Table 1.

Comparison of several methods for visualizing hydatid elements in hydatid fluid samplesa

Method of:Comment(s)
Concentration
 FiltrationPractical for high-volume samples. Difficult with viscous samples. Convenient microscopical examination of filters requires special measures for decreasing the relative visibility of the pores (i.e., high-contrast stains or, better, epifluorescence microscopy).
 CentrifugationExamination of sediment poses no problems. May be inconvenient for high-volume, clear samples. Recommended whenever possible.
Examination
 Unstained wet mountSimplest. Low contrast (enhanced in phase-contrast microscopy, but debris become sharper too). No permanent record possible.
 Unstained, fixed dry mountUnder violet excitation light (405 nm), hooklets appear bright green and fluorescent. Recommended if available.
 Gram stainNo staining.
 Auramine-rhodamine stainNo staining.
 Ziehl-Neelsen stainUnder transmitted light, staining appears light and irregular.
Under green excitation light (546 nm), staining appears very bright red and fluorescent. Recommended if available.
 Wheatley trichrome stainHooklets stain uniformly but lightly. Laborious.
 Ryan trichrome blue stainExcellent results. Laborious. Recommended.
 Baxby stainBackground stains too intensely.
 Modified Baxby stainGood results. Simple, quick, and cheap. Recommended.
  • a Examination is by transmitted-light microscopy unless otherwise stated.