Discussion
The first person to describe a case of appendiceal duplication was
Picoli in 1892. Its prevalence worldwide is 0.004% to 0.009% [3].
In a worldwide search of scientific literature, most references to
appendiceal duplication are found in case reports, indicating the rarity
of this condition. In 1936, Cave proposed a classification system based
on their anatomical location [4], and in 1963, Wallbridge revised
this classification, and the modified Cave-Wallbridge classification was
created [2]. Minor modifications were made until 1993 when Biermann
suggested the following classification, which is used today:
- Type A: Single caecum with one appendix exhibiting partial
duplication.
- Type B: Single caecum with two obviously separate appendixes.
- B1: The two appendixes arise on either side of the ileocaecal valve
in a ’bird-like’ manner.
- B2: In addition to a normal appendix arising from the caecum at the
usual side, there is also a second, usually rudimentary, appendix
arising from the caecum along the lines of the taenia at a varying
distance from the first.
- B3: The second appendix is located along the taenia of the hepatic
flexure of the colon.
- B4: The location of the second appendix is along the taenia of the
splenic flexure of the colon.
- Type C: Double caecum, each bearing its own appendix and associated
with multiple duplication anomalies of the intestinal tract as well
as the urinary tract.
- Type D: Horseshoe anomaly of the appendix [5].
Our case presented a B2 type appendiceal duplication, which is the most
common type. According to a study by Nageswaran et al. [6], there
are no associated congenital abnormalities in this type of duplication;
concealed duplication is confirmed only intraoperatively.
Type B2 duplication is the most common variation of anatomy and the most
difficult to identify. Difficulty in identification is because the
appendix that arises from the convergence of the taenia is retrocaecal
and out of sight. Moreover, if an inflamed, anteriorly placed appendix
is found, the retrocaecal space is not usually explored. It is
considered that approximately 37% of patients with duplication present
with inflammation of both appendices at the time of operation;
therefore, they may not recover postoperatively as expected. If signs of
inflammation are present along the right paracolic gutter when the
surgeon identifies an anteriorly placed appendix, careful examination of
the caecal pole and retrocaecal space should be subsequently performed.
Some extremely rare cases are described, such as ’the triple appendix’
[7], which cannot include the existing types. In 1986, Alvarado
[1] suggested a clinical diagnostic tool which considers the
patient’s signs and symptoms as well as some laboratory values. It is
used for stratifying the risk of appendicitis being present (Table 1). A
score of 5 or 6 is compatible with the diagnosis of acute appendicitis;
a score of 7 or 8 indicates probable appendicitis; and a score of 9 or
10 indicates a very probable appendicitis. The Alvarado score is
considered to have high sensitivity and low specificity; therefore, it
is useful in “catching” appendicitis. However, the score is less
effective for stratifying the risk of appendicitis in children [8].
After some years, this score was modified for patients 3-18 years old,
and the Paediatric Appendicitis Score was created and implemented.