Site-Based Comparative Analysis of Sample Collection Through Direct Biopsy and Nasal Swabs for Early Diagnosis of Post-COVID Rhinomaxillary Fungal Infection Using Potassium Hydroxide Mounting: A Retrospective Cohort Study.

Aim: To perform site-based comparative analysis for samples collected from the nasal region and oral cavity subjected to microscopic detection of fungal hyphae in KOH mount in a group of patients with rhinomaxillary mucormycosis. Methodology: Forty patients fulfilled eligibility criteria. The diagnostic outcome of detection of fungal hyphae from the KOH samples obtained was the primary endpoint of the study. Based on this, the samples were grouped into three groups viz-oral, nasal and both. The secondary outcome was to check if there was any diagnostic delay in these three groups of patients. Results: The mean number of days for delayed diagnosis for oral site involvement was 56.33 ± 37.53, for nasal involvement was 32.86 ± 19.53 and for both oral and nasal involvement was 22.00 ± 12.94. This difference was statistically significant at p = 0.03. The mean delay in diagnosis was significantly less when both oral and nasal regions are involved as compared to the only oral region involved at P = 0.01. Conclusion: To avoid the chance of delayed diagnosis or false-negative results, it is best to collect samples from both nasal tissues and the most representative site in the dentoalveolar segment depending on the extensiveness of the disease.