DIRECT WET SMEAR: Quality Control

1. Check the working iodine solution each time it is used or periodically (once a week). The iodine solution should be free of any signs of bacterial or fungal contamination.

2. The color of the iodine should be that of strong tea (discard if it is too light).

3. Protozoan cysts stained with iodine should contain yellow-gold cytoplasm, brown glycogen material, and paler refractile nuclei. The chromatoidal bodies may not be as clearly visible as they were in a saline mount. Human white blood cells (buffy coat cells) mixed with negative stool can be used as a quality control (QC) specimen. The human cells when mixed with negative stool can be used as a quality control specimen. The human cells will stain with the same color as that seen in the protozoa.