The Turkish Journal of Gastroenterology
2007, Volume 18, No 4, Page(s) 261-264
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|Congenital pouch colon: Is it really a rare pathology?
|Cüneyt ATABEK1, Suzi DEMİRBAĞ1, İlhami SÜRER1, Murat KOCAOĞLU2, Önder ÖNGÜRÜ3,
Bahadır ÇALIŞKAN1, Haluk ÖZTÜRK1
|Departments of 1Pediatric Surgery, 2Radiology and 3Pathology, Gülhane Military Medical Academy, Ankara
|Keywords: Congenital pouch colon, anorectal malformation,
congenital short colon, constipation.
Congenital pouch colon is a condition of a shortened and pouchlike
dilated colon and it is usually associated with an anorectal
malformation. The pathogenesis and embryology of congenital
pouch colon are not well understood, but dietary, environmental
factors and familial inheritance may be contributing factors
in this pathology. Most of the cases in the literature have been
reported from India. This increased regional incidence may be
attributed to the lack of awareness of this pathology or its mislabeling
rather than regional distribution. Congenital pouch colon
is classified into four types based on the length of the abnormal
colon. A variable dilatation of the rectum and sigmoid is
always present in anorectal malformation. However, there is no
clear definition of a limit for the dilatation of the rectum and
sigmoid observed in anorectal malformation. Furthermore,
many surgeons do not routinely take a biopsy from a dilated rectum
or sigmoid during a colostomy procedure in anorectal malformation
cases. For these reasons, type IV congenital pouch colon
can be easily underdiagnosed. Surgical treatment options in
type IV congenital pouch colon include resection of the affected
sites of the colon or excisional tapering coloplasty. In the undiagnosed
cases, congenital pouch colon results in severe constipation
and overflow incontinence. We herein report two additional
new cases of type IV congenital pouch colon.
Congenital pouch colon (CPC) is a rare condition
in which there is a short, pouch-like dilated colon
and it is usually associated with an anorectal malformation
(ARM) (1-3). The pathogenesis and
embryology of CPC are not well understood, but
dietary, environmental factors and familial inheritance
may be contributing factors in this pathology
(2). CPC is classified into four types based on
the length of the abnormal colon (4):
Type I: Normal colon is absent and the ileum
opens directly into the colonic pouch.
Type II: The ileum opens into a short segment of
cecum which then opens into the colonic pouch.
Type III: Presence of a significant amount of normal
colon between the ileum and the colonic pouch.
Type IV: Presence of nearly normal colon with
only terminal portion of the colon (rectum and varying
portions of the sigmoid) converted into a pouch.
Histopathological examination of CPC reveals mucosal
and submucosal inflammation, focal or generalized thinning and disorganization of muscle layer
and presence of immature ganglion cells and
decreased number of mature ganglion cells with
neuronal dysplasia (5). The majority of patients
with CPC are reported from India when compared
to other parts of the world (1,2,4-7). Although
types I and II CPC were more common in large series
from India (1,2,4-7), recently the number of
patients with type IV CPC has been increasing (8).
Hence, is type IV CPC really a rare condition or is
it ignored? Here, we report two cases of type IV
CPC and discuss the diagnosis and treatment of
A one-day-old female presented with rectovestibular
fistula. The patient was evaluated for associated
anomalies after physical examination. The
patient's length and weight were 49 cm and 3.3 kg,
respectively. Blood and urine analysis were normal.
Plain abdominal X-ray revealed dilated bowel
loops. Chest and spinal X-rays, abdominal and spinal
ultrasonography (US) and echocardiography
were performed. Bilateral hydroureteronephrosis
was diagnosed on US examination and bilateral
grade-4 vesicoureteral reflux (VUR) was also detected
at voiding cystourethrogram (VCUG). Laparotomy
was performed through a left lower quadrant
oblique incision and type IV CPC was observed.
The dilated antimesenteric portion of the
sigmoid colon and rectum above the peritoneal reflection
level was resected. Tapering coloplasty was
completed by closure of the antimesenteric side of
the colon over a number 12 anal dilator, and sigmoid
diverting colostomy was done. Biopsy specimens
revealed mild lymphoid hyperplasia and
marked fibrosis in the submucosa. Inflammation
with minimal congestion was noted in the submucosa
and mucosa. Thinning of the outer muscle layer
with a normal inner layer and a decreased
number of mature ganglion cells were also noted
(Figures 1,2). During posterior sagittal anorectoplasty
procedure at the age of six months, the rectum
was mobilized from the vestibule, excisional
tapering of the rectum below the peritoneal reflection
level was completed and the rectum was located
within the sphincter mechanism. Colostomy
was closed at eight months of age. The postoperative
period was uneventful. Barium enema was repeated
one year later and the diameter of the rectosigmoid
colon was observed to be normal. The
child currently has voluntary bowel movements 2-
3 times a day and has no soiling.
A two-day-old male presented with an anocutaneous
fistula ending at the scrotum; orifice of the fistula
was quite narrow and was not suitable for dilatation.
The patient was examined for possible
associated anomalies. The weight and length of
the patient were 2.5 kg and 34 cm, respectively.
Blood and urine analysis, chest and spinal X-rays
and echocardiographic examination of the patient
were normal. Abdominal X-ray revealed dilated
bowel loops. Left hydroureteronephrosis was diagnosed
on US examination and left-sided grade-3
VUR was detected at VCUG. Because of the associated
VUR, low birth weight and fistula dilatation
problem, we decided to perform a sigmoid colostomy.
Laparotomy was performed through a left
lower quadrant oblique incision, revealing a greatly
dilated rectum and a dilated portion of the
sigmoid colon. The dilatation of the sigmoid colon
was localized to its lower end and transition to normal sigmoid colon was abrupt. Type IV CPC
was suspected; sigmoid colon biopsy and sigmoid
diverting colostomy were performed. Contrast
study of the colon after colostomy opening revealed
the diagnosis of type IV CPC (Figure 3). Histopathological
examination of the biopsy revealed
mucosal and submucosal inflammation, thinned
outer muscular layer and decreased number of
mature ganglion cells. Posterior sagittal anorectoplasty
was performed at six months of age and
at this stage excisional tapering coloplasty of the
rectum and of the distal sigmoid colon was performed
over a 13 anal dilator. Colostomy was closed
six weeks later. The child has voluntary bowel movements
twice a day and no soiling.
A total of 360 CPC cases have been reported from
India, versus only 7 cases from Canada, 6 from Turkey and a few from Iran, China, Japan, United
States and Europe (2,9). Types I, II and III CPC
are usually diagnosed during the preoperative
evaluation period in ARMs and there are typically
large air fluid levels in plain abdominal X-ray (1-
2,4-7). However, type IV CPC does not have this
appearance on plain X-ray and is diagnosed at colostomy
opening (7,8,10-12). A variable dilatation
of the rectum and sigmoid is always present in
ARMs. However, there is no clear definition of a limit
for the dilatation of the rectum and sigmoid in
ARMs (8). Furthermore, many surgeons do not routinely
take a biopsy from a dilated rectum or sigmoid
during a colostomy procedure in ARM cases.
Many surgeons also prefer a right upper quadrant
transverse colostomy instead of a traditional sigmoid
diverting colostomy, without exploration of
the remaining colon (13). For these reasons, type
IV CPC can be easily underdiagnosed. In our cases,
we diagnosed type IV CPC based on surgical
Megarectosigmoid is also common after surgical
correction in certain types of ARMs - rectovestibular
fistula, perineal fistula, rectal atresia, and rectobulbar
fistula, and usually occurs if fecal impaction
is not prevented and treated by laxatives (13-
16). This condition is more common and usually
develops after the age of three if patients with
ARMs are not followed up appropriately for the
earlier recognition and treatment of constipation.
In severe forms of this condition, resection of megarectosigmoid
is required to reduce the amount of
laxatives (13-16). In contrast, type IV CPC is a
congenital malformation, is not preventable and
surgery is indicated. However, it is still a fact that
type IV CPC should be considered in the differential
diagnosis of megarectosigmoid in ARMs at any
age (7). The discrimination between these two entities
again depends on surgical and histopathological
In the histopathological examination of the CPC,
the most frequently observed abnormalities are
acute and chronic inflammation of the mucosa and
submucosa, focal or generalized thinning of muscle
layers, especially of the outer muscle coat, disorganized
muscle layers, and a decreased number of
mature ganglion cells. Neuronal hyperplasia and
hypertrophy in nerve plexuses are also observed
at the affected segment of the colon (5). We did not
perform routine immunohistochemical staining in
this report and therefore we could not comment on
the presence or absence of neuronal dysplasia. However, we also think that neuronal intestinal
dysplasia must be investigated in type IV CPC for
correlation with postoperative outcome.
The incidence of associated cardiac, vertebral and
genitourinary anomalies is very high in CPC, so
evaluation of the genitourinary tract, skeletal system
and cardiovascular system for associated anomalies
is very important (1,2,5,10). In the systemic
evaluation of our patients, both had VUR.
Surgical treatment options in type IV CPC include
resection of the affected sites of the colon or excisional
tapering coloplasty (2). Reconstruction of the
sac-like colon to form a tube to preserve colonic absorptive
function is essential (16). For that reason,
we prefer excisional tapering coloplasty.
In conclusion, in ARM cases, when the sigmoid colon
or rectum is not explored appropriately, associated
type IV CPC may be underdiagnosed. However,
if type IV CPC is specifically searched, the
incidence would perhaps be higher than expected.
It is important for gastroenterologists and pediatric
clinicians to be aware of the features of this
condition to allow for proper diagnostic evaluation
and surgical management.
The authors thank Mehmet Elicevik, MD and
Sachin Vaikunth, MD for their kind interest.
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