Pathology of small bowel Flashcards
(37 cards)
what are 2 types of ischaemia of the small bowel?
1) mesenteric arterial occlusion
2) non-occlusive perfusion insufficiency
what 2 things can lead to mesenteric arterial occlusion?
- mesenteric artery atherosclerosis
- thrombi-embolism from heart (e.g. A. Fib)
what 4 things could lead to non-occlusive perfusion insufficiency?
- shock
- strangulation obstructing venous return (e.g. hernia, adhesion)
- drugs e.g. cocaine
- hyper-viscocity
what is bowel ischaemia usually?
= acute but can be chronic
what is the most metabolically active part of the bowel wall?
= mucosa is the most metabolically active part
what is the consequence of the mucosa being the most metabolically active part of the bowel wall?
= the most sensitive to effects of hypoxia
- longer period of hypoxia, greater the depth of damage to the bowel wall and the greater the likelihood of complications
when does most of the tissue damage occur in non-occlusive ischaemia?
= after re-perfusion
what is acute ischaemia classified by?
the degree of infarction (obstruction of the blood supply) caused
describe the 3 areas that are infracted as length of time of ischaemic increases?
1) mucosal infarct (regeneration)
2) mural infarct (stricture)
3) transmural infarct (gangrene - death)
what are the complications of ischaemia of small bowel?
- resolution
- fibrosis, stricture, chronic ischaemia, ‘mesenteric angina’ and obstruction
- gangrene, perforation, peritonitis, sepsis and death
what is Meckel’s diverticulum?
an outpouching or bulge in the lower part of the small intestine.
what is Meckel’s diverticulum a result of?
= involute regression of vitello-intestinal duct
describe the structure of Meckel’s diverticulum?
= tubular structure
- 2 inches long
- 2 foot above IC valve in 2% of people
what may Meckel’s diverticulum contain and what might it cause?
Contain
= heterotopic gastric mucosa
Cause
= bleeding, perforation or diverticulitis which mimics appendicitis
describe the symptoms of Meckel’s diverticulum?
= asymptomatic, incidental finding
what type of tumours are rare and more common of the small bowel?
- primary tumours = rare
- secondary tumours (metastases) = common
give examples of 3 types of secondary tumours (metastases) of small bowel?
- ovary
- colon
- stomach
give 3 examples of primary tumours of small bowel?
- lymphomas
- carcinoid tumours
- carcinomas
describe lymphomas of small bowel.
= they are rare
- all Non-hodgkins in type
- maltomas (B cell) derived
- enteropathy associated T-cell lymphomas (associated with coeliac disease)
Treatment;
- surgery
- chemo
describe carcinoid tumours of small bowel.
= rare
- commonest site = appendix
- small, yellow, slow growing tumours
- locally invasive
- can cause inttussuscepttion, obstruction
- produce hormone like substances
- if they metastases to liver occur a carcinoid syndrome occurs
- flushing & diarrhoea
describe carcinomas of small bowel.
= rare
- associated with Crohn’s disease and coeliac disease
- identical to colorectal carcinoma in appearance
- presents late
- metastases two lymph nodes and liver
what is appendicitis a common cause of and who is it more common in and describe its symptoms?
= an acute abdomen
More common = in children, but occurs in adults
Symptoms;
- vomiting
- abdominal pain
- RIF (right iliac fossa)
- tenderness
- increased WCC (white cell count)
what are 5 causes of acute appendicitis?
- unknown
- faecoliths (dehydration)
- lymphoid hyperplasia
- parasites
- tumours (rare)
describe 4 pathological features of acute appendicitis
- acute inflammation (neutrophils invade appendix wall)
- mucosal ulceration
- serosal congestion, exudate
- pus in lumen
