How are skin scrapings used in the workup of scabies?

Updated: Oct 13, 2020
  • Author: Megan Barry, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

Definitive testing relies on the identification of mites or their eggs, eggshell fragments, or scybala. [22] This is best undertaken by placing a drop of mineral oil directly over the burrow on the skin and then superficially scraping longitudinally and laterally across the skin with a scalpel blade. (Avoid causing bleeding.) Scraping 15 or more burrows often produces only 1 or 2 eggs or mites, except in a case of crusted scabies, in which many mites will be present. [43]

The sample is placed on a microscope slide and examined under low and high power. Potassium hydroxide should not be used, since it can dissolve mite pellets. Failure to find mites is common and does not rule out the diagnosis of scabies.


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