Safety margin for the preservation of the nasoseptal artery during trans-nasal endoscopic approach.

Background: The introduction of the nasoseptal flap for the reconstruction of extended endoscopic approaches decreased the incidence of postoperative fistula. In order to preserve the septal vascular pedicles, many have started to prepare the flap systematically, prior to the opening of the sphenoid rostrum. The aim of this study is to obtain an average measure of the location of the posterior septal artery using the upper edge of the choana as a landmark.

Methods: Ten cadaveric heads, fixed with formaldehyde and injected with colored silicone, were studied. The course, branching pattern and dominance of the branches of the posterior septal artery were recognized, as well as the distance in of its superior and lower branches respect to the medial upper edge of the choana.

Results: In all cases, the posterior septal artery enters as an only vessel through the sphenopalatine foramen. In its sphenoid segment, over the sphenoid rostrum, the posterior septal artery divides into its upper and lower branches, in most cases, laterally to the sphenoid ostium (70%, N.=14). The lower branch was dominant in 60% of the cases (N.=12). Regarding the mean distance in millimeters from the medial upper edge of the choana to the superior branch, it was 14.45±0.4102 (18-11.5) and, to the lower branch, 10.9±0.4682 (14-7).

Conclusions: A rostrum opening to 15 mm over the upper edge of the choana is safe to avoid vascular complications, and to be able to prepare a viable nasoseptal flap only if it is necessary.