Comparison of Modified Mallampati Score and Ultrasonographic Airway Assessment in Predicting Ease of Glottic Visualization: A Prospective Diagnostic Accuracy Study at a Tertiary Care Hospital in Pakistan

Introduction: The accuracy of preoperative airway assessment remains a challenging issue. The modified Mallampati (MP) scoring system has been commonly employed, though with poor predictive accuracy. The ultrasonographic measurement of skin-to-epiglottic distance (SED) has been proposed as an objective tool. We evaluated the accuracy of MP scoring and ultrasonographic measurement of SED in predicting easy glottic visualization based on Cormack-Lehane grading during direct laryngoscopy. Methods: This prospective observational diagnostic accuracy study involved 400 adult patients who underwent elective surgery under general anesthesia with an American Society of Anesthesiologists (ASA) grade of I and II. Preoperative MP score and SED by ultrasound examination were performed. The degree of glottic visualization was graded according to the Cormack-Lehane scale. Easy direct laryngoscopy was categorized as a Cormack-Lehane scale of I and II, while difficult direct laryngoscopy was categorized as a Cormack-Lehane scale of III and IV. Results: A significant association was observed between SED and Cormack-Lehane (CL) grade (p < 0.001). The mean SED increased progressively with worsening CL grade (p < 0.001). The area under the ROC curve (AUC) for SED was 0.98 compared with 0.50 for the MP score. At a cutoff >19.5 mm, SED demonstrated 100% sensitivity and 89.95% specificity. The MP score (>3.5) showed sensitivity of 6.25% and specificity of 99.46%. On multivariable analysis, SED was the only independent predictor of difficult laryngoscopy (OR 11.29, 95% CI 4.24-30.07; p < 0.001). Conclusion: Ultrasonographic SED is a highly accurate and independent predictor of difficult glottic visualization and outperforms the modified Mallampati score. Incorporating airway ultrasound into routine preoperative assessments may improve the prediction of difficult glottic visualization.