The Colon

By Professor Azzam K. Agha

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Diverticulosis and diverticulitis

Background Diverticula of the colon consists of out-pouchings of mucous membrane through the muscle wall of the bowel. In the colon, diverticula are found most commonly in the sigmoid and descending colon. They are unusual before the age of 40 years, but they are found in about 30% of all autopsies in the elderly. They are common in the western communities, they are extremely rare amongst people of the developing countries.
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Diverticulitis

An inflamed diverticulum may do one of three things.1. Perforate:into the general peritoneal cavity to cause peritonitis.into the pericolic tissues with formation of pericolic abscess;into adjacent structures (e.g. bladder, small bowel, vagina) forming a fistula.2. Produce chronic infection with inflammatory fibrosis resulting in obstructive symptoms – acute, chronic or acute on chronic.3. Haemorrhage. Al-Madena copy
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Clinical features

Acute diverticulitis Abdominal pain, fever, vomiting and local tenderness and guarding. A vague mass may be felt in the LIF may be due to pericolic abscess. Chronic diverticular disease Change in bowel habit, with diarrhoea alternating with constipation. Large bowel obstruction with vomiting, distension, colicky abdominal pain and constipation. Blood and mucous per rectum. Examination reveals tenderness in the LIF and there is often a thickened mass in the region of the sigmoid colon, which also may be felt per rectum. More unusual presentations are: Sudden severe rectal haemorrhage. Colovesical fistula; pneumaturia.
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Special investigations
Sigmoidoscopy Colonoscopy Barium enema: which may closely simulate an annular carcinoma. More often the oedema and thickening produce a saw-tooth narrowed segment in the sigmoid. Computed tomography CT. Differential diagnosis Neoplasm of the colon Positive biopsy is obtained by flexible sigmoidoscopy or colonoscopy.
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Treatment

Acute diverticulitis This is managed conservatively the patient is placed on fluid diet and antibiotics( metronidazole with penicillin and gentamicin or ciprofloxacin are the combinations of choice) A pericolic abscess is diagnosed by CT and may be drained percutaneously . Once the sepsis is controlled a laparotomy and resection of the diseased segment can be performed. General peritonitis Laparotomy is performed, the affected segment of colon resected and a colostomy fashioned often as a Hartmann's procedure .
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Acute obstruction The affected segment of colon is resected and the bowel brought out as an end colostomy. Chronic diverticular disease Treated conservatively the bowels are regulated by means of a lubricant laxative ( e.g. Milpar) A high roughage diet( fruit, vegetables ,wholemeal bread and bran). Colovesical fistula is treated by resection of the affected segment of the colon and bladder wall. The bowel is defunctioned by loop ileostomy to permit anastomotic healing. The ileostomy is subsequently closed.
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Angiodysplasia

Mucosal or submucosal vascular malformation most commonly in elderly. Considered to be degenerative vascular anomalies. The caecum and ascending colon are the sites most usually involved although they may be found anywhere in the small or large bowel.
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Clinical features

Usually asymptomatic Bleeding; chronic intestinal blood loss Presenting with anaemia or recurrent acute dark or bright red rectal haemorrhage Recurrent bleeding is common They account for some 5% of such emergency cases Special investigations Colonoscopy is the investigation of choice Mesenteric angiogram
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Treatment
Blood transfusion is necessary if haemorrhage is severe. Colonoscopy electrocoagulation is often curative. Resection ,usually a right hemicolectomy is sometimes required.
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Colitis

Inflammation of colon presents with diarrhoea and often lower abdominal pain and blood and mucus per rectum.The five main causes of colitis areUlcerative colitisCrohn’s colitisAntibiotic-associated colitisInfective colitisIschaemic colitis; due to mesenteric ischaemia occurring spontaneously or following ligation of inferior mesenteric artery in aortic surgery. Al-Madena copy
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Ulcerative colitis

Ulcerative colitis is an inflammatory disease of the rectum extending for variable distance proximally in the colon. Women are more often affected then men. Found in many age from infancy to the elderly but the maximum incidence is between the age of 20 and 40.
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Aetiology The aetiology of Ulcerative colitis is unknown Pathology The rectum and sigmoid colon are principally affected, but the whole colon may be involved. The wall of the colon is oedematous and fibrotic and therefore rigid with loss of the normal haustrations. Microscopically :the principal locus of the disease is mucosal crypts(crypt abscesses) these abscess break down to ulcers.
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Clinical features

Manifestation of ulcerative colitis may be fulminant, intermittent or chronic The commonest scenario is diarrhoea with blood and mucus Accompanying cramp like abdominal pains Examination reveals some tenderness in the LIF and blood on the glove of the examining finger after rectal examination In severe attacks there is fever, toxaemia , sever bleeding and risk of perforation
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Special investigations
Sigmoidoscopy: reveal oedema of the mucosa Biopsy will give confirming histological evidence of the diagnosis Colonoscopy Barium enema Examination of stool reveals pus and blood
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Differential diagnosis

Ulcerative colitis may be difficult to differentiate from other causes of diarrhoeaDifferentiation from Colonic Crohn’s disease may be particularly difficult Al-Madena copy
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Complications

Local Toxic dilatation Haemorrhage Malignant change Perianal disease: anal fissures are common ,fistula in- ano General Toxaemia Weight loss and anaemia Arthritis(including ankylosing spondylitis)and uveitis Dermatological manifestations Primary sclerosing cholangitis
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Malignant change

Have a high risk of developing carcinoma of the colon Statistics indicate that 5-12% of the patient with colitis of 20 years duration will develop malignant change Patient should therefore be offered annual or biannual colonoscopy
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Treatment
Medical treatment A high protein diet is prescribed with vitamin supplement ,iron and potassium(the last to replace electrolyte loss in the stool) Blood transfusion Diarrhoea controlled with codeine phosphate or lopermide Corticosteroid given systemically, by rectal infusion or in combination salicylates such as mesalazine or sulfasalazine (sulphonamide salicylate combination) are used to maintain a remission.
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Surgery Indications Fulminating disease not responding to medical treatment Chronic disease not responding to medical treatment Prophylaxis against malignant change with long standing disease Complications of colitis already listed The procedure usually comprises total removal of the colon and rectum with either a permanent ileostomy or an ileo-anal anastomosis.
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Crohn’s colitis is a non specific inflammatory disease of the alimentary canal with diseased segment sandwiched between normal segment, may affect any part of the alimentary tract from the mouth to the anus.AetiologyEnvironmental(cigarette smoking, urban living) and genetic .Crohn’s disease suggests an autoimmune rather than an infectious cause. Al-Madena copy
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Clinical features

Colonic crohn’s disease mimic ulcerative colitis in its clinical manifestation unlike ulcerative colitis the affected segment of colon commonly become adherent to adjacent structure with abscess formation and fistulation.Perianal inflammation with abscess and multiple fistulae in ano is also common and indeed may be the first manifestation of the disease. Al-Madena copy
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Treatment

Medical treatment Initial management is conservative. Nutritional support may be required and an elemental diet may be useful. Acute episodes are treated with steroid and immunosuppressant such as azathioprine. Parenteral nutrition may required. Infliximab a monoclonal antibody to tumor necrosis factor has been shown to be effective treatment for acute exacerbations and fistulating disease. Mild symptoms are treated with 5-aminosalicylate drugs such as sulfasalazine and mesalazine and steroids may be required. Metronidazole may also help.
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Surgical treatment Resection of extensively involved large bowel may require total excision with a permanent ileostomy. Restorative proctocolectomy and pouch formation is not performed for crohn`s disease of the immediate risks of sepsis and fistulation and the chance of recurrence.
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Tumours

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Carcinoma

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Familial Adenomatous Polyposis

This a rare disease but it is important because invariably proceed to carcinoma of the colon unless treated and accounts 5%of colon cancer It has autosomal dominant inheritance and is associated with mutation in the familial adenomatous polyposis(FAP) gene. First appear in adolescence symptom of bleeding and diarrhea at the age of 21 years and malignant change occurs between 20 and 40 years of age.
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Affected individuals usually have hypertrophy of the retinal pigment layer which is useful as a non invasive screening test. Treatment Total colectomy with excision of the rectum and formation of an ileoanal pouch.
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Hereditary non polyposis colon cancer

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Pathology

Macroscopically ,the tumours can be classified into the following groups. papilliferous malignant ulcer annular diffuse infiltrating growth colloid tumour Microscopically these are all adenocarcinomas
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Spread

Local lymphatic Blood stream Trans- coelomic
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Staging

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Clinical Features

local effects 1. Change in bowel habit. 2. Bleeding. 3.Intestinal obstruction. 4.Perforation of the tumour. The effects of secondary deposits Jaundice, Abdominal distension due to ascites or hepatomegaly.
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The general effects of malignant disease

Anemia Anorexia Loss Of Weight Tumours Of The Left Side Of The Colon lead to obstructive features in contrast, tumours of Right Side tend to be proliferative, Carcinoma of Caecum or Ascending Colon often presents with Anaemia and Loss Of Weight.
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Examination

1.Palpable mass either per abdomen or per rectum. 2.Evidence of intestinal obstruction. 3.Evidenceof spread (hepatomegaly ,ascites ,jaundice ,supraclavicular nodes). 4.Anaemia or loss of weight.
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Special investigations

1.Occult blood in the stool 2.Sigmoidscopy 3.Colonscopy 4.Barium enema 5.CT
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Differential diagnosis
1.Disease producing local symptoms 2.Diverticular disease 3.Ulcerative colitis 4.The dysenteries and other causes of diarrhoea and constipation.
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Treatment PreoperativeEnemas, oral laxatives, metronidazole and gentamicin or a cephalosporin, check hemoglobin level and blood transfusion.OperativeWide resection of the growth together with its regional lymphatics.PostoperativeAdjuvant chemotherapyFollow up cross-sectional imagingPrognosisDukes 'A usually curable with over 90% five-year survival Dukes‘ B survival about 65%.Presence of lymph node metastases give a 30% survival. Al-Madena copy
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Colonic surgery

The different colonic resection are based on the blood supply to the colon coming from superior mesenteric artery and inferior mesenteric artery. Surgery of cancer involve taking as much of lymphatic drainage as possible.
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Colostomy

When the bowel is brought to the surface and opened it is termed stoma(meaning mouth) In the case of colon such as opening termed colostomy. Stoma may be permanent e.g. when distal bowel removed or temporary when possibility of resting continuity at a future date.
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Indications 1. To divert faeces to allow healing of an anastomosis or fistula. 2. To decompress a dilated colon as a prelude resection of obstructing lesion. 3. Removal of distal colon and rectum.
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Types of colostomy
loop colostomy The colon is brought to the surface and the antimesenteric border opened. used temporarily . simple to reverse. loop ileostomy is preferred because of the better blood supply to the bowel facilitaing subsequent closure.
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End colostomy An end or terminal colostomy is fashioned by dividing the colon and bringing the proximal end to the surface. may be used as definitive procedure in someone undergoing total rectal excision . or following perforated diverticular disease.
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Double-barrelled colostomy comprises proximal and distal colon brought out adjacent to each other. useful in the treatment of sigmoid volvulus.
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Complications

Retraction Stenosis Paracolostomy hernia Prolapse Lateral space small bowel obstruction. Leakage Skin excoriation Psychological problem
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Volvulus

A twisting of a loop of bowel around its mesenteric axis . results in a combination of obstruction together with occlusion of the main vessels at the base of the involved mesentery. most commonly affect the sigmoid colon ,caecum and small intestine. But volvulus of gall bladder and stomach may occur.
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Aetiology abnormally mobile loop of intestine e.g. congenital failure of rotation of the small intestine. an abnormally loaded loop as in the pelvic colon of chronic constipation. a loop fixed at its apex by adhesions,around which it rotates. a loop of bowel with a narrow mesenteric attachment .
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Sigmoid volvulus

occurs usually in elderly constipated patients. 4 times more common in men than in women . clinical features sudden onset of colicky pain plain x-ray of abdomen shows an enormously dilated oval gas shadow on the left side which may be looped on itself to give (bent inner-tube)sign. if untreated undergoes gangrene results in death from peritonitis.
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Treatment A long soft rectal tube is passed through sigmoidscope and advance to sigmoid colon. If this method fails the volvulus is untwisted at laparotomy and the bowel decompressed via rectal tube upward from anus. If gangren has occured the affected segment is excised and the two open end are brought out as a double-barrelled colostomy which is later closed. Recurent sigmoid volvulus is an indication for elective resection of redundant sigmoid loop.
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Caecal volvulus
Associated usually with a congenital malrotation . Clinically there is an acute onset of pain in the RIF with rapid abdominal distention. X-ray of abdomen shows grossly dilated caecum which is ectopically placed ,frequently located in the left upper quadrant of the abdomen . Treatment At laparotomy the volvulus is untwisted. Right hemicolectomy is necessary if the caecum is infarcted.
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Thank you

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