Cytocentrifuged biopsy fixative preparation: A simple cost-effective technique facilitating microscopic diagnosis of lumen-dwelling intestinal parasites.

Abstract

Direct microscopic visualization is the most specific method for detecting intestinal parasites and is commonly achieved by stool examination or mucosal biopsy. However, postfixation, the intestinal biopsy fragment is often curled, and the entire surface of the biopsied mucosa is seldom viewed microscopically. Tissue processing further distorts morphology of the organisms and causes diagnostic difficulties. Examining multiple sections for parasite detection is time-consuming and often requires aid of special stains and/or immunohistochemistry. To overcome these disadvantages, we hypothesized that the fixative in which biopsies are transferred may provide a valid representation of the biopsied mucosal surface and therefore aid in the identification of mucosal surface parasites. Formalin in which biopsies were transferred was retained, stored at 4°C and processed with a cytocentrifuge. Totally, 120 consequent duodenal biopsy fixatives were processed in this way and the cytocentrifuged smears visualized after May-Grunwald-Giemsa staining. Findings of these smears were correlated with their corresponding formalin fixed paraffin embedded tissue sections. Cytocentrifuged formalin preparations were found to be representative of the mucosal surface contents. Giardia trophozoites were visualized in 10/120 preparations with distinct morphological characteristics which were seldom appreciable in tissue sections, eliminating the need for special stains. Furthermore, two of the corresponding histology sections did not demonstrate the parasites despite step sections, while in one case few parasites could be identified in the step sections. Cytocentrifuged fixative preparation is a simple and cost-effective technique which can be routinely employed for intestinal parasite characterization.