DIRECT WET SMEAR: Procedure Limitations

1. Because motility is lost when specimens are placed in preservatives, many laboratories are no longer performing the direct wet smear (primary purpose is to see motility) but are proceeding directly to the concentration and permanent stained smear procedures as a better, more cost-effective use of personnel time. This approach is recommended.

2. Most of the time, results obtained from wet smear examinations should be confirmed by permanent stained smears. Some protozoa are very small and difficult to identify to the species level with just the direct wet smear technique. Confirmation is particularly important in the case of Entamoeba histolytica/E. dispar versus E. coli. Findings from the direct wet smear examination can be reported as "preliminary,'' and the final report can be submitted after the concentration and permanent stain procedures are completed.