1. MVZ “Im Altstadtquartier”, General Surgery , Magdeburg , Germany
2. Otto-von-Guericke University at Magdeburg, Institute for Quality Assurance in Operative Medicine , Magdeburg , Germany
3. Department of General, Abdominal, Vascular and Transplant Surgery , Otto-von-Guericke University at Magdeburg with University Hospital , Magdeburg , Germany
4. Department of General and Abdominal Surgery , Municipal Hospital (“Klinikum Magdeburg gGmbH”) , Magdeburg , Germany