Objective: To investigate the anatomical characteristics of the danger zone during dissection of the retrohepatic tunnel and determine its clinical application.
Methods: Anatomical dissections were performed on the liver specimens from 20 adult cadavers, and the clinical data of 27 patients undergoing right hepatectomy with liver hanging maneuver through anterior approach were also collected. The total number of the short hepatic veins entering the inferior vena cava (IVC) at the retrohepatic portion or at the dissecting path of the retrohepatic tunnel was counted separately.
Results: In terms of anatomical findings, the majority of short hepatic veins which drain into the retrohepatic IVC were found to arise from the left and right aspects of the retrohepatic IVC, and were mainly present in the middle and lower third of the retrohepatic IVC segment. At the tunnel dissection route, the openings of the short hepatic veins were mainly present in the lower third of the anterior surface of the retrohepatic IVC with average number of 2.90±1.07, while only one case was found having a short hepatic vein in the upper third and 4 cases were found having a short hepatic vein in the middle third of the retrohepatic IVC. The inferior right hepatic vein was found mostly present in the middle and lower third of the retrohepatic segment and its occurrence rate was 85.0% (17/20). In terms of the intraoperative record, the short hepatic veins entering the retrohepatic IVC were mainly concentrated in the lower third of the course of retrohepatic tunnel, the average number of short hepatic veins was 3.21±1.67, the distance of this zone in most cases from top to bottom was about 3-4 cm and the occurrence rate of the inferior right hepatic vein in this zone was 85.2%. Of the 27 patients, only one case had a short hepatic vein entering the anterior middle segment of the retrohepatic IVC. 
Conclusion: The danger zone of the retrohepatic tunnel is located in the anterior surface of the lower segment of retrohepatic IVC with a distance of 3-4 cm (from top to bottom), where a few short hepatic veins along with the inferior right hepatic vein enter the retrohepatic IVC. This area has unique anatomical characteristics. The key to the success of creation of the retrohepatic tunnel is based on a strong knowledge of the anatomy of this zone and then its dissection in the anatomical plane.