Objective vertebral body level with palpation positioning method.MethodsA total of 48 patients underwent elective spinal surgery were selected

including 19 males and 29 females.The ASA classification wasⅠ～Ⅲ.After spinous process of C7 was identified with palpation by a skilled anesthesiologist

palpation was performed to the tail side until spinous process of T7 was identified and marked with T7 a.Then

a low-frequency convex array probe was used to determine the T7 transverse process position performed by an anesthesiologist skilled in spinal ultrasound

and marked with T7 b.Finally

a C-arm X ray machine was used to confirm the exact position of T7 and to determine whether the positioning of T7 aor T7 bwas accurate.The influence of BMI and age to the accuracy of the two positioning methods was analyzed.ResultsThe accuracy rate of ultrasound-assisted positioning method was85.4%

which was significantly higher than that of body surface mark palpation method（52.1%）

and the difference was statistically significant（P<0.05）.Compared with the palpation method

the ultrasound-assisted positioning method reduced the influence of individual differences on the positioning. The influence of BMI and age to the accuracy of the two positioning methods was not statistically significant.ConclusionUltrasound-assisted positioning method is better than body surface mark palpation method

which has important clinical value.