Patients were retrospectively divided into 2 groups according to the instruments used for division of the cystic artery and duct as well as for dissection of the liver bed : 121 patients in whom dissection and coagulation were performed using monopolar coagulation and 43 patients who were all treated with the ultrasonically activated scalpel harmonic ACE ( Ethicon Endo-Surgery ) as the sole instrument used in the whole procedure .