The value of scintigraphic studies in the assessment of patients with acute or chronic gastrointestinal haemorrhage.

The scintigrams of 76 patients with gastrointestinal bleeding referred over an 8 year period have been reviewed together with their subsequent clinical course. Twenty-five patients had either 99Tcm-sulphur colloid or 99Tcm-labelled red cell scintigraphy to localize a source of active bleeding. Fourteen patients had 99Tcm-sulphur colloid scintigraphy, of which seven were false negatives, two were false positives and two were true positives. Eleven patients had 12 99Tcm-labelled red cell scintigrams, of which three were false negatives, one was a false positive and four were true positives. Fifty patients had 99Tcm-pertechnetate scintigraphy to look for ectopic gastric mucosa in Meckel's diverticula. There were 43 true negatives, two false negatives, two true positives and three false positives in this group. Our results emphasize the need for caution in interpreting nuclear medicine studies in patients with blood loss from the gastrointestinal tract.