The Cormack-Lehane grading system classifies airway views during direct laryngoscopy based upon the visible anatomical structures.

Modified Cormack-Lehane classification[1][2]
Grade Visible structures Approximate frequency Likelihood of difficult intubation
1 Full view of glottis 68-74% <1%
2a Partial view of glottis 21-24% 4.3-13.4%
2b Only posterior extremity of glottis and/or arytenoid cartilages 3.3-6.5% 65-67.4%
3 Only epiglottis 1.2-1.6% 80-87.5%
4 Neither glottis nor epiglottis very rare very likely


  1. Yentis, S. M.; Lee, D. J. (1998). "Evaluation of an improved scoring system for the grading of direct laryngoscopy". Anaesthesia. 53 (11): 1041–1044. doi:10.1046/j.1365-2044.1998.00605.x. ISSN 0003-2409. PMID 10023271.
  2. Koh, L. K. D.; Kong, C. E.; Ip-Yam, P. C. (2002). "The modified Cormack-Lehane score for the grading of direct laryngoscopy: evaluation in the Asian population". Anaesthesia and Intensive Care. 30 (1): 48–51. doi:10.1177/0310057X0203000109. ISSN 0310-057X. PMID 11939440.