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What We Already Know about This Topic Accurate identification of the cricothyroid membrane is key for success of emergency cricothyrotomy Ultrasound has been reported to identify the cricothyroid membrane more accurately than external palpation in patients with normal neck anatomy What This Article Tells Us That Is New In this randomized clinical trial, 223 adult patients with neck pathologies such as previous neck surgery, irradiation, and/or neck mass who were scheduled for a neck computed-tomography scan were randomly allocated to either the ultrasound group or the external-palpation group Accuracy in identification of the cricothyroid membrane, defined as the distance from a point determined by the computed tomography within 5 mm, was 10-fold greater in the ultrasound group (81%, n = 114) than the external-palpation group (8%, n = 109) Background: Success of a cricothyrotomy is dependent on accurate identification of the cricothyroid membrane. The objective of this study was to compare the accuracy of ultrasonography versus external palpation in localizing the cricothyroid membrane. Methods: In total, 223 subjects with abnormal neck anatomy who were scheduled for neck computed-tomography scan at University Health Network hospitals in Toronto, Canada, were randomized into two groups: external palpation and ultrasound. The localization points of the cricothyroid membrane determined by ultrasonography or external palpation were compared to the reference midpoint (computed-tomography point) of the cricothyroid membrane by a radiologist who was blinded to group allocation. Primary outcome was the accuracy in identification of the cricothyroid membrane, which was measured by digital ruler in millimeters from the computed-tomography point to the ultrasound point or external-palpation point. Success was defined as the proportion of accurate attempts within a 5-mm distance from the computed-tomography point to the ultrasound point or external-palpation point. Results: The percentage of accurate attempts was 10-fold greater in the ultrasound than external-palpation group (81% vs. 8%; 95% CI, 63.6 to 81.3%; P < 0.0001). The mean (SD) distance measured from the external-palpation to computed-tomography point was five-fold greater than the ultrasound to the computed-tomography point (16.6 ± 7.5 vs. 3.4 ± 3.3 mm; 95% CI, 11.67 to 14.70; P < 0.0001). Analysis demonstrated that the risk ratio of inaccurate localization of the cricothyroid membrane was 9.14-fold greater with the external palpation than with the ultrasound (P < 0.0001). There were no adverse events observed. Conclusions: In subjects with poorly defined neck landmarks, ultrasonography is more accurate than external palpation in localizing the cricothyroid membrane.