Although self-administered antigen tests are widely available, anatomical knowledge of nasal anatomy in the general population is limited. Cerebrospinal fluid leakage has been reported in multiple cases following damage to the roof of the nasal cavity due to accidental penetration of the cribriform plate of the ethmoid bone. Methods: Images of anatomical prosections used for teaching in the Dissection Room of the Faculty of Medicine of the University of Barcelona were obtained to illustrate the viable horizontal pathway to the nasopharynx through the inferior meatus, below the inferior turbinate. Screenshots from publicly available videos produced by the author demonstrating perpendicular swab insertion were analyzed, and multiethnic illustrative images were taken from staff volunteers. Publicly available instructions for patients included in the first eight nasal antigen tests for self-diagnosis authorized in Spain in 2021 were reviewed. Results: Most of the initially authorized antigen tests (all but one) still recommended in 2025 a vertical swab insertion. However, successful insertion into the inferior meatus towards the nasopharynx can be achieved with a perpendicular approach. A schematic illustration for free use is provided. Conclusion: Swab instructions should indicate an insertion perpendicular to the face to access the inferior meatus safely and reduce the risk of injury to the ethmoidal cells.
Anna Puigdellívol-Sánchez (Fri,) studied this question.