Background: Duplex appendix is very rare (incidence 0.004%) but has clinical relevance given the frequency of appendicectomies performed. Failure to recognise duplication can result in failure of treatment and medico-legal consequences. A review of published cases was undertaken to identify factors that may help in managing this rare condition.
Methods: All English and non-English publications were identified in PubMed, Embase and Cochrane databases. Patient demographics, intraoperative findings, anatomical details and histopathology were analysed.
Results: A total of 141 cases were identified [male/female ratio 1.4:1, median age 20 years (range foetus to 69 years)]. Duplication of the appendix ranges from branching of the appendix trunk to a fully matured appendix located elsewhere along the colon. Most can be categorised by the Cave-Wallbridge classification. There were 22 Type A, 8 Type B1, 46 Type B2 and 10 Type C cases (Cave-Wallbridge). There were six cases of horseshoe and two cases of triple appendix. Six reports gave anatomical descriptions that could not be classified by Cave-Wallbridge categories and in 11 cases there were no anatomical descriptions.
Conclusions: An anteriorly placed appendix, away from the convergence of the taenia, or a normal appendix in the presence of convincing clinical or radiological signs of appendicitis should instigate a careful examination of the caecal pole and possible exploration of the retrocaecal space for appendiceal duplication. If the patient had previous surgery for congenital abnormalities, Type B1 or Type C duplication should be considered.