In a Richter's hernia, only part of the circumference of the bowel wall (the antimesenteric border) is trapped in the sac, and it is most common in femoral hernias. A Littre's hernia (A) contains a Meckel's diverticulum. A Maydl's hernia (C) has two loops in the sac (hernia-en-W). In a sliding hernia (B), a viscus forms part of the sac wall.