KOH Preparation

CPT CODE: 87220
TEST INFORMATION: The test includes a KOH preparation ONLY. A fungal culture will NOT be performed unless specifically requested.
DAYS PERFORMED: Daily, 800 - 1600
TURNAROUND TIME: 2 hours after receipt of the specimen in the laboratory
CONTAINER TYPE: Sealed sterile container, no preservative; sterile Petri dish (available from Clinical Microbiology Laboratory); Copan Swab II
COLLECTION: Infected hair should be cut with sterile scissors or plucked with sterile forceps and placed in a sealed, sterile container. A Wood`s lamp is useful in the collection of specimens in tinea capitis infections, since hairs infected by most members of the genus Microsporum exhibit fluorescence under a Wood`s lamp. If diseased hair stubs or fluorescent hairs are not apparent, scrape the edge of a scalp lesion with a sterile scalpel. Infected nails should be sampled from beneath the nail to obtain softened material from the nail bed. If unable to obtain adequate material from the nail bed, a scalpel should be utilized to scrape the superficial portions of the nail obtaining subsurface material. Nail clippings are unacceptable. When obtaining a cutaneous specimen, the area to be sampled should first be cleansed with 70% alcohol to remove bacterial contaminants. Typical 'ringworm' lesions should be sampled from the erythematous, peripheral growing margin.Genital specimens should be collected using aseptic technique.
SPECIMEN REQUIREMENTS: Hair, nail scrapings, skin scrapings, genital specimens
REJECTION CRITERIA: Inappropriate specimen container, insufficient specimen volume, specimen received in a preservative, nail clippings
MINIMUM VOLUME: As much as possible of hair, nail scrapings, skin scrapings; two genital swabs
HANDLING INSTRUCTIONS: Specimen should be transported as soon as possible. When transportation is delayed, leave at room temperature.
REFERENCE RANGE: No fungal elements observed
LIMITATIONS OF TEST: The test may require overnight incubation for complete disintegration of keratin. A fungal culture is more sensitive than the KOH preparation; therefore, the KOH Preparation may be negative when the Fungus Culture is positive.
METHODOLOGY: KOH preparation
TEST SYNONYM(S):Potassium Hydroxide Preparation