Pathology of Small bowel Flashcards
What supplies the small bowel?
Superior mesenteric artery
What are the 2 types of ischeamia of the small bowel?
Mesenteric arterial occlusion
Non-occlusive perfusion insufficiency
What causes mesenteric arterial occlusion?
Mesenteric artery atherosclerosis
Thomboembolism from the heart (A.fib, subactute endocarditis, mural thrombus)
What can cause non occlusve perfusino insufficiency?
Shock
Strangulation obstructing venous return (hernia, adhesion)
Drugs e.g. cocaine (vasospasm)
Hyperviscosity
What part of the bowel is most sensitive to the effects of hypoxia?
The mucosa is the most metabolically active part of the bowel wall and therefore the most sensitive to the effects of hypoxia
What occurs the longer the hypooxia occurs?
The greater the depth of the damage to the bowel wall and the greater the likelyhood of complications
When does the tissue damage occur in non occlusive ischaemia?
After reperfusion
What are the complications of ischaemia of the small bowel?
Resolution
Fibrosis, stricture, chronic ischaemia, mesenteric angina, obstruction
Gangrene, perforation , peritonitis, sepsis and death
What is meckel’s diverticulum?
A result of incomplete regression of the vitello-intestinal duct. Tubular structure, 2 inches long, 2 foot above the ileocaecal valve
May contain heterotropic gastric mucosa
What are the complications of meckel’s diverticulum?
Bleeding, perforation or diverticulitis that mimicks appendicitis
What are the primary tumours that can occur in the small bowel (rare)?
Lymphomas
Carcionid tumour
Carcinomas
What is non-hodgkin’s lymphoma?
Non-Hodgkin lymphomas (NHLs) are tumors originating from lymphoid tissues, mainly of lymph nodes.
What is a carcinoid tumour?
Carcinoid tumors are of neuroendocrine origin and derived from primitive stem cells in the gut wall
What is carcinoid sydrome?
Paraneoplastic syndrome that causes flushing and diarrhea, and less frequently, heart failure, emesis and bronchoconstriction. It is caused by endogenous secretion of mainly serotonin and kallikrein.
What is a carcinoma?
Cancer of the epithelium - can be basal, squamous cell, adenocarcinoma
Where are carcinoid tumours of the small bowel usually found?
Commonest site is the appendix, small, yellow, slow growing tumours
What are carcinoma’s of the small bowel associated with?
Crohn’s disease and coeliac disease. Crohn’s predisposes to adenocarcinomas
Where will carcinoma’s of the small bowel metastasise to?
Lymph nodes and liver
What are the symptoms of appendicitis?
Vomiting, abdominal painn, right iliac fossa tenderness and increased white cell count
What is the aetiology of acute appendicitis?
Unkown Faecoliths Lymphoid hyperplasia Parasites Tumours (rare)
What is the pathology of acute appendicitis?
Acute inflammation (neutrophils) Mucosal ulceration Serosal conngestion , exudate Pus in lumen Acute inflammation MUST involve the muslce coat
What are the complications of acute appendicitis?
Peritonitis Rupture Abscess Fistula Sepsis and liver abscess
What is coeliac disease?
Abnormal reaction to a connstituent of wheat flour, gluten, which damages enterocytes annd reduces absorbtive capacity
What are the metabolic effects of coeliac disease?
Malabsorbtion of sugars, fats, amino acids, water and electrolytes
Reduced inntestinnal hormone production leads to reduced pancreatic secretion and bile flow (CCK) leading to gallstones
What does malabsorbtion of fats lead to?
Steatorrhea
What is stearorrhea?
The excretion of abnormal quantities of fat with the faeces owing to reduced absorption of fat by the intestine.
What are the effects of malabsorbtion?
Loss of weight Anaemia (Fe, Vit B12, Folate) Abdominal bloating Failure to thrive Vitamin deficiencies
What are other complications (excluding malabsorbtion) of coeliac disease?
T-cell lymphoma
Increased risk of small bowel carcinoma
Gall stones
Ulcerative-jejenoilleitis
