Direct Centrifugal Flotation
(Modified Lane Technique)
The modified Lane technique is used to concentrate helminth ova. It is used for detection of the
same types of eggs as the zinc sulfate centrifugal flotation technique. It has an advantage in
being quantitative. It is also quicker to run. It has the disadvantage of requiring slightly more
care.
Procedure
1. Mix a known weight of feces (usually 10 g) with 300 ml of tap water.
2. Mix thoroughly and pour suspension into a 15 ml centrifuge tube.
3. Centrifuge at 1000 rpm for 3 min.
4. Pour off supernatant and add saturated sodium nitrate solution to half fill tube.
5. Resuspend material from bottom of tube and then add enough sodium nitrate solution to fill
tube to within a few drops of the top.
6. Centrifuge at 1000 rpm for 3 min.
7. Add sodium nitrate solution until meniscus is above edge of tube.
8. Without trapping air bubbles, cover with a cover glass.
9. Remove cover slip to a clean slide and systematically search the entire mount for eggs.
Egg Count
For each egg under the cover slip when 10 g feces used, egg count is 2/g.
“
“
5g “
“
4/g.
“
“
4g “
“
5/g.
“
“
2g “
“
10/g.
DIRECT WET SMEAR TECHNIQUE
The first step in the microscopic examination of a fecal specimen for parasites should be the
preparation and examination of a direct wet smear.
PROCEDURE: Smear a small portion of the uncontaminated stool on a microscope slide and
mix it (using an applicator stick) with a few drops of saline. (For detection of helminth
eggs only, tap water may be used in place of saline). Add a cover glass and examine with a
microscope. It must be remembered that the fecal smear must be thin enough to permit
reading of a printed page through it. At the same time, it should not be so thin that the
material floats under the cover glass.