RESUMO
Myringotomy is a well-accepted method for diagnosing and treating otitis media in dogs having an intact tympanic membrane. In a recent study, the contamination rate of middle ear aspirates from the external ear canal via myringotomy was 67%. To evaluate the iatrogenic contamination rate of the middle ear aspirates by material from the ear canal, using a novel technique: Vertical access to the tympanic membrane from beneath the patient. Thirty-six ears from 20 canine Fresh cadavers with a CT scan negative for otitis externa and otitis media were video-otoscopically flushed with the ear upside. The instillation of the fluorescent dye into the ear canal and immediate retrieval were performed. With the patient positioned on a custom-made fenestrated table plate, a modified video-otoscopically guided myringotomy approaching the tympanum vertically from underneath, was performed. Contamination rates were assessed by the visual detection of fluorescent dye within the aspirated fluid, either by yellow staining solely, or a positive fluorescence test. Cytology and microbial cultivation were accomplished. Middle ear sample contamination by the material from the ear canal was identified in 2 of 36 (5.55%) ears. Neither a change in colour nor fluorescence was detected in 34 of 36 (94.44%) middle ear samples. Sixteen of 36 (44.44%) external ear canal samples and 4 of 36 (11.11%) middle ear aspirates had positive bacterial culture. This novel technique is a promising method for middle ear material collection in patients with concurrent otitis externa.
