During preoperative airway assessment, thyromental distance is measured from the thyroid notch to the mental prominence with the head fully extended. Below which value is difficult laryngoscopy predicted?
- A Less than 6.5 cm ✓
- B Less than 4 cm
- C Less than 9 cm
- D Less than 11 cm
Correct answer: A. Less than 6.5 cm
Explanation
B thyromental distance of more than 6.5 cm (roughly three finger breadths) predicts easy laryngoscopy because it reflects adequate mandibular space allowing the tongue to displace during laryngoscopy. B distance under 6.5 cm predicts difficulty. The other values are incorrect thresholds; 4 cm is far too low and would represent an extreme anatomical abnormality rather than the standard screening cut-off.
Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.