1. Department of General, Visceral and Transplant Surgery, Hannover Medical School, Hannover, Germany.
2. Department of General and Visceral Surgery, Diakovere Henriettenstift and Friederikenstift, Hannover, Germany.
3. Department of General, Visceral and Vascular Surgery and Coloproctology, Vinzenzkrankenhaus Hannover, Hannover, Germany.