Fig.1-Fig.4 are abbreviated. No liquid contents in cecum (Ce) of Fig.5-Fig.7, and distension limited to small bowel indicate mechanical obstruction. The herniated bowel (black arrow of Fig.14-Fig.16) in left groin is demonstrated. The herniated bowel is confined close to femoral vessels without surpassing pubic symphysis, and the femoral vein is compressed and narrowed in Fig.14 and Fig.15 (white arrowhead) indicating femoral hernia. An inguinal ligament cannot be recognized in conventional axial images (Fig.5-Fig.18). The coronal images (Fig.19-Fig.21) present herniated small bowel (black arrow) to outside of abdominal cavity. Of note, an inguinal ligament (white arrowhead) can be recognized in Fig.19, and bowel herniated below inguinal ligament indicates femoral hernia. On tracking down from A and 1 of Fig.14, black arrowhead of F in Fig.12 indicates the site of the obstruction proving that hernia incarceration is the cause of small bowel obstruction. Surgery revealed incarcerated femoral hernia of small bowel (Fig.A: between black arrowhead) which showed only edema and redness without necrosis.

Reference case (Incarcerated right femoral hernia): A 79-year-old female. Epigastric pain and vomiting developed suddenly several hours ago. There was no fever, and abdomen was soft and flat without tenderness. The irreducible incarcerated hernia in right inguinal region was recognized.

Cecum (Ce) and terminal ileum (Ti) are collapsed in Fig.1 indicating the distended small bowel means mechanical obstruction. Hernia incarceration (black arrow) is demonstrated in Fig.8-Fig.11, and small bowel begins to distend from 1 of Fig.6 and ascends in number order. The incarcerated small bowel is confined close to femoral vessels and kept away from symphysis pubis (white arrow), and Fig.8-Fig.10 show the narrowed right femoral vein (black arrowhead) compared with left side (white arrowhead) indicating femoral hernia. The incarcerated right femoral hernia with viable small bowel was confirmed at surgery.