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SMALL INTESTINE (CROHN'S DISEASE (CLINICAL FEATURES (INTESTINAL…
SMALL INTESTINE
CROHN'S DISEASE
non-specific inflammatory diseaseof the alimentary canal, with diseased segments sandwiched between normal segments (ie it is discontinuous)
may affect any part of alimentary tract from mouth to anus
AETIOLOGY
Environmental - smoking, urban living
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granulomas on histology suggested infection by a mycobacterium species = mycobacterium avium ssp paratuberculosis
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PATHOLOGY
DISTRIBUTION
the small bowel is affected in two thirds of cases with the lower ileum being the most common site, although the disease may affect any part of the alimentary canal from the buccal mucosa to the anal verge
1/3rd of pts with ileal diseae also have rectal or colonic manifestations
MACROSCOPIC APPEARANCE
in the acute stage the bowel is bright red and swollen; mucosal ulceration and intervening oedema result in a cobblestone appearance of the mucous membrane
the wall of intestine is greatly thickened as is the adjacent mesentery and the regional lymph nodes are enlarged
mesenteric fat advances over the serosal surface in affected segments
there may be skip areas of normal intestine between involved segments
fistulas may occur into adjacent viscera
MICROSCOPIC APPEARANCE
there is fibrosis, lymphoedema and a chronic inflammatory infiltrate through the whole thickness of the bowel with non-caseating foci of epithelioid and giant cells.
Ulceration is present, with characteristic fissuring ulcers extending deep through the mucosa
these may extend through the mucosa
these may extend through the bowel wall to form abscesses or fistulas into adjacent viscera
CLINICAL FEATURES
INTESTINAL OBSTRUCTION - following inflammatory exacerbations, fibrosis of the intestinal wall occurs, leaving stenotic segments which result in intestinal obstruction. obstruction may also follow an intraperitoneal abscess
DIARRHOEA - may be due to inflammation and mucosal ulceration, colonic or rectal involvement, bacterial overgrowth in obstructed segments and malabsorption secondary to either disease or short bowel following previous surgery. mucosal ulceration causes diarrhoea with positive occult blood and anaemia
ACUTE CROHN'S DISEASE - crohn's disease may present like appendicitis with acute abdo pain, usually in the RIF and vomiting. Rarely there is perforation of the bowel or acute haemorrhage. Unlike appendicitis, the hx is usually of several days or weeks and ix may reveal anaemia or other features of Crohn's disease may be present
FISTULA FORMATION - fistulas may develop, penetrating adjacent loops of gut or the bladder or they may be perianal. external faecal fistulas may follow operative intervention
occurs at any age, particularly common in young adults with peak age of onset 20-40 y/o
no sex difference
the typical clinical picture is a young adults with abdo pain and diarrhoea, often with a palpable mass in the RIF
MALABSORPTION - extensive involvement of the bowel produces malabsorption with steathorrhoea and multiple vitamin deficiencies. it is exacerbated when bowel resections have already occurred
PERIANAL DISEASE - 10% of pts with small bowel Crohn's disease also have perianal disease, ranging from fissures to fistula
SPECIAL IX
crohns disease is associated with anaemia, pos occult blood and occassionally steatorrhoea
serum albumin is low and inflam markers eg CRP and the acute phase proteins are helpful indices of disease activity
additional ix:
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technetium-labelled leucocyte scan shows extent of disease activity - leucocytes are taken up in the inflamed segments and also localise to abscesses
small bowel enema, or enteroclysis - contrast via NG tube and followed fluoroscopically as it passes through the bowel may demonstrate fistulas or strictures in affected segment - usually terminal ileum and ulcerated small bowel may show cobblestone appearance
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TREATMENT
primarily medical, although surgery is appropriate in the management of complications and chronic disease
surg avoided when possible because of the malabsorption that may follow extensive resections of the bowel or the production of blind loops of intestine
MEDICAL MANAGEMENT
initial management is conservative. nutritional support may be required and an elemental diet may be useful
acute episodes are treated with steroids and immunosuppressants such as azathioprine, parenteral nutrition may be required
infliximab, a monoclonal antibody to tumour necrosis factor a (TNF-alpha) - effective for acute exacerbations and fistulating disease
mild symptoms treated with 5-ASA eg sulfasalazine and mesalazine and steroids may be required.
metronidazole may also help
SURGICAL MANAGEMENT
If found at laparotomy in the acute stage, the condition should be left undisturbed since in a high proportion the acute phase may subside completely without further episodes
in the chronic stage of the disease, surgery is indicated for severe or recurrent obstructive symptoms and for the treatment of fistulas into the bladder or skin. recognising that the disease is recurrent and that further resections may be required, surgery should be as conservative as possible. either resection of the affected segment or a strictureplasty is performed.
PROGNOSIS
Recurrence after resection occurs in 50% within 10yrs and repeated ops may be required over the years
CARCINOID SYNDROME
carcinoid tumours are most commonly found in the appendix but may be found anywhere in the alimentary canal and occasionally in the lung
they commonly secrete 5-HT but are rarely symptomatic until they have metastasised to the liver and are thus able to secrete their hormone directly into the systemic circulation, since the liver normally inactivates these hormones
PATHOLOGY
MACROSCOPIC APPEARANCE
yellowish submucosal nodule - the overlying mucous membrane is at first intact but later ulcerates
extension to the serosa leads to fibrosis and obstruction
usually the tumour encircles the bowel at the time of diagnosis and has infiltrated the mesenteric lymph nodes
MICROSCOPIC APPEARANCE
the tumour is made up of Kultschitzky cells which take up silver stains and arise in the crypts of the intestinal mucosa
the tumour is very slow growing and usually presents after the 4th decade - up to 1/4 are multiple
carcinoids of the appendix are relatively benign but 4% eventually
may present early as appendicitis by obstructing the appendix lumen. Those arising in ileum and large bowel spread to regional lymph nodes and the liver
CLINICAL FEATURES
carcinoid tumours present with features related to the primary tumour or metastatic spread or with the carcinoid syndrome because of its endocrine products:
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fludhing (90%) with attackes of cyanosis and a chronic red-faced appearance often precipitated by stress or ingestion of food or alcohol
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abnormalities in heart (pulm and tricuspid stenosis) are late manifestations; lung carcinoids also cause stenosis of the left heart valves (mitral and aortic)
hepatomegaly and a palpable abdo mass produced by the tumout and its secondaries may also be present
SPECIAL IX
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5-Hydroxyindole acetic acid (5-HIAA) urinary concentration (its a product when 5-HT breaks down. 24hr collection contains a raised level
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TREATMENT
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palliation of more extensive deposits by embolizing the hepatic arterial supply via a catheter passed through the femoral artery
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symptoms may be controlled with ocreotide- a somatostatin analogue that inhibits 5-HT release
targeted radiotherapy, using radiolabelled octreotide may have a place in treatment. Even if widespread deposits are present, the tumour is slow growing and the pt mat survive for many years
MECKEL'S DIVERTICULUM
remnant of the vitelointestinal duct of the embryo. lies on the antimesenteric border of the ileum and as an approximation occurs in 2% of pop, arises 2ftfrom caecum and avgs 2inchin length
CLINICAL FEATURES
perforation by a foreign body, presenting as peritonitis
intussusception (ileoileal), often gangrenous by the time the pt comes to operation
acute inflammation, clinically identical to acute appendicitis
peptic ulceration due to heterotopic gastric epithelium in the diverticulum, which bears HCl- secreting parietal cells - particularly occurs in children and characteristically is the cause of malaena at about the age of 10 yrs. rarely the peptic ulcer perforates or gives rise to postcibal pain. the diverticulum may also contain ectopic pancreatic tissue.
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patent vitellointestinal duct, presenting as an umbilical fistula that discharges intestinal contents
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vitellointestinal band stretching from the tip of the diverticulum to the umbilicus, which may snare a loop of intestine to produce obstruction or act as the apex of a small bowel volvulus
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