Which structure is most commonly involved in a left sliding indirect hernia?

In cases of a left sliding indirect hernia, the structure most commonly involved is the sigmoid colon. A sliding hernia typically involves a portion of the abdominal viscera that forms part of the hernia sac, meaning that the organ is adherent to the hernial sac itself. In the case of a left indirect hernia, the sigmoid colon is anatomically positioned such that it often can slide into the inguinal canal, particularly when the hernia is on the left side.

The sigmoid colon tends to be more mobile and can extend into the inguinal canal when a defect occurs in the transversalis fascia. This is in contrast to other structures like the rectum, duodenum, or cecum, which have different anatomical roles in the pelvis and abdomen, making them less likely to be involved in a left sliding indirect hernia.

The positioning and mobility of the sigmoid colon are key factors that contribute to its common involvement in these types of hernias, particularly when they are indirect and located on the left side.