Volvulus
A volulus is a twisting or axial rotation of a
portion of bowel about its mesentery. When complete it forms a closed loop of
obstruction with resultant ischaemia secondary to vascular occlusion.
Volvuli
may be primary or secondary. The primary form occurs secondary to congenital
malrotation of the gut, abnormal mesenteric attachments or congenital bands.
Examples include volvulus neonatorum, caecal and sigmoid volvulus. A secondary
volvulus, which is the more common variety, is due to actual rotation of a piece
of bowel around an acquired adhesion or stoma.
Volvulus
neonatorum is predisposed to by arrested gut rotation with a resultant narrow
mesentery of the small bowel and caecum. The symptoms are similar to arrested
rotation (vide in Ira) with repeated
vomiting, hut the onset is more catastrophic with abdominal distention and rapid
dehydration. Abdominal radiography reveals evidence of duodenal obstruction.
Laparotomy reveals a distended stomach and coils of small bowel (Fig.
58.19).
The whole midgut should he delivered to the wound and wrapped in warm, moist
towels, in order to demonstrate the volvulus which usually occurs in a clockwise
direction. The operation consists of reduction by untwisting and division of any
secondary obstructive lesions — such as the transduodenal band of Ladd.
Volvulus of the
small intestine
This may be primary or secondary and usually
occurs in the lower ileum. It may occur spontaneously in Africans, particularly
following consumption of a large volume of vegetable matter, whilst in the West
it is usually secondary to adhesions passing to the parietes or female pelvic
organs. Treatment consists of reduction of the twist and is then directed to any
underlying cause.
Caecal volvulus
This may occur as part of volvulus neonatorum
or de novo and is usually a clockwise
twist. It is more common in females and usually presents acutely with the
classic features of obstruction. At first the obstruction may be partial with
the passage of flatus and faeces. In 25 per cent of cases, examination may
reveal a palpable tympanic swelling in the midline or left side of the abdomen.
Plain radiograph may reveal a gas-filled ileum and occasionally a distended
caecum. A barium enema may be used to confirm the diagnosis with an absence of
barium in the caecum and a bird beak deformity.
At
operation the volvulus should be reduced. Sometimes this can only be achieved
after decompression of the caecum by a needle. Further management consists of
either fixation of the caecum to the right iliac fossa (caecopexy) and/or a
caecostomy. If the caecum is ischaemic or gangrenous a right hemicolectomy
should be performed.
Sigmoid
volvulus
This is rare in Europe and the USA but more
common in Eastern Europe and Africa; indeed it is the commonest cause of large
bowel obstruction in indigenous black Africans (Loefler). The predisposing
cause is summarised in Fig. 58.18. Rotation nearly always occurs in an
anticlockwise direction. Predisposing factors include high residue diet and
chronic constipation. The
symptoms are of large bowel obstruction which may initially be intermittent,
followed by the passage of large quantities of flatus and faeces. Presentation
varies in severity and acuteness, with younger patients appearing to develop the
more acute form. Abdominal distension is an early and progressive sign which may
be associated with hiccough and wretching; vomiting occurs late. Constipation is
absolute. In the elderly a more chronic form may be seen. A plain radiograph
shows massive colonic distension. The classic appearance is of a dilated loop of
bowel running diagonally across the abdomen from right to left with two fluid
levels seen, one within each loop of bowel.
Treatment
Flexible sigmoidoscopy or rigid sigmoidoscopy
and insertion of a flatus tube should be carried out to allow deflation of the
gut. Success, as long as ischaemic bowel is excluded, will provide temporary
respite allowing resuscitation and an elective procedure. Failure results in an
early laparotomy, with untwisting of the loop and per-anal decompression (Fig. 58.19).
When the bowel is viable, fixation of the sigmoid colon to the posterior
abdominal wall may be a safer manoeuvre in inexperienced hands. Resection is
preferable if it can be achieved safely. A Paul—Mikulicz procedure is a useful
procedure particularly if there is suspicion of impending gangrene (Fig. 58.20).
An alternative is a sigmoid colectomy and, where anastomosis is considered
unwise, a Hartmann’s procedure with subsequent reanastomosis.
Compound
volvulus
This is a rare condition also known as ileo-sigmoid knotting. The long pelvic mesocolon allows the ileum to twist around the sigmoid colon resulting in gangrene of either or both segments of bowel. The patient presents with acute intestinal obstruction, but distension is comparatively mild. Plain radiography reveals distended ileal loops in a distended sigmoid colon. At operation decompression, resection and anastomosis are required.