Volvulus of Colon

DEFINITION
Rotation of the gut on its own mesenteric attachment, producing either partial and complete obstruction.
Caecal and sigmoid
Also occurs in transverse but very rarely.
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EPIDEMIOLOGY

~10% of colonic obstructions
A reasonably common surgical emergency.
- much higher in non-Westernized countries; dietary
Mean age 50 sigmoid
Caecal ~younger 30-60, F>M

Risk Factors

Excessively mobile colon;
- anything that stretches the colon
Chronic constipation and lack of exercise
Typically elderly rest home patients with chronic constipation and relatively atonic colons

High-fibre diet in non-West
Megacolon of any cause
- e.g. hypothyroidism, Parkinson, Hirschsprung, Chagas, pregnancy
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AETIOLOGY

As above.
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BIOLOGICAL BEHAVIOUR

Pathophysiology
: Sigmoid (~75%)

Disproportionately long colon compared to mesenteric base
Allows sigmoid to rotate, usually counterclockwise 15-25cm from anal verge
- degree of torsion varies from 180 (35%) to 360 (50%) to 540 (10%)
Obstructs and strangulates
But rarely perforates due to thickened sigmoid

Pathophysiology : Caecal (~25%)

Redundant R colonic mesentery.
Maybe 10% of the population have a cecum sufficiently mobile to tort but far fewer do
- improper fusion of cecal / ascending colonic mesenteries
- restriction of bowel at a fixed point, e.g. adhesions, congenital bands, obstruction lesions
--> most do a 180 to 360o twist around the mesenteric pedicle of the ileocolic artery.
May be precipitated by colonoscopy, pregnancy, air-flight.

Often associated with vascular compromise

Cecal Bascule
A variant of cecal volvulus where the cecum folds anteromedial, causing a flap-valve occlusion.

Transverse (rare)
Middle age, 2:1 F/M
Treat as for cecal volvulus; may need extended R hemi.

Splenic Flexure Volvulus
Least common site; <1%
Congenital absence of gastrocolic, phrenocolic and splenocolic ligaments
- or iatrogenic loss of those.
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MANIFESTATIONS

Sigmoid

Obstruction
Often develops slowly and recurrent.
Distension, colicky pain and reduced flatus / stool (partial vs complete)
Nausea, vomiting, dehydration and obstipation are usually late features

Strangulation
Acute and less common presentation
Pain, progressing to sepsis

Caecal
SBO presentation
Often atypical and subtle.

Signs

Distended tympanic abdo with diffuse tenderness.
DRE: empty rectum.
Peritoneal signs and fever indicate possible strangulation


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INVESTIGATIONS

Sigmoid

XR
Large twisted sigmoid loop like a bent inner tube
CT
- loop and whirl sign; grossly distended sigmoid
Gastrografin enema
- bird beak; old school

Caecal

XR:

Absent caecal shadow and grossly distended loop - flipped up and left into epigastrium or left hypochondrium; concavity points to RLQ.
'Coffee bean' appearance.
Single air fluid level in loop
May be atypical and subtle.
CT
Shows the volvulus; also whirl sign, bird's beak

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MANAGEMENT

Sigmoid

Acute

Pass a rigid sigmoidosope to the site of the twist (us. 15cm)
- may need flex sig if higher twist.
Lubricate a large rectal tube (36F) and pass it into the twist
- leave it 2-3d
80% success rate
2% perforate, 2% mortality
But >50% recur
--> schedule elective surgery, preferably at same admission.
If fails then colonoscopic decompression

Operative : Acute
Much higher mortality than decompression and elective surgery
Generally only if strangulated (or if - rare - colonoscopic decompression fails)
- needs to twist 180 to obstruct and 360 to strangulate.
Modified lithotomy position.
Sigmoid resection, either with anastomosis or as a Hartmann's procedure.
- depending on patient physiology, comorbidities and disease factors
- favour primary anastomosis unless patient cold, unstable, acidotic or bowel uncertain viability
- if unstable, with metabolic and hemodynamic instability, may be able to leave in discontinuity with a view to second look and possible anastomosis.
If gangrenous, resect without untwisting to present flood of mediators and bacteria

Operative : Elective
To prevent recurrent in re-presenters.
- half will not represent, the other half may keep coming back
--> most surgeons offer resection after a second episode.
Small transverse incision, deliver loop and resect.
Sigmoidopexy is an option; good morbidity but recurrence rate up to 30%

image

Caecal

Uncommon
Requires surgery; high risk of bowel ischaemia
- colonoscopy reported by not recommended.
Detort caecum, de-rotate anticlockwise.

R hemicolectomy
if doubtful viability.
If uncertain, do it anyway or plan a second look.
If viable, R hemi is still a safe option, safe with a very low mortality
Usually can do a primary anastomosis.

Cecopexy
is the alternative option.
- decompress by milking toward a rectal tube.
--> sutures hold poorly in a distended bowel wall.
--> then suture entire caecal length to the lateral abdo wall using nonabsorbable sutures and with big seromuscular bites of bowel and deep abdo wall bites.
- problem is recurrence of 15%, so perhaps better to just resect.

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REFERENCES