Mineral Oil Scabies Preparation From Under the Fingernail

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A convenient and painless way to obtain a mineral oil scabies preparation from under the fingernail is to use the tip of a disposable hyfrecator, readily available in most dermatology practices for use in electrosurgery (Figure 2). Using the blunt end of the hyfrecator tip for the mineral oil preparation would be done without attachment to the full apparatus.

FIGURE 2. A disposable hyfrecator tip (black arrow).

The hyponychium of the fingernail is prepared with mineral oil, which aids in collecting and suspending the material obtained from under the nail plate. Using the blunt end of the hyfrecator tip, material from underneath the fingernail is removed using a gentle sweeping motion (Figure 3). The specimen is then analyzed under the microscope similar to a routine mineral oil scabies preparation. This method can be utilized by health care providers for easy and painless diagnosis of scabies.

FIGURE 3. The blunt tip of the hyfrecator electrode is used to sweep under the fingernail to painlessly obtain Sarcoptes scabiei to diagnose scabies.

Practice Implications

Use of a blunt hyfrecator tip to extract S scabiei from underneath the fingernail plate can be used for efficient diagnosis of scabies. This technique can be implemented in any clinic where blunt-tip hyfrecator electrodes are available. Using a gentle sweeping motion, the blunt-tip hyfrecator allows the provider to extract material from under the fingernail for diagnosis. The material obtained is used to prepare a mineral oil scabies preparation for direct microscopic analysis.

This technique can diagnose scabies efficiently, and treatment can be initiated promptly. Use of a disposable blunt-tip hyfrecator for scabies extraction is a novel technique that can be added to the armamentarium of tools to diagnose scabies, which includes traditional mineral oil preparation and dermoscopy.


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