Upper lip bite test compared to modified Mallampati test in predicting difficult airway in obstetrics: A prospective observational study.

Difficult airway and intubation can have dangerous sequela for patients if not managed promptly. This issue is even more challenging among obstetric patients. Several studies have aimed to determine whether the test to predict a difficult airway or difficult intubation, is higher in accuracy. This study aims to compare the upper lip bite test with the modified Mallampati test in predicting difficult airway among obstetric patients. During this prospective observational study, 184 adult pregnant women, with ASA physical status of II, were enrolled. Difficult intubations of Cormack-Lehane grade III and IV were defined as difficult airways and difficult intubation in this study. Upper lip bite test, modified Mallampati test, thyromental distance and sternomental distance were noted for all patients. Modified Mallampati test, upper lip bite test and sternomental distance had highest specificity. Based on regression analysis, body mass index and Cormack-Lehane grade have a significant association. Modified Mallampati test was the most accurate test for predicting difficult airway. The best cut-off points of thyromental distance and sternomental distance in our study were 5cm and 15cm, respectively, by receiver operating characteristic curve analysis. Based on the results of the present study, it can be concluded that in the obstetric population, modified Mallampati test is practically the best test for predicting difficult airway. However, combining this test with upper lip bite test, thyromental distance and sternomental distance might result in better diagnostic accuracy.