Internal Hernias Involving the Sigmoid Mesocolon
CAPT. J. ROBERT BENSON,** MC, USA, CAPT. DUNCAN A. KILLEN,*§
From the Department of Surgery, Walter Reed General Hospital,
WRAMC, Washington 12, D. C.
INTERNAL hernias account for only a
small percentage of all instances of intesti-
nal obstruction. Hernias which result from
defects, or abnormalities of the sigmoid
mesocolon are among the rarer types of
internal hernia. Management of a patient
who presented with intestinal obstruction
due to a previously unreported variant of
such internal hernias prompted this report.
This 42-year-old woman was admitted to De-
Witt Army Hospital on September 4, 1962, with
a four day history of intermittent, cramping pain
in the lower abdomen. This was associated with
obstipation and slight abdominal distention, but
without nausea or vomiting. There was no history
of previous similar episodes of abdominal pain
or prior abdominal operation.
Physical examination revealed the patient to
be well developed, well nourished, and in no
distress. Temperature was 370 C., pulse 88, and
blood pressure 120/88. The abdomen was slightly
distended, but soft without tenderness, spasm, or
masses. No external hernia was present. Pelvic
examination was normal. The remainder of the
physical examination was unremarkable.
Laboratory examination revealed a hematocrit
of 44 per cent and a white blood cell count of
8,000 (following hydration). Roentgenogram of
the chest was normal. Flat and upright roentgeno-
grams of the abdomen showed slight distention
of two loops of small bowel with air-fluid levels.
There was a small amount of colonic gas present.
The patient was given nothing by mouth and
parenteral fluids were administered. There was
subsidence of all symptoms and persistence of a
good appetite. Bowel sounds were normal and
abdominal examination remained essentially un-
changed. X-ray of barium enema of the colon was
*Submitted for publication March 12, 1963.
Resident, General Surgery Service.
Surgical Service, DeWitt Army Hospital,
Fort Belvoir, Virginia.
normal. Despite nasogastric suction, repeated ab-
dominal roentgenograms showed progressive
crease of the small bowel distention.
September 10, 1962. At operation, the colon and
terminal ileum were found collapsed. Proximal
small bowel was
inches from the ileocecal valve, the ileum entered
the ring of an internal hernia
hernial ring was oval, 2 cm. in diameter, and
situated in the left leaf of the mesosigmoid. The
ileum passed anterior to the sigmoid colon to
enter the defect where the small bowel was en-
carcerated. The ring of the sac was incised, re-
leasing a 15 cm. segment of viable ileum. Exami-
revealed that the ring of the sac was formed by
the left peritoneal leaf of the mesosigmoid, im-
hernial sac itself was contained within the meso-
sigmoid and extended caudally into the presacral
space, posterior to and to the left of the upper
rectum. The hernia did not involve the sciatic
foramen. The hernial defect was repaired with
interrupted silk sutures. An incidental appendec-
tomy was performed. No other intra-abdominal
abnormality was found.
The postoperative course was uneventful. The
September 29, 1962. Her subsequent course has
to the sigmoid
Internal hernias account for between 1
and 3 per cent of all instances of intestinal
obstruction.2'7 The more frequently en-
countered internal hernias are those related
to the paraduodenal fossae, the paracecal
fossae, defects of the small bowel mesen-
foramen of Winslow. Hernias involving the
sigmoid mesocolon account for only about
5 per cent of all internal hernias,4 there
INTERNAL HERNIAS INVOLVING SIGMOID MESOCOLON
being only 33 cases reported prior to this
presentation (Table 1).
Internal hernias involving the sigmoid
mesocolon may be divided into three dis-
tinct categories. These may be designated
as 1) intersigmoid; 2) transmesosigmoid;
and 3) intramesosigmoid hernias, of which
overwhelming majority of cases.
Intersigmoid Hernia. The title of inter-
sigmoid hernia has been used to designate
herniation into a congenital fossa, the inter-
sigmoid fossa, situated at the attachment
of the lateral aspect of the sigmoid meso-
during the fusion of the left periotoneal
surface of the sigmoid mesentery with the
parietal peritoneum of the posterior ab-
dominal wall, forming the so-called fascial
fusion line of Toldt. The fossa is said to
be present in from 50 to 75 per cent of all
bodies.5 When large enough to be associ-
ated with herniation, a retroperitoneal sac
is present with
sigmoid fossa. The mesosigmoid and
vessels are anterior to the hernia; the left
ureter, psoas muscle, and iliac vessels lie
Thirty cases of intersigmoid hernias have
been reported from 1885 to the present
time. Small intestine was encarcerated in
an enlarged intersigmoid fossa in all cases
at the inter-
T'ABsLE 1. Interntal Hernias Invoklziii
*Case of present report.
except two, in which the sigmoid colon
itself was the encarcerated viscus. Of the
27 cases which came to operation, only 14
survived. Three cases were autopsy find-
ings; and in one of these, the hernia was
an incidental finding.
Transmesosigmoid Hernia. The title of
transmesosigmoid hernia has been used to
describe incarceration of intestinal loops
through an isolated, oval defect in the sig-
moid mesocolon (Fig. lb). No hernial sac
is present in this condition. The develop-
mental origin of this defect is uncertain,
but is probably analogous to similar defects
in the mesentery of the terminal ileum, as
described by Treves.'2
There have been only three cases of this
condition reported,1' 9,13 all of which pre-
sented with acute intestinal obstruction.
The two patients who underwent opera-
tion recovered. The third case was diag-
FIG. 1. Internal hernias involving the sigmoid mesocolon.
a. Intersigmoid hernia; b. Transmesosigmoid
c. Intramesosigmoid hernia (X = site of intersigmoid fossa).
nosed at autopsy. In twvo cases, terminal
ileum was caught in the defect, and redun-
dant sigmoid colon was encarcerated in the
Intramesosigmoid Hernia. The case re-
port presented in this paper would seem
to form a third variant of internal hernias
involving the sigmoid mesocolon (Fig. lc).
Again, an apparently congenital, oval de-
fect was found in the lateral peritoneal
surface of the mesocolon. However, this
defect was adjacent to the colon itself,
normal peritoneal reflection (fascial fusion
line) was present at the base of the meso-
colon. The location of the hernial orifice in
juxtaposition to the sigmoid colon is similar
to the reported cases of transmesosigmoid
hernias; however, the hernial defect in-
volved only one leaf (the left) of the meso-
colon, the right leaf being intact. The
of the hernial
mesosigmoid suggests the designation of
"intramesosigmoid hernia." Report of no
similar case could be found by review of
the English literature.
The preoperative diagnosis of internal
hernia is unusual, and it is even more dif-
herniation present. However, the diagnosis
should be considered in the absence of
previous abdominal operation and external
hernia. An important facet of the present
case, and the one previously discussed by
Harrison and Creech,5 was the absence of
signs of peritoneal irritation in the pres-
ence of an inflamed loop of encarcerated
bowel. This is apparently explained by the
retroperitoneal and pelvic location of the
The basic tenet of management of acute
intestinal obstruction caused by any of
the intestinal hernias described is prompt
laparotomy. Following reduction
encarcerated viscus, the hernial orifice is
obliterated by suture. The results of treat-
ment by early operation are good.
BENSON AND KILLEN
sac within the
A case of intramesosigmoid hernia
reported. This is a type of internal hernia
contained within the sigmoid mesocolon,
and had not previously been recorded. The
mesentery of the sigmoid colon are re-
viewed, classified, and discussed.
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