[1] Jichi Med Univ, Dept Surg, 3311-1 Yakushiji, Shimotsuke, Tochigi 3290498, Japan
[2] Allegheny Gen Hosp, Dept Surg, 320 East North Ave, Pittsburgh, PA 15212 USA
[3] Fukushima Med Univ, Aizu Med Ctr, Dept Coloproctol, 21 Kawahigashi, Aizu Wakamatsu, Fukushima 9693492, Japan