Georgios C Sotiropoulos1, Nikolaos Machairas2. 1. Second Department of Propedeutic Surgery, National and Kapodistrian University of Athens, 11527 Athens, Greece. Electronic address: geosotirop@med.uoa.gr. 2. Second Department of Propedeutic Surgery, National and Kapodistrian University of Athens, 11527 Athens, Greece.