6.4 Small Bowel, Colon, Rectum, Anus Flashcards
Constipation causes
- Intestinal - colon /ano-rectal; mechanical; colorectal cancer or obstruction
- Extra-intestinal - diet, drugs, neuro-psyc, hormonal, met
Constipation aetiology
- Anorectal dys - pelvic floor muscle fails to relax (puborectal sling m.)
- Slow transient (Colon internia) - slow GI motility. Diagnosed with radio-opaque markers ingested
- Faecal incontinence - inability to delay defaecation to appropriate time
Classification of Faecal incontinence
- Passive - muscular & neurological
- Urge - liquid stool, absent rectal resiviour (tumour)
3 Types in Inflam Bowel Disease
- Ulcerative Colitis
- Crohn’s Disease
- Undetermined colitis
Ulcerative colitis vs. Crohn disease
Ulcerative Colitis
- Multifactorial
- No granulomas
- Starts in rectum (proctitis, left-sided colitis, extensive colitis, pan-colitis)
- Gross bleeding
Crohn disease
- Multifactoral (stronger genetic link)
- Irregular ulcerations
- granulomas
- Small intestines: fistula, abscesses, obstruction
- Large intestines: anorectal dys, haemorrhage
- Gross bleed infrequent
- localized
- NOT IN RECTUM
Acute appendicitis aetiology
Obstructions by:
- Fecalith (hard part of stool)
- Calculus
- Fibrous band
- Parasites
Acute appendicitis presentation
- Bowel pain
- After few hours: severe localized pain in RLQ (after releasing pressure)
- Blooduria: retrocaecally
Acute appendicitis complications
- Perforation (major problem)
- Peritonitis
- Appendiceal abscess
- Pylephlebitis
Intestinal Diverticulum
Def
Classification
Def: saccular out pouching of intestinal lumen
Classification
1. True - all layers
2. False - no muscle layers (only mucosa and sub-mucosa)
Small bowel diverticulum
2 types
Acquired, false
- Colon
- Asym (sym only when infec or inflam)
- Complications: (bac growth, malabsorp, diarrhoea)
Congenital, true
- Merkel’s diverticulum
- Disease of 2’s
- 90% cause problems
- Omphalomesenteric duct
- Pathophysiology: Fibrous band, atttached to diverticulum, with cystic duct or patent (fistula) connection
- Complications: Bleeding, Diverticulitis, Obstruction, Neoplasms
Diverticular disease of colon
Pathogenesis
Complications
- 1 or more acquired false diverticulum
- West diet -> less fibre -> hardened stools
- Sigmoid colon (NOT RECTUM - no taeni coli / longitudinal muscles)
- Diverticulum penetrate circular muscle layer
Complications
1. Asym
2. Painful disease
3. Complicated disease (bleeding, perforation, diverticulitis)
4. Infection break out into peritoneal cavity (contained = abscess, not contained = peritonitis)
5. Incomplete resolve, recurrent diverticulitis (Fistula or Stricture formation)
Intestinal Fistula
Pathogenesis
Clinical features
- Tube that grows from surface to other surface (internal or external)
Clinical features Drainage
- Low output fistula: <200ml/day
- High: >500ml/day
- Intermediate: 200-500 ml/day
Volvulus
Def
2 Types
Def - rotation of segment of bowel on own mesentery axis; close off lumen +blood supply cut off
1. Sigmoid Volvulus
- 65%
- Predisposed: long sigmoid + narrow mesentery base
- Anti-clock wise
2. Caecal volvulus
- 30%
- Caecum abnormally loose from post abdominal wall
- Location (displacement of caecum) not RLQ, but LUQ
- Twist: Clock wise
Intestinal ischaemia
Def
Classification- 2 types
Def - decreased blood flow due to obstruction/thrombosis that obstruct mesenteric structure
Classification
1. Chronic
- Good collateral circulation
-present when all 3 vessels diseased
- pain in midgut after food intake
- pain last several hours
2. Acute
- Aetiology: Embolus, thrombosis, arteritis + hypercoag, Non-occlusive ischaemia, venous & aterial ischeamia
- Hallmark - intense, opiate-resistant pain
What forms in the small bowel in Peutz-Jeghers Syndrome?
Small bowel is major site for non-neoplastic (hamartomatous) polyp formation in PJ syndrome
