1. Universidad Nacional Mayor de San Marcos, Lima, Peru.
2. Department of Surgery, Daniel Alcides Carrion National Hospital, Callao, Peru.
3. Universidad de San MartÚn de Porres, Lima, Peru.
4. Department of Surgery, ICMDM, Hospital Clinic, Barcelona, Spain.
5. Department of General and Digestive Surgery, Unit Hospital de la Santa Creu I Sant Pau, Universidad Autonoma de Barcelona, Barcelona, Spain.