Scientific letters

The accuracy of patients’ self-reporting of pregnancy and awareness of risks to the fetus from x-ray radiation

Yousuf Vadachia, Hein Els, Savvas Andronikou


Title: An assessment of the accuracy of patients’ self-reporting of pregnancy together with awareness of risks to the fetus from x-ray radiation.

Background: Patients being investigated in a radiology department are exposed to ionising radiation. This radiation may be harmful to a fetus that is inadvertently exposed. Currently, female patients are asked to report if they think they are pregnant to prevent such inadvertent exposure. There has been no study previously at this centre checking the accuracy of patients’ self-reporting of pregnancy. Patient’s need to be informed and educated regarding the risks of exposure a fetus to ionising radiation.

Methods: A prospective study of 125 female outpatients from the ages of 18 to 42 years referred to a tertiary imaging department for investigations was conducted. The study was a questionnaire based survey comparing participants self-reporting of pregnancy with a urine pregnancy test. Participants were also questioned about awareness of risks to fetus from x-ray radiation. Additional data regarding age, previous pregnancies, certainty of date of last menstrual period and contraception was acquired.

Results: Out of a sample size of 125 participants, 119 (95.2%) were certain of not being pregnant and had negative pregnancy tests. 4 (3.2%) were certain of being pregnant and had positive pregnancy tests. 2 (1.6%) participants thought they were not pregnant with pregnancy detected by urine pregnancy test. Thus, patients’ self reporting of pregnancy had a negative predictive value of 98.3%, an accuracy of 98.4%, a specificity of 100% and a sensitivity of 66.7%. Of the 125 respondents 56.8% considered x-ray radiation harmful to the fetus. Of this 56.8% (71 participants) the majority (72%) chose the first trimester as the most radiosensitive period of the pregnancy. Of this 56.8% of the sample size (71 participants), 56.4% (40 participants) chose severity category 3 and 22.5% (16 participants) chose severity category 4 when asked to grade the severity of radiation exposure to the fetus.

Conclusions: Patients’ self reporting of pregnancy compares favourably with urine pregnancy testing in this sample population. Patients’ self reporting has a high accuracy and a high negative predictive value. The majority of patients are aware that x-ray radiation may be harmful to the fetus, however most overestimate the risks to the fetus.

Authors' affiliations

Yousuf Vadachia,

Hein Els, Tygerberg Academic Hospital

Savvas Andronikou,

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ionising radiation; pregnancy

Cite this article

South African Medical Journal 2008;98(11):862.

Article History

Date submitted: 2008-02-04
Date published: 2008-11-07

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