A role for subtraction scintigraphy in the evaluation of lower gastrointestinal bleeding in the athlete.

While lower gastrointestinal haemorrhage (LGIH) in the athlete tends to be self-limiting in the majority of athletes, recurrent symptoms occur in some athletes. It is important to identify the smaller percentage of athletes in whom risks and recurrence are greater because both their general health and athletic performance might benefit from more rigorous clinical evaluation. Technetium-99m red blood cell ((99m)Tc RBC) scintigraphy is a technique for detection and localisation of LGIH and offers a number of significant advantages over other imaging modalities in the evaluation of LGIH. Nonetheless, there are a number of limitations recognised in (99m)Tc RBC scintigraphic evaluation of LGIH. Subtraction scintigraphy in (99m)Tc RBC evaluation of gastrointestinal haemorrhage may offer a tool to overcome limitations of conventional scintigraphy. In essence, subtracting a nominal 'mask' or reference image from all subsequent images provides a mechanism to view only the information contributed by accumulated bleeding, removing potential sources of both false-positive and false-negative findings. While the limitations of procedures available for the evaluation of LGIH are generally prohibitive of effective application in the obscure bleeding associated with athletic performance, adopting subtraction methods in conjunction with conventional (99m)Tc RBC scintigraphy may offer a valuable tool in identification and localisation of bleeding sites. The general health and athletic performance may be enhanced in some athletes when the underlying cause of bleeding can be more appropriately managed.