DIVERTICULOSIS
Diverticula are
acquired and are most common in the sigmoid and descending colon of middle-aged
people. Asymptomatic diverticula (diverticulosis) are present in over 50% of
people above the age of 70. Symptomatic diverticular disease supervenes in 10–25%
of cases while complicated diverticulosis (acute diverticulitis, pericolic abscess,
bleeding, perforation or stricture) is uncommon.
Pathophysiology
A life-long
refined diet with a relative deficiency of fibre is widely thought to be responsible
and the condition is rare in populations with a high dietary fibre intake, such
as in Asia, where it more often affects the right side of the colon. It is postulated
that small-volume stools require high intracolonic pressures for propulsion and
this leads to herniation of mucosa between the taeniae coli .Diverticula
consist of protrusions of mucosa covered by peritoneum. There is commonly
hypertrophy of the circular muscle coat. Inflammation is thought to result from
impaction of diverticula with faecoliths. This may resolve spontaneously or
progress to cause haemorrhage, perforation, local abscess formation, fistula
and peritonitis. Repeated attacks of inflammation lead to thickening of the
bowel wall, narrowing of the lumen and eventual obstruction.
Clinical features
Symptoms are
usually the result of associated constipation or spasm. Colicky pain is usually
suprapubic or felt in the
left iliac fossa. The sigmoid colon may be palpable and, in attacks of
diverticulitis, there is local tenderness, guarding,
rigidity (‘left-sided appendicitis’) and sometimes a palpable mass. During
these episodes there may also be diarrhoea, rectal bleeding or fever. The
differential diagnosis includes colorectal cancer, ischaemic colitis,
inflammatory bowel disease and infection. Diverticular disease is complicated
by perforation, pericolic abscess, fistula formation (usually colovesical) and
acute rectal bleeding. These complications are more common in patients who take
NSAIDs or aspirin. After one attack of diverticulitis, the recurrence rate is
around 3% per year. Over 10–30= years, perforation, obstruction or bleeding
will each affect around 5% of patients.
Investigations
These are
usually performed to exclude colorectal neoplasia. Barium enema confirms the
presence of diverticula.Strictures and fistulas may also be seen. Flexible
sigmoidoscopy is performed to exclude a coexisting neoplasm which is easily
missed radiologically. Colonoscopy requires expertise and carries a risk of perforation.
CT is used to assess complications.
Management
Diverticulosis
which is asymptomatic and discovered coincidentally requires no treatment.
Constipation can be relieved by a high-fibre diet with or without a bulking
laxative (ispaghula husk, 1–2 sachets daily) taken with plenty of fluids.
Stimulants should be avoided. Antispasmodics may sometimes help. An acute
attack of diverticulitis requires 7 days of metronidazole (400 mg 8-hourly
orally), along with either a cephalosporin or ampicillin (500 mg 6-hourly
orally). Severe cases require intravenous fluids, intravenous antibiotics,
analgesia and nasogastric suction, but randomised trials show no benefit from
acute resection compared to conservative management, and emergency surgery is
reserved for severe haemorrhage or perforation. Percutaneous drainage of acute
paracolic abscesses can be effective and avoids the need for emergency surgery.
Elective surgery is performed in patients after recovery from repeated acute
attacks of obstruction, and resection of the affected segment. with primary
anastomosis is the procedure of choice.
