To briefly summarize the embryology of the normal appendix, during the
fifth foetal week, a bud at the junction of the small and large bowel
develops and undergoes rapid growth into a pouch. The proximal end of
this pouch starts growing differentially to give rise to the caecum. The
appendix first appears at the eighth week of gestation as an outpouching
of the caecum. Then, it gradually rotates to a more medial location
following the respective rotation of the gut, which results in the
fixation of the caecum in the right lower quadrant [9]. The normal
embryogenesis of the appendix is well-known. However, there are no data
regarding the causes of its duplication, and malrotation does not seem
to be responsible for the pathophysiology of the condition. Cave [4]
tried to explain the pathogenesis of duplication. To achieve this, he
concluded with two theories: a) the persistence of a transient
embryological structure and b) incidental appendiceal duplicity to a
more general affection of the primitive midgut. However, even though
Cave’s theories may explain some types of duplication, they are
inadequate to explain all types reported.
It is difficult to diagnose double appendixes using routine imaging
examinations. Abdominal ultrasound and computed tomography (CT) are the
main methods available. However, these image examinations – mainly the
CT scan – are usually not included in the routine workup of otherwise
healthy patients with pain in the right iliac fossa. In cases where the
patient is a child, the situation is even more challenging since a CT is
avoided as the initial imaging choice due to the risk of radiation
exposure. The CT has been reported to identify duplication of the
appendix, especially in cases where both appendixes are significantly
inflamed [10].