Lower Gastrointestinal tract Flashcards
Function of large intestine and rectum
Part of the digestive tract.
Most of digestion and absorption already done by this stage.
Mainly absorbs water and electrolytes to form a solid stool.
Acute Appendicitis
sudden onset inflammation of the appendix
Pathology – obstruction of appendiceal lumen by a fecalith, calculus, tumour or worms causing an increased intraluminal pressure and bacterial invasion
Peritonitis: Localised vs Generalised
The peritoneum is the lining of the abdominal cavity and the lining of the organs within the abdominal cavity.
Peritonitis is inflammation of this cavity due to a variety of causes, most commonly infection.
In appendicitis the inflammed appendix on coming in contact with the abdominal wall causes localised peritonitis.
Treatment of Acute Appendicitis
Surgical and/or antibiotics
Anti-biotic Associated Colitis/ Pseudomembraneous Colitis
Acute inflammation of the Colon characterised by the formation of adherent inflammatory pseudomembranes overlying the sites of mucosal injury.
Classically caused by toxins produced by Clostridium difficile that has over grown after competing bowel organism were eliminated by broad spectrum antibiotics
Pseudomembraneous Colitis treatment
Typically develops in patients treated with broad spectrum antibiotics
Fever and lower abdominal tenderness
Treatment-
Speak to microbiology! (stop current antibiotic usually and possibly introduce a new antibiotic)
Hydration
Specifical antibacterial therapy
Inflammatory Bowel Disease
Chronic inflammatory conditions of unknown aetiology affecting the gastrointestinal tract
Two main forms of idiopathic IBD
Crohn’s disease
Ulcerative colitis
Crohn’s disease
Affects from mouth to anus: particularly terminal ileum(30%), colon alone (20%) and ileum and colon (50%)
Skip lesions (not continuous), intervening uninvolved areas often perianal skin involvement (75%)
Transmural inflammation:
Active chronic inflammation
with non-caseating
epithelioid granulomas
Can have Fistula formation
Complications of Crohn’s disease
Anaemia Malabsorption: fat, vitamins A,D,E,K, bile salts Fistulas Extra-intestinal: skin, eyes, joints) Increased risk of bowel carcinoma Bowel obstruction and perforation
Ulcerative colitis
Colon only Starts in rectum spreads proximally Continuous disease (No skip lesions) Mucosal disease (No transmural involvement) May involve whole colon also appendix
Complications of ULcerative colitis
Anaemia: iron deficiency from blood loss
Electrolyte loss from diarrhoea
Extra-intestinal disease: skin, eyes, joints, bile ducts (PSC)
Increased risk of carcinoma: related to duration and severity of disease
Need for surveillance for dysplasia
Neoplasia
Benign Polyps – adenomas
Malignant Adenocarcinoma (cancer)
Different stages and grades of adenocarcinoma affect prognosis and treatment
Colorectal Carcinoma - Aetiology (risk factors)
Genetic factors Familial Adenomatous Polyposis Lynch syndrome (hereditary non-polyposis colorectal cancer) Chronic inflammation IBD: UC, Crohn’s Dietary factors low fibre bile aerobes red meat lack of vitamins, antioxidants
National Bowel Cancer Screening Programme
All population 60-75 years Faecal Occult Blood Test (FOBT) If positive, refer for colonoscopy Look for polyps (adenomas) and carcinomas Refer for definitive treatment
Signs and Symptoms of Bowel Cancer
Depends on the site of the lesion Altered bowel habit Blood PR Iron deficiency anaemia Weight loss Disease can be advanced at the time of the presentation