Duplications
of the gastrointestinal tract are rare congenital malformations with an
incidence of 1:4000 -5000. Colonic duplications represent 3% to 20% of all
gastrointestinal duplications. Tubular hindgut duplications are associated with
genitourinary anomalies in 60% of cases. Fistulae between the duplicated colon
and the genitourinary system or perineum are present in 50% . The associated
duplication of genitourinary structures is well described.1 Malformations of the primitive hindgut (composed of the terminal
ileum, colon, and cloaca) may be particularly complex because of involvement of
the anterior and posterior portions of the cloaca. Abnormal embryogenesis in
this area may lead to duplication of the entire colon, anus, and urogenital
tract, which can be associated with spinal
dysraphism, anorectal malformation, bladder exstrophy, and
exomphalos.2
The presentation of
anorectal malformation and associated hindgut duplication is both uncommon and confusingly
classified in the literature. Two classification
systems have been put forward for tubular colonic duplication. In the first,
Yousefzadeh et al described 5 groups:
group 1: duplication with double perineal
anus;
group 2: duplication with fistula in a
female;
group 3: duplication with fistula in a male;
group 4: duplication with imperforate anus
but no fistulae;
group 5: communicating duplication with
single perineal anus.3
Emery
suggested that the anomaly occurs as a result of early embryonic twinning or
doubling of the hindgut, and that 3 types can be distinguished,
type 1: the lower genitourinary system
(derived from the anterior hindgut) is duplicated;
type 2: the lower gastrointestinal system
(derived from the posterior hindgut derivative) is duplicated;
type 3: both systems are duplicated.2
Duplication of the colon
is rare with a variable and non-specific clinical presentation, often creating
a diagnostic and therapeutic challenge. They can occur at any age, but most are
discovered during the neonatal period or infancy particularly when they are
associated with anorectal or urogenital malformation.
Colonic duplications may be asymptomatic and may remain undiagnosed for years
or diagnosed later incidentally (60%-80 %). In cases of isolated colonic duplication,
the diagnosis is invariably delayed until symptoms alert clinicians and prompt
diagnostic evaluation is undertaken. If symptomatic, they manifest by obstruction,
bleeding, constipation, and perforation. Few cases revealed by malignancy are
also reported. In cases where associated congenital anomalies are present, the duplication
is usually detected early. Female patients have a high prevalence of
rectogenital fistulas and associated duplications of internal or external
genital structures, whereas male patients have a high prevalence of
rectourinary fistulas and duplication of external genitalia. Colorectal tubular
duplications are commonly associated with vertebral anomalies as well as other
gastrointestinal and skeletal malformations regardless of the patient's sex.4
Barium
contrast enema studies are considered essential for the diagnosis of tubular
colonic duplication with opacification of 2 colons being the diagnostic sign. In
male infants who have a rectourethral fistula, improved visualization of the duplication is achieved during
cystourethrography or a retrograde urethrogram. Other imaging modalities such
as ultrasound, computed tomography, and magnetic resonance imaging may be
helpful with cystic duplications, but in instances of tubular duplication ultrasonography
computed tomography, or magnetic resonance imaging may be used in the
investigation of the commonly occurring associated anomalies. Endoscopy can
have an interesting role for both the diagnosis and the treatment.4
Indications
for surgical intervention often arise in an acute setting, in the form of
complications. The possibility of malignant degeneration within the duplication
was reported. The methods of surgical management are dependent primarily on
size, location, communication with the gastrointestinal tract, and involvement
of mesenteric vasculature. Surgery is not indicated for an uncomplicated
colonic duplication alone. It must be remembered that the treatment of this
benign lesion must aim to eliminate symptoms and prevent complications;
therefore, the surgical procedure should not be more radical than necessary. In
most cases, resection of the supernumerary colon or microcolon is impossible
because the 2 colons
often share a common blood supply and, in
most cases, there is only a single mesentery. The simplest approach is to
perform a single anastomosis between the duplications, and it was first
described by Yucesan et al. Complete resection of the duplication is possible
if both colic vascular supplies are separated, but this is exceptional (7% of
cases).5
Mortality of colonic
duplication is low: 4% to 8%. It is mainly seen in forms associated with severe
malformations or with malignant transformation. Total tubular colonic
duplication treated before the onset of complications generally have a
favorable prognosis, hence the importance of an early diagnosis.4
References
1. Craigie R. J.,
Abbaraju J. S., Ba’ath M. E., Turnock R.R., Baillie C. T., (2006). Anorectal malformation with tubular hindgut
duplication. Journal of Pediatric Surgery.
41 :E31–E34.
2. Gisquet H., et al., (2006). Colonic triplication
associated with anorectal malformation: case presentation of a rare
embryological disorder. Journal of
Pediatric Surgery. 41: E19–E23.
3. Puri,
P. Mortell, A,. (2011). Duplication of the alimentary tract. In: Newborn Surgery. 3rd ed. London: Hodder
Arnol. pp. 525-34.
4. Jellali M. A., et al., (2012). Perinatally discovered
complete tubular colonic duplication associated with anal atresia. Journal of Pediatric Surgery. 47:
E19–E23.
5. Kisa P., Kakembo D., Ozgediz D., Sekabira J., (2014)
Colonic duplication with recto-urethral fistula: Elusive diagnosis and
successful treatment in a resource-limited setting. J Ped Surg Case Reports. 2:305-308.
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