What are the limitations of radionuclide scanning for evaluation of lower gastrointestinal (GI) bleeding (LGIB)?

Updated: Jul 26, 2019
  • Author: Burt Cagir, MD, FACS; Chief Editor: BS Anand, MD  more...
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Answer

Advantages for radionuclide scans include their noninvasiveness and their high sensitivity. The disadvantages of radionuclide scans include the fact that the scans have a high false localization rate, ranging from approximately 3% to 59%. [53] In 24 publications, the bleeding point was accurately localized in 52%-90% of positive cases, with an average of 86% and incorrect localization of 14%. Because of the high false localization rate (10%-60%) for the bleeding site, performing segmental resections based solely on scintigraphy results is not recommended. Another disadvantage of radionuclide scans is that the scans must be performed during active bleeding.

The difficulty of localization was demonstrated in a study by Hunter et al in which the results of TRBC scanning were incorrect in about 25% of patients. [54] Indeed, eight patients underwent unwarranted surgical procedures based upon the findings of more definitive tests. Poor localization of the source of the bleed in radionuclide scans often is due to the overlapping segments of bowel and the migration of tagged RBCs in the large bowel.

Recurrent LGIB occurs after negative TRBC scintigraphy. Hammond et al reported the overall rebleeding rate to be 27% and concluded that age, sex, bleeding source, use of anticoagulant/antiplatelet agents, length of hospital stay, admission hematocrit (Hct), Hct nadir, and transfusion requirements are not predictive of patients who will rebleed. [55]


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