[1] Univ Hosp Linkoping, Fac Hlth Sci, Dept Clin & Expt Med, Div Surg, S-58185 Linkoping, Sweden
[2] Cty Council Ostergotland, Dept Surg, Linkoping, Sweden
[3] Karolinska Inst, Dept Mol Med & Surg, Stockholm, Sweden
[4] Karolinska Univ Hosp, Ctr Digest Dis, Div Coloproctol, Stockholm, Sweden
[5] St Marks Hosp & Acad Inst, Harrow, England
[6] Imperial Coll London, Dept Surg & Canc, London, England
[7] Univ Gothenburg, Inst Clin Sci, Sahlgrenska Acad, Dept Surg, Gothenburg, Sweden
[8] Sahlgrens Univ Hosp, Dept Surg, Reg Vastra Gotaland, Gothenburg, Sweden