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Colon
These segments may serve as a focus for volvulus in some patients, almost
always involving the markedly distended and redundant sigmoid colon
(Figs. 4.24, 4.25, 4.26). Air-fluid levels
may be seen in the remarkably dilated, obstructed sigmoid colon proximal
to the twist (Figs. 4.25 and 4.26).In patients with megaesophagus,
surgical resection with a colon transplant replacing the esophagus has
proven effective in Brazil. In patients with megacolon, the most distended
distal segments of the colon are surgically excised and an end-to-end
anastomosis performed between the relatively normal caliber proximal
colon and rectum (Fig. 4.25).
 .... ...
Fig. 4.24A-C. Sigmoid volvulus in two different
Brazilian patients with Chagas' megacolon. In patient (A) there
is the typical beak-like appearance of the barium column as it reaches
the point of volvulus in the proximal sigmoid colon. In the second patient
(B and C), the classical twisted appearance of the sigmoid
is well seen, with a slight amount of barium passing beyond the area of
volvulus in the mid-sigmoid colon. Note the considerable distention of
the entire large bowel due to underlying Chagasic aganglionosis. Volvulus
occurs in up to 10% of patients with Chagas' megacolon, almost always
involving the distended and redundant sigmoid colon. (Courtesy of Dr.
Clovis Simao, Sao Paulo).
 ... ...
Fig. 4.25 Chagas' megacolon with volvulus of the
sigmoid colon in a 59-year-old white Brazilian man who had severe abdominal
colic and distention with no passage of stool or flatus for 15 days. He
had a globus abdomen with asymmetric distention of the left side which
was painful to palpation. At operation, there was a 180° torsion of
the mesosigmoid with considerable thickening and fibrosis of the mesosigmoid.
Volvulus may often be the presenting manifestation in advanced cases of
Chagas' disease. (A) Supine AP view of the abdomen showing marked
distention of the twisted sigmoid colon which measures greater than 15
cm in diameter. (B) Erect AP view of the abdomen showing a prominent
air-fluid level within the grossly dilated, twisted sigmoid loop. (C
) A followup barium enema, performed 10 months after surgical resection
of the dilated sigmoid colon and end-to-end anastomosis of the less involved
descending colon with the rectum, shows only minimal distention of the
remaining colon and a well-functioning anastomosis. For several decades
this has been the surgical procedure of choice in patients with advanced
megacolon, with or without volvulus. (Courtesy of Dr. Clovis Simao).
 ... ...
Fig. 4.26 Volvulus of the sigmoid colon with
perforation in a Brazilian adult with Chagas' megacolon. Supine AP view
of the abdomen (A) shows a massive amount of feces within a grossly
dilated and twisted sigmoid colon. Erect AP view (B) shows a
prominent air-fluid level within the distended, fecal-laden sigmoid
colon. An AP view of the abdomen taken some time later (C) shows
free air within the abdomen following perforation of the markedly distended
sigmoid colon after an unsuccessful attempt at decompression and evacuation
of feces. (Courtesy of Dr. Clovis Simao).
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