False-positive guaiac testing with iodine.

The guaiac-impregnated test slide (Hemoccult) used in testing for occult blood in the stool gave a false-positive reaction in a trauma patient when a povidone-iodine antiseptic solution (Betadine) was used prior to the insertion of a urinary catheter. Laboratory testing using serial dilutions of povidone-iodine solutions indicates that as little as 0.005 mL… (More)