Week 4 - Colon and Associated Disorders Flashcards
Other than pain, what other clinical features may be associated with appendicitis?
- nausea
- vomiting
- anorexia
- fever
- bowel habit can vary from diarrhoea to a sensation of constipation
Describe strategies that might help to minimise the risk for (or promote the early detection of) colorectal cancer.
- screening (faecal occult blood test and endoscopy if 1st degree relative has had CRC from age 25)
Outline the management of irritable bowel syndrome (include potential pharmacological interventions within your discussion)
- reassurance that there is no serious underlying pathology
- appropriate strategies to manage the constipation and diarrhoea
- food elimination approaches may be helpful in some cases
- pharmacological agents (e.g. serotonin-receptor modulators incl. antagonists and agonists, anti-spasmodics)
Differentiate a haustral contraction from a mass movement
Haustral contractions occur every 30 minutes
- they are short-lived contractions (mainly in ascending and transverse colon)
- initiated by ENS when individual haustra fill with food residue
Mass movements occur 3-4 times daily
- they are powerful, prolonged contractile waves that force contents towards rectum
Describe four functions of the large intestine
Digestion - enteric bacteria ferments indigestible carbohydrates and mucin
Absorption - water, electrolytes (NaCl) and vitamins
Propulsion - contractions to transport faecal matter, towards rectum
Defecation - removal of faecal matter from the body
List common aetiologies for both types of diarrhoea.
Acute diarrhoea
- infectious gastroenteritis/enteritis
- dietary issues
- adverse drug reactions
Chronic diarrhoea
- chronic infective diarrhoea
- intestinal disorders
- adverse drug reactions
Differentiate acute diarrhoea from chronic diarrhoea.
Acute diarrhoea
- sudden of >3 loose stools/day
- lasts less than 14 days
Chronic diarrhoea
- present for at least 4 weeks
Differentiate the terms internal haemorrhoid and external haemorrhoid
Internal haemorrhoids - varicosity of the superior rectal vein (proximal to pectinate line)
External haemorrhoids - varicosity affecting the perianal venous plexus (distal to pectinate line)
How might the defecation reflex be affected in a patient with cauda equina syndrome?
Cauda equina syndrome may involve significant lumbar disc herniation, resulting in compression of a lumbar spinal cord. This may affect signals reaching the sacral nerves below, resulting in an inability to complete the defecation reflex.
Summarise the clinical features of irritable bowel syndrome
- abdominal pain or discomfort (R or L iliac region, or hypogastrium)
- variable bowel habit
- abdominal distension, excessive flatus and borborygmi
- nausea, cramping, tenesmus (recurrent inclination to evacuate the bowels)
What clinical features might make you suspicious of colorectal cancer?
- constitutional SSx (anorexia, malaise, fever)
- malignant polyps can ulcerate: bloody or mucoid diarrhoea (distal bowel = frank blood; proximal bowel = occult blood; caecal tumours = asymptomatic until large)
- lower abdominal pain
- palpable mass
Compare and contrast the following elements of ulcerative colitis and Crohn’s disease:
b) Aetiology
UC - undetermined; genetic, immunological and infectious factors are usually involved
CD - strong evidence for autoimmune involvement
List two classes of medication that can be used in the management of inflammatory bowel disease. For each class of medication, provide an example and describe the mechanism of action.
- anti-inflammatory agents (e.g. corticosteroids, 5-aminosalicyclic acid)
5-ASA mechanism = prostaglandin synthesis inhibitor - biological agents (anti-TNFa antibodies)
mechanism = targets and reduces levels of cytokine TNFa - immunosuppresants
- anti-diarrhoeal agents
How does the mucosa change at the recto-anal junction? What does this change in cell type reflect?
Rectal mucosa is composed of simple columnar epithelium (with a high concentration of goblet cells), whilst anal mucosa is composed of stratified squamous epithelium.
This transition reflects the greater abrasion that this region receives.
Define the term constipation
Several definitions exist:
- a bowel movement less frequent than three times a week
- production of a stool which is hard, difficult to pass or painful
- consistency is more significant than frequency for diagnosis
Rome III Criteria for Chronic Functional Constipation:
Requires 2 or more of the following features:
- straining or manual manoeuvres over a 3-month period
- lumpy/hard stools or if loose stools rare without laxatives
- sensation of incomplete evacuation or anorectal blockage
- <3 bowel movements each week
Describe the typical pattern of abdominal pain associated with appendicitis. The nature of appendicitis pain usually changes as the disease progresses – why is this the case?
- begins as a vague gastric or peri-umbilical region (T10)
- increases over 3-4 hours
- visceral pain is replaced by intense somatic pain in the RLQ
- this change is mediated by a different neural pathway (thoracoabdominal nerves)
- this indicates extension of inflammation to parietal peritoneum (somatic nerve supply)
- the somatic pain is sharp, well-localised and sensitive to stretch
What strategies can be used to manage functional constipation?
- increase fibre and water intake
- introduce gentle exercise
- drug regime modification
- address psychological issues (e.g. managing stress)
- use of biofeedback or neuromuscular retraining
Define the term irritable bowel syndrome. How is the disorder diagnosed?
It is a functional bowel disorder consisting of abdominal discomfort and constipation or diarrhoea (or an alternation between both). There is no structural abnormality.
IBS is a diagnosis of exclusion (must exclude other pathologies first)
- stool cultures
- faecal occult blood test
- colonoscopy
Compare and contrast the following elements of ulcerative colitis and Crohn’s disease:
f) Potential complications
UC - toxic megacolon
- if ulceration is severe enough to affect muscularis
- results in dilated, atonic section of bowel
CD - chronic fissures, fistula development
- coloenteric, colovesical, colovaginal
Summarise the risk factors for colorectal cancer
- dietary factors (low-fibre diets, high-fat diets, diets high in charred red meats)
- smoking
- inflammatory bowel disease
- familiar component (first-degree relative) (familiar adenomatous polyposis
Outline the different classes of laxatives. For each class, briefly explain the mechanism of action and provide an example of a medication from that class.
- Bulking Agents (psyllium)
= increase faecal bulk which stimulates peristalsis - Osmotic Laxatives (lactulose) = exerts osmotic effect (draws water to bowel) which increases intraluminal pressure
- Stool Softeners (docusate) = promote the retention of water in faecal matter
- Bowel Stimulants (senna) = direct stimulation of nerve endings in colonic mucosa
- Opioid Antagonists (naloxone) = competitive antagonist at GIT opioid receptors
Outline the management of haemorrhoids
- rectal examination
- sigmoidoscopy/colonoscopy to exclude other causes of bleeding
- symptom relief (oral or topical preparations to reduce pain and/or inflammation, hydrocortisone combining corticosteroid with local anaesthetic)
- surgery is required for third and fourth haemorrhoids
It is important to recognise situations in which constipation might be due to a sinister cause. Describe features associated with constipation that would warrant special concern and referral.
- onset in middle age or old age
- per rectal bleeding, melena (dark, offensive-smelling stool), or mucus
- weight loss, fever, rectal pain, anorexia, nausea, vomiting
- family history of colorectal cancer
Compare and contrast the following elements of ulcerative colitis and Crohn’s disease:
e) Clinical features
UC - initial attack is most severe; large volumes of water diarrhoea +/- blood, mucus, pus; may be constipation due to strictures from scar tissue or reflex bowel spasm; lower abdominal pain, tenderness or cramping; proctitis leads to tenesmus severe epsiodes: - >20 motions/day - dehydration, tachycardia - fever - anaemia
CD - depends on site affected, extent and duration of disease; early stages may mimic irritable bowel or even a peptic ulcer; diarrhoea, weight loss, abdominal pain
If colon affect = blood, pus, mucus
If small bowel affected = issues related to malabsorption
