Conditions of the Large Intestine Flashcards
What is constipation?
A bowel movement less frequent than 3 times per week
OR
Production of a stool which is hard, difficult to pass or painful to pass
What is more important for diagnosis of constipation?
Consistency as opposed to frequency
What does the Rome III (chronic dunctional constipation) criteria state?
Requires 2 or more of the following features that must apply to at least 25% of bowel movements over a 3 month period
- Straining or manual manoeuvres required to facilitate evacuation
- Lumpy/hard stools or if loose stools rare without laxatives
- Sensation of incomplete evacuation or anorectal blockage
- <3 bowel movement each week
What is the aetiology of constipation?
Dietary factors
- Diets low in fibre or water
Lifestyle factors
- Sedentary lifestyles
Medication side effects
- Analgesia, anti-depressants, iron supplements, diuretics
Psychological and neurological factors
- Chronic stress, ignoring the urge to defecate
Organic diseases and metabolic problems
- Diverticular disease, GIT malignancies, IBD, hypothyroidism
What are features that are concerning in regards to constipation?
Onset in middle age or old age
PR bleed, melena or mucous
Weight loss, fever, rectal pain, anorexia, nausea, vomiting
Family history of colorectal cancer
Vomiting
What is targeted management for constipation?
Increase fibre and water intake
Introduce gentle exercise
Drug regimen modification
Address psychological issues e.g. managing stress
Use of biofeedback or neuromuscular retraining
What does the pelvic floor do to support the visera and when would it do this?
Actively contracts during
- Cough/sneeze
- Vomiting
- Lifting heavy objects
- Forced expiration
It does this to support the viscera during periods of increased intra abdominal pressure
What is the role of osteopathy to help someone with constipation?
Visceral techniques
Implications of patient teaching
What is the muscle that holds the rectum and what angle is needed for it to relax?
Puborectalis muscle
- 35 degrees
What are first line therapy options for constipation?
Bulking agents: psyllium
Osmotic laxatives: lactulose, glycerol
How do bulking agents and osmotic laxatives work?
Bulking agents: increase faecal bulk which stimulates peristalsis
Osmotic laxative: exerts osmotic effect which increases intraluminal pressure
What other options are there for constipation?
Stool softeners: ducosate
- Promotes retention of water in faecal matter
Bowel stimulants: senna, bisacodyl
- Direct stimulation of nerve endings in colonic mucosa
*Avoid long-term use
What is irritable bowel disease?
Functional bowel disorder consisting of abdominal discomfort and constipation or diarrhoea (or an alternation between both) in the absence of organic disease or gross structural changes of the intestine
Complex disorder, and its cause is poorly understood
What is functional GIT disorder now referred to?
Disorder of gut-brain interaction
What is the incidence of IBS?
Most common bowel disorder in western countries
Affects up to 25% Australians, greater prevalence in <50
What are the proposed mechanisms of IBS?
Miscommunication between the gut and CNS
Abnormal intestinal motility (dysmotility) and secretion
Visceral hypersensitivity
Alterations on gut microbiota
Genetic susceptibility
In some people there is a correlation between symptoms and:
- Certain foods
- Recent intestinal infections or intestinal overgrowth
- Emotional/psychological factors e.g. stress
Symptoms of IBS frequently occur during or after a stressful event and stressful events in early life may predispose to the development of IBS
What are clinical features of IBS?
Abdominal pain or discomfort
- Common in right or left iliac region or hypograstrium
- Usually relieved by defecation
Variable bowel habit
- Predominant constipation/diarrhoea
- Alternating constipation/diarrhoea
Abdominal distension, excessive flatus and borborygmi (sounds made in tummy)
Nausea, cramping, tenesmus (feeling like you need to defecate even though bowels are empty)
What investigations are made to diagnose IBS?
Stool cultures
FOBT
Colonoscopy
How does loperamide work?
Opioid receptor agonist
- Binds to opioid receptors
- Slows down motility of bowel
- Allows water absorption to blood volume
Does not cross blood brain barrier
- Does not provide euphoria
Bad to take when you have bacteria such as gastro
- You want to excrete the bacteria from body not hold it in
How does hyoscine butylbromide work?
Relax smooth muscle Anti-cholinergic medicine
- Binds to muscarinic receptors
Decrease cramps = relax smooth muscle = anti-cholinergic = down regulating PNS
What is the appendix?
Blind intestinal outpouch arising from the posteromedial aspect of the caecum (inf. to the ileocecal junction)
6-10cm in length
Has a small twisted lumen
Is it intra or retro peritoneal?
Intraperitoneal and has a short mesentery or mesoappendix between the terminal ileum, caecum and appendix
What is McBurney’s point and where does it correspond with?
Corresponds where the appendix attaches to the caecum
What is the histology of the appendix?
Lymphoid tissue
What is the function of the appendix?
Immunity: produces and stores lymphocytes
Reservoir for beneficial gut bacteria
Helps to recolonise the gut when needed
What is appendicitis?
Inflammation of the appendix
What is the incidence of appendicitis?
Most common in surgical emergency of the abdomen
Affects 7-12% of the population
Can develop at any age, peak age for diagnosis 20-30 years old
What is the aetiology of appendicitis?
Pressure builds up in secretory organ (appendix
- Kills wall
- Can no longer get it’s blood supply because there’s so much pressure
What can cause an obstruction of the appendix?
Obstruction of lumen and consequent bacterial infection can be due to stool (faecolith), tumour or foreign body
What is the pathophysiology of appendicitis?
Obstruction of the lumen prevents proper drainage
As mucosal secretions continue, intraluminal pressure increases (decreases mucosal blood flow)
Hypoxia-induced ulceration promotes bacterial invasion and inflammation
Gangrene develops from thrombosis of the luminal blood vessels, followed by perforation of the appendix
What are the complications of appendicitis?
Peritonitis
Abscess formation
What are the clinical features of appendicitis?
Abdominal pain
- Initially vague, constant and felt in the gastric or peri-umbilical region
- Increases over 3-4 hours
Visceral pain is replaced by intense somatic pain in the RLQ
- Somatic pain well localised, sharp and sensitive to stretch e.g. inspiration, rebound tenderness
What is appendicitis mediated by?
Different neural pathway (thoracoabdominal nerves)
Indicates extension of inflammation to parietal peritoneum
What features are common with appendicitis?
Nausea, vomiting, anorexia and fever
- Bowel habit can vary from diarrhoea to sensation of constipation
What is the management of appendicitis?
Appendectomy
- For simple or perforated appendicitis
- Laparascopic or open
Antibiotic therapy
- Alternative to surgery
- Some evidence: resolution of mild-moderate appendicitis with antibiotics alone
- Carries risk or recurrence and the factors leading to the failure of antibiotic therapy are not well known
- Usually reserved for patients too frail to undergo surgery
What are the two major inflammatory bowel diseases?
Ulcerative colitis and crohn’s disease
What is the incidence of inflammatory bowel disease?
> 80,000
Can occur at any age but >15-35 year-olds
Lifelong effects with normal lifespan
Australia has one of the highest prevalences in the world
What is common with both types of inflammatory bowel disease?
Genetic predisposition
Autoimmune dysfunction
Abnormal gut microflora
Environmental factors
What percentage of cases are not easily distinguishable as to which disease is involved?
10-20%
What are the most common features of IBD?
Abdominal pain
Frequent diarrhoea (+/- mucous or blood)
TIredness/fatigue
Fever
Weight loss/anorexia
What makes it harder for the body to absorb nutrients?
Inflammation
What are the less common features of IBD?
Joint pain
Mouth ulcers/sores
Uveitis/episcleritis
Skin rashes
What is ulcerative colitis?
Ulceration of the colonic mucosa, usually in the rectum and sigmoid colon
- 40% of cases spread to the appendix, terminal ileum rarely affected
Where does inflammation begin with ulcerative colitis?
At the crypts of the large intestine, but does not usually spread beyond the submucosa
What does healing with fibrosis due to ulcerative colitis cause?
Pseudopolyp formation (clumps of granulation tissue)
What is crohn’s disease?
Can affect any part of the GIT from mouth to anus
Inflammation begins in the submucosa and spreads to involve the entire thickness of the intestinal wall
What are the most common sites for crohn’s disease?
Terminal ileum, ascending colon and transverse colon
What are skip lesions?
Inflammation can affect some regions of the GIT but not others (rectum is seldom involved)
What is the main goal of crohn’s disease treatment?
To reduce inflammation and symptoms and heal the bowel
What medications are used for IBD?
Anti-inflammatories
- Corticosteroids
- 5-Aminosalicylic Acid (5-ASA)
Biological agents
- Anti-TNF antibodies
Immunosuppressants
Anti-diarrhoeal agents
What are the mechanisms of action of anti-inflammatories for IBD?
Corticosteroids (prednisolone, budesonide, hydrocortisone)
- Oral: enteric coated, sustained-release tablets
- Suppository/enema
5-Aminosalicylic Acid (sulphasalazine)
- Prostaglandin synthesis inhibitor
What is the mechanism of action of anti-TNFa antibodies?
Targets and reduces levels of cytokine TNFa
How do corticosteroids decrease bone density?
Downregulation on osteoblastic activity
Upregulation of osteoclastic activity
- Breakdown of bone
At risk of bone weakening
- Osteopenia or osteoporosis
* Risks for HVLA
* Absolute contraindication
What is the aetiology of colorectal cancer?
Complex interplay between environmental and genetic factors
- Dietary
- Smoking
- Alcohol
- Inflammatory bowel disease
- Familial component
*Familial adenomatous polypsis
How can dietary factors and smoking cause colorectal cancer?
Dietary:
- Low-fibre diets, high-fat diets, diets high in charred red meats
Smoking:
- Smoking 40 cigarettes a day increases the risk of bowel cancer by around 40% and nearly doubles the risk of bowel cancer death
How can alcohol and IBD cause colorectal cancer?
Alcohol:
- Bowel cancer risk increases significantly when two or more alcoholic drinks are consumed per day
IBD:
- Risk is related to the length of time that inflammation has been present, and the site and severity of the disease
What are polyps?
Benigns, finger-like projections of mucosal epithelium
What is the pathophysiology of colorectal cancer?
most tumours develop in pre-existing adenomatous polyps
Risk of malignancy increases with polyp size
50% chance of finding neoplastic cells in polyps >4cm
What are the most common sites for polyps?
Rectum (M) and sigmoid (F)
What are the second most common sites for colorectal cancer?
Caecum and ascending colon
What are the clinical features of colorectal cancer?
Malignant polyps can ulcerate: bloody or mucoid diarrhoea
- Distal bowel - frank blood
- Proximal bowel - occult blood
- Caecal tumours - asymptomatic until large
Alternatively, a large polyp can restrict bowel lumen: constipation
Lower abdominal pain: can vary from vague discomfort to colic
Palpable mass
Non-specific features
Features of metastasis (direct spread, lymphatics, blood)
- Liver mets are especially common
What is the management of colorectal cancer?
Diagnosis - colonoscopy with biopsy
Surgical resection (only definitive treatment)
- Polyp - endoscopic mucosal resection
- Simple resection w end to end anastomosis
- temporary/permanent colostomy
Radiotherapy and chemo
What is involved in screening for colorectal cancer?
Faecal occult blood test and endoscopy
- FAP: regular endoscopy starting at age 10
General population: Australian medical guidelines recommend screening using an immunochemical faecal occult blood test every 2 years between ages 50-74
