Background
Conventional laparoscopic instruments that are used for liver retraction are not suitable for tissue retraction in Lapro-endoscopic single site (LESS) and natural orifice trans-luminal surgery (NOTES) technologies. Bioadhesive retraction systems may overcome the ergonomic difficulties associated with LESS and NOTES soft tissue and solid organ retraction.

Material and Methods
Studies were performed in an ex-vivo porcine liver model where the liver was placed in a scaffold designed to simulate the anatomy of the human liver in the supine position. Body temperature and moisture simulation was achieved by placing the scaffold in a water-bath at 37o. Optimal liver retraction and gallbladder exposure were defined by fixing three coloured labels to the gallbladder fundus, infundibulum and biliary tree. The C3 polymer was reinforced by a plastic disk, then placed over the liver surface.The retraction forces were applied and measured by the Instron connected to the C3 polymer disks by a surgical thread. In all experiments a retraction acceleration force of 1N/sec was applied, to determine the biological tissue adhesion and retraction properties of the C3 polymer.

Results
The mean force required to provide optimal surgical exposure was 4.85N (SD 0.63); and the average duration of polymer adhesion with good liver retraction was 130 minutes (range 17-240 minutes). Optimal C3 polymer adhesion to the liver was reached after a 30s tissue application time.

Conclusion
The adhesion and retraction properties of C3 polymers are encouraging. Bioadhesive films may provide a novel method of organ and tissue retraction in minimal access surgery.