Pathology of the small bowel Flashcards
Describe the rough appearance of the small bowel?
Many folds
Microvilli - large surface area
What is the blood supply of the small bowel?
Superior mesenteric artery
What might cause ischaemic of the small bowel?
A blockage in the mesenteric artery
- atherosclerosis of the mesenteric artery
- thromboembolism from the heart
Non occlusive perfusion insufficiency - shock - strangulation obstructing venous return (hernia, adhesion) Drugs (cocain) Hyper viscosity
What might cause a thromboembolism from the heart?
Atrial fibrillation
Is bowel ischaemia usually acute or chronic?
Usually acute
What is the most metabolically active part of the bowel wall?
The mucosa - and thus is the most sensitive to effects of hypoxia
When does most of the tissue damage occur in non occlusive ischaemic?
After the reperfusion
The longer the period of hypoxia to the small bowel the….
Greater the depth of the damage to the bowel wall and the greater the likelihood of complications
As the length of time of ischaemia increases describe the type of infarct you might get?
Mucosal infarct
Mural infarct
Transmural infarct
Describe what might happen after a mucosal infarct?
If blood supply is repaired then regeneration can occur and mucosal integrity is restored
Describe what might happen in a mural infarct?
If blood supply is restored, then repair and regeneration can occur you will be left with a fibrous stricture
Describe what might happen after a transmural infarct?
Gangrene - death if not resected
What are some complications of ichaemia of the small bowel?
Resolution
Fibrous structure, chronic ischaemia, obstruction
Gangrene, perforation, peritonitis, sepsis, death
What is mocker’s diverticulum?
Result of incomplete regression of vitello-intestinal duct
usually in distal ileum
What might Meckel’s Diverticulum cause?
Bleeding, perforation or diverticulitis which mimics appendicitis
usually asymptomatic, incidental finding
Describe roughly tumours of the small bowel?
Primary tumours are rare Secondary tumours (metasteses) more common - ovary -colon - stomach
Name 3 primary tumours of the small bowel?
Lymphomas
Carcinoid tumours
Carcinomas
How would you treat lymphomas of the small bowel?
Surgery and chemotherapy
Describe carcinoid tumours of the small bowel?
They are rare, commonest site is the appendix
Small, yellow, slow growing tumours
Locally invasive
What can carcinoid tumours of the small bowel cause?
Intussusception, obstruction
Flushing and diarrhoea
Describe carcinoma of the small bowel?
Rare, associated with Crohns and coeliac disease
Identical to colorectal carcinoma in appearance
Presents late
Metastases to lymph nodes and liver
Describe appendicitis?
IT is the commonest cause of an acute abdomen
Comments in children
What are the symptoms of appendicitis?
Vomiting, abdo pain, RIF tenderness and increased WCC
What is some of the pathology of appendicitis?
Acute inflammation (neutrophils)
Mucosal ulceration
Serial congestion, exudate
Pus in the lumen
What must acute inflammation involve?
The muscle coat
What is the classical presentation of appendicitis?
Periumbilical pain moving towards RIF
Guarding
Rebound tenderness
What might be some complications of appendicitis?
Peritonitis Rupture Abscess Fistula Sepsis and liver adscess
Wha is coeliac disease?
It is a T cell mediated autoimmune disease of the small bowel in which prolamin (wheat, barley) intolerance causes villous atrophy and malasbroption.
What is coeliac disease caused by?
Caused by an abnormal reaction to a constituent of wheat flour, gluten, which damages enterocytes and reduces absorbtive capacity
What does coeliac diseases have a strong association with?
HLA-B8
Dermatitis herpetigormis
Childhood diabetes
(commoner in Irish)
When can coeliac disease present?
At any stage
What is the normal lifespan of an enterocyte?
About 72hrs
What happens to the enterocytes in coeliac disease?
There is an increasing loss of enterocytes due to IEL mediated damage
leading to a loss of villi and loss of surface area and thus absorption
What might you expect to see down the microscope in coeliac disease?
A flat mucosal biopsy with total villous atrophy
What antibodies might you see in coeliac disease\s?
anti-TTG
anti-endomesial
anti-gliadin
What are some of the symptoms of coeliac disease?
Steatorrhea - due to malabsorption of fats
What might reduced intestinal hormone production lead to in coeliac disease?
Reduced intestinal hormone production leads to reduced pancreatic secretion and bile flow (CCK) leading to gallstones
What are some of the affects of malabsorption due to coeliac disease?
Loss of weight Anaemia Abdo bloating Failure to thrive Vitamin deficiencies
What are some complications of coeliac disease?
T cell lymphomas of the GI tract (rare)
Increased risk of small bowel carcinoma
Gallstones
Ulcerative -jejenoilleitis
