SPECIMEN COLLECTION: Fixatives

Tips and Pitfalls

1. Fixatives should be mixed well with the specimen; ratio of 1 part specimen to 3 parts fixative is recommended.
2. Confirm that fixatives in use are compatible with all relevant tests in the test menu; some stool fixatives are not compatible with the immunoassay test reagents (EIA, FA, immunochromatographic cartridges).
3. Some immunoassay test systems require fresh specimens; check all package inserts prior to use.
4. Organism morphology will not be as good when using non mercury-based fixatives (copper, zinc, single vial systems); however, most organisms can be identified - they just won't look "pretty" or textbook perfect! Endolimax nana cysts may be the most difficult to identify; all protozoan trophozoites will tend to look fairly typical.