 Rationale: Adhesion formation is a frequent complication after abdominal surgery. Adhesion formation might be reduced by laparoscopic surgery, however sound evidence is lacking. Colorectal surgery would be a good clinical model to investigate adhesion formation between open and laparoscopic surgery because of the adhesion formation propensity of colorectal surgery. However, a randomized controlled study to provide direct evidence is unlikely because of large numbers of patients needed for such a trial and the difficulty to check for adhesion formation at second surgery. Therefore we investigate adhesion formation after laparoscopic and open colorectal surgery for malignancy at liver surgery for metastases. 