Rectum is resected and sigmoid colostomy is installed above Fig.1. Because cecum (Ce) is collapsed in Fig.1-Fig.4, the distended small bowel is very likely to be mechanical obstruction. Under the diagnosis as mechanical obstruction, it is basic and essential to search for incarceration of external hernia as a cause. The black arrow in Fig.14-Fig.19 demonstrates an incarcerated bowel in obturator foramen. There is collapsed small bowel (white arrowhead) in Fig.11-Fig.13, which begins to distend from circle number 1 of Fig.10 ascending to circle number 10 of Fig.1 of cephalad side. The incarcerated obturator hernia of small bowel was confirmed at surgery.