CT evaluation of anatomical variations of the internal jugular veins in Thai adults

Background: The internal jugular vein (IJV) is used to obtain central venous access for various reasons. Awareness of the expected location and anatomic variations of the IJV is very important to avoid inadvertent arterial puncture.

Objective: We evaluated anatomical variations of the IJVs, including diameter, depth from skin surface, relative distance from common carotid artery (CCA) and position in relation to CCA in Thai adults by using CT scan of the neck.

Material and Methods: A total of 77 patients who underwent CT scan of the neck (nasopharynx, larynx) at the Department of Radiology, King Chulalongkorn Memorial Hospital (KCMH) from May 1, 2009 to April 30, 2012 were retrospectively reviewed. The diameter of the IJVs, depth from skin surface and relative distance between the IJVs and CCAs were taken bilaterally. Bilateral CCAs were taken as reference points for measuring the location of the IJVs, recorded as lateral, anterior, medial or posterior position. These parameters were evaluated using the same axial slice at a level of cricoid cartilage, which was compatible with the recommended point for central venous catheter insertion via the IJV. Intra- and interobserver reliability between researcher and another radiologist was assessed by intraclass correlation coefficient (ICC).

Results: The right IJVs were usually larger than the left IJVs (57/77 or 74.0%) with significant difference in diameter (14.9 ± 4.0 mm vs. 11.6 ± 3.8 mm, p <0.0001). The right IJVs were significantly located more superficial than the left IJVs (16.3 ± 4.2 mm vs. 17.0 ± 4.4 mm, p = 0.049). The right IJVs tended to have distance far from the CCAs more than the left IJVs (1.3 ± 0.6 mm vs. 1.2 ± 0.9 mm, p = 0.372). Most of the IJVs located laterally to the CCAs (145/154 or 94.2%). A total of 4/154 IJVs (2.6%) were located anteriorly and 5/154 IJVs (3.2%) were located posteriorly. There were two cases that the posterior position of the IJVs was seen bilaterally. No medially located IJV was found.

Conclusion: There were anatomical variations of the IJVs, including diameter, depth from skin surface, relative distance from the CCAs and position in relation to CCAs, which remained potential risk when jugular venous access was attempted. Awareness of these variations is very important.