6.4 Small Bowel, Colon, Rectum, Anus Flashcards
(25 cards)
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
To what does metastatic carcinoid lead?
Carcinoid Syndrome (flushing, sweating, bronchospasm, Right-sided cardiac valve lesions) as a result of Serotonin release and related peptides and these not being metabolised by liver
Polyps of large bowel
Pathogenesis
Types
Def - growth/projection from mucous membrane into lumen of hollow organ
- Most common type: Protruded lesions
-Types of polyps: Pedunculate, sessile
- Can produce symptoms of generic or mechanical nature (bleeding, severe mucus, prolapse anus, intusseception)
- Villous adenoma (increased risk in polyp)
Describe Familial adenomatous polyposis
- Autosomal dominant
- Mutant: APC (chromosome 5)
- Will develop in teens (200% chance for cancer if nothing is done)
Most colon cancers are due to polyps. What is the one instance where it is NOT?
Lynch Syndrome
Colorectal carcinoma
Pathogenesis
RF
Pathological
- Most orderly spread cancer (can cure cancer)
- RF: lack of fibre intake, genetic
Pathological
1. Fungating (Polypoid)
2. Annular Stenosis (Early sym: GERD)
3. Malignant ulcer (Tenesmus)
4. Diffusely infiltrating
5. Emergency presentation of colorectal adenocarcinoma
Anal Cancer
-Uncommon
Below dentate line - Adenocarcinoma (same pattern spread and behaviour as rectal carcinoma)
Above - Squamous cell carcinoma (spread to inguinal lymph node)
- Majority = squamous cell carcinoma (HPV, HIV, MSM)
Distribution of Colorectal Carcinoma
- Ascending colon - 30%
- Sigmoid - 25%
- Rectum - 20%
- Descending - 15%
- Transverse - 10%
Haemorrhoids:
Origin
Symptoms
Signs
Grading
Origin - anal canal (internal, external)
Symptoms - bleeding, mucous discharge (+puritis), prolapse, pain (thromboses 4)
Signs - small visible with proctoscopy (3,7,11 o’clock)
Grading
1. No prolapse, prominent blood vessel
2. Prolapse when bear down, spontaneous reduction
3. Prolapse bearing down, manual reduction
4. Prolapsed, inability to reduce, thromboses
When does a fistula-in-ano occur?
Almost always following drainage of peri-anal abscess (spontaneous or surgical)
