aDepartment of Visceral, Vascular and Endocrine Surgery, Martin Luther University Halle-Wittenberg, Halle (Saale)

bDepartment of General, Visceral and Transplantation Surgery, Division of Endocrine Surgery, University of Duisburg-Essen, Essen, Germany

Correspondence to Andreas Machens, MD, Department of Visceral, Vascular, and Endocrine Surgery, Martin Luther University Halle-Wittenberg, Ernst-Grube-Straße 40, D-06097 Halle (Saale), Germany. Tel: +49 345 557-2314; fax: +49 345 557-2551; e-mail: [email protected]