A Prospective Observational Study Comparing the Upper Lip Bite Test with the Modified Mallampati Score as a Predictor of Difficult Intubation in Patients Undergoing Elective Surgeries Under General Anaesthesia

Abstract

Introduction: Difficult tracheal intubation remains a major concern in anaesthetic practice, contributing to
significant perioperative morbidity and mortality. Accurate preoperative airway assessment is critical to
prevent complications such as hypoxia, brain injury, and cardiac arrest. Among the various bedside tests,
the Modified Mallampati Test (MMT) and the Upper Lip Bite Test (ULBT) are simple, non-invasive, and widely
used. However, their predictive efficacy remains debated.
Objective: To compare the diagnostic accuracy of ULBT and MMT in predicting difficult intubation using
the Intubation Difficulty Score (IDS) in patients undergoing elective surgeries under general anaesthesia.
Materials And Methods: A prospective observational study was conducted on 102 adult patients (ASA I–II),
aged 18–60 years, undergoing elective surgery at Adichunchanagiri Institute of Medical Sciences, Karnataka.
Preoperative assessment included ULBT and MMT classification. Intraoperative intubation difficulty was
evaluated using the IDS. A score 5 indicated difficult intubation. Statistical analysis was performed using
chi-square tests, and diagnostic indices were calculated.
Results: Out of 102 patients, difficult intubation was observed in 18 (17.6%). ULBT showed a sensitivity of
90.9%, specificity of 95.7%, and diagnostic accuracy of 97.06%, significantly outperforming MMT (sensitivity:
18.2%, specificity: 75.3%, accuracy: 70.6%). The ULBT demonstrated a statistically significant association
with IDS (p lt; 0.001), whereas MMT did not have a statistically significant association (p = 0.731).
Conclusion: ULBT is a superior predictor of difficult intubation compared to MMT and should be considered
a reliable tool for preoperative airway assessment in elective surgeries.