radiation on the developing fetus. ANSWER The amount of radiation used in these tests is extremely low-much lower than the amount a pregnant woman is absorbing through natural sources.