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Updated: Aug 30, 2026
Point-of-Care Ultrasound: A Review of Ultrasound Parameters for Predicting Difficult Airways
Published on: April 7, 2023
Variability of the carina-incisor distance as assessed by endoscopic ultrasound
P F Rice1, T L D Crosby, S A Roberts
1Department of Radiology, University Hospital of Wales, Cardiff & Vale NHS Trust, Cardiff, UK.
Aim:
The purpose of this study is to demonstrate variability of the carina-incisor distance (CID), and define morphological factors associated with this.
Materials And Methods:
The carina is clearly visualised on endoscopic ultrasound (EUS), and the CID was measured in 50 patients (29 men, 21 women) undergoing EUS for various indications (30 oesophageal cancer, 20 other) with Olympus UM-20 (used in 24 cases) or MH-908 (used in 26 cases) radial echoendoscopes. Patient height and weight were compared with CID using Pearson's correlation coefficient.
Results:
Mean CID was 25.7 cm, with a range of 20.5-29 cm (SD +/- 1.99). There was no difference between the measured CID in the oesophageal cancer and non-oesophageal cancer groups, or between the two types of echoendoscope. There was highly significant positive correlation between patient height and CID (r = +0.750; P < or = 0.01).
Conclusion:
This study demonstrates considerable variability of the CID from 20.5-29 cm. It is no longer appropriate to assume a 'normal' carinal level of 25 cm in all patients. In this study, if the carina was accepted to lie at 25 cm, this would have led to radiation therapy missing macroscopic disease, a so called 'geographic miss', in nine of the 50 (18%) patients. We now routinely record the level of the CID, the upper and lower extent of the primary tumour and lymph-node metastases with reference to the incisor teeth. This is simple to perform and may assist in radiotherapy planning by reducing the geographic miss rate.
