Horseshoe appendix

Last revised by 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.

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Cases and figures

  • Figure 1: horseshoe
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