Update: We are now collecting Disclosures from all users who edit content. You will be prompted to update these when you next edit content or you can complete your disclosures at any time in your user profile. This has been reflected in an updated terms-of-use.

Horseshoe appendix

Last revised by Dr Daniel J Bell on 30 Jul 2021

A horseshoe appendix is an extremely rare variant of the vermiform appendix, in which the appendix arises from the cecum and curves back on itself to re-insert into the cecum, similar to a semicircular canal in the inner ear.

Anatomic variation of the appendix is extremely rare. In a study of 50,000 appendix surgical specimens by Donald C Collins, an American general surgeon and pathologist, appendiceal agenesis was only seen in four cases, and duplication was seen in two cases, a prevalence of 0.004%. But no cases of horseshoe appendix were seen 1. In total, eleven cases of horseshoe appendix have been reported in the English medical literature with a further four in the Chinese literature 1-9.

The appendix forms a loop with two appendiceal orifices and in theory at least acute appendicitis should be less likely as it is no longer a blind-ending tube, although at least one case has been described 2.

The first case was described as recently as 1989 by Thomas W Mesko, an American surgeon, and colleagues 1.

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Figure 1: horseshoe
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.