Pregnancy screening strategies for diagnostic nuclear medicine procedures

Research Doctorate - Doctor of Philosophy (PhD)Nuclear medicine involves the use of ionising radiation to image the physiological functions of the body and to treat certain diseases. Ionising radiation has the potential to cause biological harm and foetal tissue is particularly sensitive especially in the early stages of pregnancy. Although diagnostic nuclear medicine procedures use relatively low levels of radiation, there is still a risk to a foetus if inadvertently exposed during maternal examinations. National and international radiation protection documents recommend that all women of childbearing age be questioned about their pregnancy status prior to any procedure that uses ionising radiation. However, they do not provide any clear guidelines on what constitutes childbearing age, or how to question the patient prior to diagnostic nuclear medicine procedures. This thesis reports on four interconnected research phases: two literature reviews (systematic and narrative), an interview study, a cross-sectional survey, and a Delphi study. The systematic review on the accuracy of pregnancy screening strategies to identify early pregnancy revealed that serum and urine HCG pregnancy tests are highly sensitive. However, urine tests have a high false-negative rate when used in the early stages of pregnancy. The review also revealed that self-assessment of pregnancy is reliable, particularly in the absence of pregnancy. A narrative review of formal methods of consensus development identified the Delphi Technique as the best method for development of consensus statements for identifying/assessing early pregnancy in women patients prior to diagnostic NM scans. Phase two of the research involved a series of semi-structured interviews to investigate current practice and identify any associated problems or difficult to question groups, such as teenagers. The interview findings were used to develop a questionnaire for a National online cross-sectional survey of nuclear medicine personnel in Australia and New Zealand (Phase three). Both studies revealed wide variations in current practice which may lead to inadvertent foetal irradiation. The studies highlighted the need for a consistent approach and the development of consensus guidelines. Finally, a three-round Delphi study was conducted to develop consensus statements regarding questioning patients prior to diagnostic nuclear medicine procedures. The age range for questioning was defined by consensus as 12-55 years. A method for questioning patients was developed which included advice regarding previously identified difficult to question groups. A flowchart was created as a visual aid. Identification of pregnant and potentially pregnant women prior to diagnostic nuclear medicine procedures is imperative to avoid foetal exposure to ionising radiation. This research identified the lack of a consistent approach and developed consensus guidelines for questioning patients about their pregnancy status. The implementation of these consensus guidelines into nuclear medicine practice will help accurately identify pregnancy and minimise any unnecessary foetal irradiation