[1] Sahlgrens Univ Hosp, Dept Surg, SSORG, SE-41685 Gothenburg, Sweden
[2] Alingsas Hosp, Dept Surg, Alingsas, Sweden
[3] Dept Surg, Roskilde, Denmark
[4] Roskilde Hosp, Roskilde, Denmark
[5] Univ Copenhagen, Herlev Hosp, Copenhagen, Denmark
[6] Caritas Clin St Josef, Dept Surg, Regensburg, Germany
[7] VUmc Univ Med Ctr, Amsterdam, Netherlands