Thrush Workup

Updated: Jun 21, 2023
  • Author: Mudra Kumar, MD, MRCP, FAAP; Chief Editor: Russell W Steele, MD  more...
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Laboratory Studies

A relatively simple way to confirm the suspected diagnosis of thrush is to scrape the plaques with a tongue blade to reveal an inflamed and/or bleeding base.

Plaques can be cultured, although cultures are rarely indicated. A simple Gram stain demonstrates large, ovoid, gram-positive yeast.

A study by Tooyama et al looked to establish a reliable laboratory test for diagnosing oral candidiasis. The study found that concentrated rinse sampling is suitable for evaluating oral candidiasis. [11]

Diagnosis can be confirmed by simple histologic findings. Pseudohyphae and gram-positive yeast can be seen on Gram stain or with potassium hydroxide stain.