International Rhinologic Society Rhinology 0300-0729 2026 06 14 The Amsterdam Classification of Completeness of Endoscopic Sinus Surgery (ACCESS): a new CT-based scoring system grading the extent of surgery EN S. Reitsma Department of Otorhinolaryngology, Amsterdam University Medical Centers, location AMC, Amsterdam, The Netherlands G.F.J.P.M. Adriaensen Department of Otorhinolaryngology, Amsterdam University Medical Centers, location AMC, Amsterdam, The Netherlands M.E. Cornet Department of Otorhinolaryngology, Amsterdam University Medical Centers, location AMC, Amsterdam, The Netherlands R.M. van Haastert Department of Otorhinolaryngology, Amsterdam University Medical Centers, location AMC, Amsterdam, The Netherlands M.H. Raftopulos Department of Otorhinolaryngology, Amsterdam University Medical Centers, location AMC, Amsterdam, The Netherlands W.J. Fokkens Department of Otorhinolaryngology, Amsterdam University Medical Centers, location AMC, Amsterdam, The Netherlands Journal Article 2555 10.4193/Rhin20.165 BACKGROUND: A debate is ongoing on the role of the extent of sinus surgery in disease control in chronic rhinosinusitis (CRS). The newly developed Amsterdam Classification on Completeness of Endoscopic Sinus Surgery (ACCESS) score provides a way to quantify extent of surgery. This study aimed to validate the ACCESS scoring system and to report its interrater agreement compared to the widely used Lund-Mackay (LM) scoring system. METHODOLOGY: Forty hand-picked anonymized computed tomography scans of sinuses of patients with varying pathology and degree of previous sinus surgery were independently scored by six rhinologists. Interrater agreement was determined by the intraclass correlation (ICC) statistic. RESULTS: The interrater agreement of the ACCESS score was excellent, comparable to the LM score. The ACCESS interrater agreement was not influenced by degree of opacification or diagnosis. The ACCESS score reliably measured predicted differences induced by sinus surgery. CONCLUSIONS: the ACCESS score is an easy-to-use valid tool to assess extent of sinus surgery with an excellent interrater agreement. Further validation in a random group of CRS cases is required.