Although concentration methods are mostly useful for helminth eggs, they may also increase the likelihood of finding certain protozoan cysts and sporozoan oocysts. Different methods utilizing sedimentation or flotation do exist. Stool specimens can either be fresh or preserved in formalin. The zinc sulfate flotation method is more useful for certain helminth eggs; a sedimentation technique is preferred to recover cysts and oocysts.
The formalin-ethyl acetate sedimentation concentration technique is commonly used. Protocols for this technique can be found
here.
