Colorectal disorders

Published on 11/04/2015 by admin

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9 Colorectal disorders

Ulcerative colitis

This is a chronic, inflammatory disease which involves the whole or part of the colon. Colitis may be caused by a number of different conditions, including infection (Boxes 9.1 and 9.2). Ulcerative colitis is common in the UK, North America and Scandinavia, with a slightly increased incidence of familial occurrence. The inflammation is confined to the mucosa and nearly always involves the rectum (Fig. 9.1).

Box 9.1 Non-infective causes of colitis/proctitis

Ulcerative colitis

Crohn’s disease

Ischaemic colitis

Irradiation colitis

Figure 9.1 A patient with ulcerative colitis.

Aetiology is unknown but immunological, dietary and genetic factors and transmissible agents may be involved. The inflammatory changes are most marked in the rectum and spread to a varying degree proximally into the colon. The disease does not extend proximal to the ileocaecal valve. The histological features are shown in Box 9.3.

Box 9.3 Histological features of ulcerative colitis

Lymphocyte and neutrophil infiltration of lamina propria

Crypt abscess formation

Goblet cell depletion

Destruction of surface epithelium (ulceration)

Dysplasia (serious sign – precedes malignancy)

Clinical features

• Rectal bleeding

• Abdominal pain

• Weight loss.

Advanced cases may demonstrate malnutrition and abdominal distension. Extra-abdominal manifestations include erythema nodosum, pyoderma gangrenosum, arthritis, uveitis and sclerosing cholangitis.

Physical findings in mild cases are few or absent. Severe cases demonstrate weight loss, anaemia, dehydration, abdominal distension and tenderness.

Complications of ulcerative colitis

Toxic megacolon

Severe inflammation may cause the transverse colon, in particular, to dilate. There is severe systemic disturbance including toxaemia, anaemia, water and electrolyte depletion and progressive distension. Perforation of the colon, which has a high mortality, may ensue.

Colorectal cancer (p. 157)

The risk increases in patients who have had total colitis, approaching 20% risk at 20 years of the disease. Dysplastic change in the glands is thought to be a marker for the risk of malignant change. Regular colonoscopy is required yearly in longstanding colitis to exclude development of carcinoma.

Investigations

• Rigid sigmoidoscopy

• Colonoscopy

• Stool cultures to exclude infective causes of colitis

• Barium enema, rare now in UK

• FBC, U&E, LFTs

• AXR in the acute situation to watch for development of toxic megacolon.

Treatment

Medical

The majority of patients have limited disease and are managed by a combination of prednisolone suppositories and a 5-ASA preparation, e.g. mesalazine. Chronic severe cases may respond to immunosuppressive therapy. Acute severe disease causes severe systemic illness and requires admission to hospital. Treatment of acute colitis requires:

• parenteral steroids

• blood transfusion

• intravenous fluid replacement

• daily AXR (risk of colon perforation high as caecal diameter approaches 10 cm)

• close collaboration between gastroenterologist and surgeon.

Surgical

Indications for surgery are listed in Box 9.4.

Box 9.4 Indications for surgery in ulcerative colitis

Severe exacerbations of colitis

Toxic colon/acute dilatation

Chronic colitis refractory to medical treatment

Development of premalignant changes (dysplasia) in colon/rectum

Development of carcinoma of colon/rectum

In acutely ill patients who have not responded to maximal medical therapy, the best operation is subtotal colectomy with end-ileostomy, leaving the rectum in situ. In elective cases, the conventional treatment is proctocolectomy (i.e. removal of colon and rectum) with permanent ileostomy. In younger patients, restorative proctocolectomy with ileal pouch to prevent lifelong ileostomy is often performed. In elderly patients, ileorectal anastomosis or continent ileostomy are alternatives. Ileostomy complications include hernia, prolapse, renal calculi, electrolytic imbalance, psychological/sexual problems and parastomal dermatitis.

Crohn’s disease of the colon (see p. 129)

Crohn’s disease may involve the large bowel, either in isolation or in combination with small bowel disease. Symptoms include diarrhoea, indistinguishable from ulcerative colitis. In addition, perianal problems (perianal abscess, fissure and fistula) may occur (see later).

Clinical findings

A high incidence of anal lesions is seen. Sigmoidoscopy and biopsy or colonoscopy confirm the histological diagnosis. Colonoscopy will demonstrate segmental disease and the presence of fissures and fistulas in the bowel. Medical treatment is similar to ulcerative colitis but colectomy may be required, particularly for bowel obstruction; pouch or continent ileostomy is not performed due to risk of anastomotic breakdown and fistulas.

Surgical procedures for colitis

See Figure 9.2a, b and c.

Figure 9.2 (a) Colectomy and ileorectal anastomosis. (b) The continent ileostomy. (c) Ileal pouch with ileo-anal anastomosis.

Ischaemic colitis

This is uncommon under the age of 50 years. It usually occurs at the splenic flexure at the junction of the mid- and hind-gut arterial supply. Patients often present with acute left-sided abdominal pain and dark red rectal bleeding. Clinical features include fever, hypotension and abdominal distension. Diagnosis is confirmed by colonoscopy and biopsy. Spontaneous resolution is the rule. Anticoagulation may be beneficial (therapeutic-dose LMWH). Occasionally, surgery is required for progressive ischaemia and gangrene. Late complications include stricture.

Diverticular disease

The main manifestations of diverticular disease are listed in Box 9.5.

Box 9.5 Manifestations of diverticular disease

Chronic LIF pain, altered bowel habit

Acute diverticulitis (p. 91)

Diverticular abscess or mass

Rectal bleeding

Perforation causing acute peritonitis

Fistula formation (into bladder or vagina)

Epidemiology and pathology

Diverticular disease comprises outpouching of the mucosa through the bowel wall associated with an increased intraluminal pressure. The most common site is the sigmoid colon. Diverticular disease is rare under the age of 35 years, but reaches a prevalence of 50% among those in their eighth or ninth decade. It is common in Western countries and rare in China, India and Africa. Lack of roughage in the diet appears to be the most common risk factor.

Inspissated faeces may accumulate within the narrow neck of a diverticulum and inflammation of the sac may lead to perforation, leading to a diverticular abscess or peritonitis. Fistula formation may occur to adjacent organs, for example the bladder. Diverticular disease may be asymptomatic. Acute diverticulitis presents as lower abdominal pain localising to the left iliac fossa. Changes in bowel habit and abdominal distension may occur.

Chronic diverticular disease may cause lower abdominal pain, alternating constipation and diarrhoea with excessive flatus. Findings in the chronic case may be minimal. Acute diverticulitis (p. 91) has been called left-sided appendicitis in terms of physical findings. A perforated diverticulum may cause generalised peritonitis, or become walled by omentum and small bowel to form an abscess surrounded by inflamed tissues: this is termed a diverticular mass.

Investigations

Full blood count, colonoscopy (electively) and CT scanning are the usual methods of confirming the diagnosis. Coexistent carcinoma of the colon is not uncommon, and it may be difficult to distinguish a diverticular mass from a cancer.

Treatment

• Uncomplicated diverticular disease may respond to bulking agents (e.g. ispaghula). If pain or complications occur, resection of the affected segment may be considered. Barium enema assists assessment of the extent of bowel to be resected (Fig. 9.3)

• Acute diverticulitis requires bed rest, fluids only, and antibiotics (e.g. cefuroxime, metronidazole). Perforated diverticulum requires laparotomy and resection of the perforated bowel. Rejoining the bowel is risky in the presence of peritonitis and the proximal bowel is usually brought out as an end colostomy (Hartmann’s procedure: resection of the sigmoid colon, oversewing of the rectal stump and LIF end colostomy). This may be performed laparoscopically

• Haemorrhage – rectal bleeding due to diverticular haemorrhage can be profuse and require significant transfusion. The distinction between upper and lower GI bleeding can be difficult (Table 9.1) and OGD is usually required to exclude UGIH. Most diverticular bleeds stop spontaneously. Urgent colonoscopy and angiography ± embolisation may be required. If haemorrhage is life-threatening, a colectomy with ileostomy may be considered.

Figure 9.3 Barium enema in a patient with diverticular disease.

Table 9.1 Upper versus lower gastrointestinal bleeds

	Upper gastrointestinal	Colonic
Haematemesis	Common	Never
Stool	Melaena, or dark blood with clots, fresh blood for a brisk major bleed	Bright red bleeding or dark red with clots
Plasma urea	Elevated (due to partial digestion of blood)	Normal
Pain	No	No

Diverticular mass/abscess/fistula (Table 9.2)

The surgery required for such problems can be complex and difficult. Antibiotics may help reduce some of the inflammation preoperatively. Simple defunctioning ileostomy may be very helpful. Exclusion of cancer is mandatory.

Table 9.2 Hinchey grading system: classification of perforations of colon due to diverticular disease (and current management strategy)

Grade	Definition	Treatment
I	Localised abscess	Medical ± radiological
II	Pelvic abscess	Medical + radiological
III	Purulent peritonitis	Surgical (laparoscopic or open)
IV	Faeculent peritonitis	Surgical (open)

Volvulus

This is a loop of bowel twisted around its mesenteric axis, resulting in partial or complete obstruction. Gangrene may occur due to occlusion of the arteries at the base of the mesentery. The sigmoid and caecum may be involved, the former being more common.

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