What recent changes have influenced the overall quality of the permanent stained smear?
The use of mercury substitutes in PVA generally leads to diminished overall morphology quality of the intestinal protozoa. However, some of the mercury substitutes provide morphologic quality that is close to mercury and allows identification of most of the intestinal protozoa. Differences in detection and identification are usually comparable unless there are very few organisms present; some organisms may be missed using mercury substitutes.
