3. Presentation & Pathophysiology of GI Conditions Flashcards
Layers of the GIT (4)
- Mucosal layer
- Submucosal layer
- Muscularis layer
- Serosa layer
Upper GI Tract – Oral cavity to duodenum: Common disorders
- Gastro-oesophageal reflux disease (GORD)
- Peptic ulcer disease (PUD)
- Functional dyspepsia
- These conditions can often have overlapping symptoms
- An individual may also have more than one of these conditions
Peristalsis & LOS relaxation:
- Upper sphincter relaxes when larynx is lifted
- Peristalsis pushes food down
+ Circular fibres behind bolus
+ Longitudinal fibres in front of bolus shorten the distance of travel - Travel time is 4-8 seconds for solids & 1 sec for liquids
- Lower sphincter relaxes as food approaches
GORD: Pathophysiology
- Gastro-oesophageal reflux is the movement of gastric contents into the oesophagus
- Reflux occurs in normal physiological situation:
+ LOS relaxes intermittently during the day to let air out of stomach = transient LOS relaxation - Transient LOS relaxation, however, can be excessive:
+ Becomes pathological when to much gastric juice also refluxes into oesophagus causing symptoms/disease
+ Gastric contents contain acid, erosive to oesophagus
Other contributing mechanisms of GORD (3)
- Hypotensive LOS i.e. not contracting tight enough
- Caffeine, alcohol, chocolate, fats
- Certain medications e.g. beta blockers, nitrates, calcium channel blockers - Hiatus hernia
- Note: Not all people with hiatus hernia have reflux
- Relevant, but not main part of the pathophysiology - Impaired oesophageal peristalsis
- Reduced clearance
Hiatus hernia
- The hiatus is an opening in the diaphragm, where the oesophagus passes through to join the stomach
- The diaphragm acts as additional support, like a sphincter, constricting around the GO junction
- A hernia is when part of an organ protrudes through an opening in the muscle/tissue that is meant to hold it in place
Symptoms of GORD (4)
- Heartburn/chest discomfort
- Burning sensation or discomfort over the chest - Regurgitation
- Food or liquid coming back up into the mouth - Sour or bitter taste in mouth
- May worse after eating or lying down (e.g. bed time)
Complications of GORD (4)
- Reflux oesophagitis
- Peptic stricture
- Barrett’s oesophagus
- Cancer – oesophageal adenocarcinoma
- Reflux oesophagitis
- Damage to oesophageal mucosa by reflux leading to inflammation, ulceration & bleeding
- Odynophagia (painful swallowing)
- Haematemesis (blood in vomit)
- Dysphagia (difficulty swallowing or food sticking)
- Peptic Stricture
- Prolonged inflammation of oesophageal mucosa by reflux can lead to fibrosis and scarring
- Dysphagia (difficulty swallowing or food sticking)
- Barrett’s oesophagitis & its presentation
- Damage to oesophageal epithelium by chronic acid exposure from GORD can lead to Barrett’s oesophagus
- Oesophageal epithelium (squamous epithelium) transforms to become like gastric epithelium (columnar epithelium with goblet cells)
+ Known as intestinal metaplasia - Precursor to oesophageal adenocarcinoma i.e. increased risk
How does Barrett’s present?
May not be associated with specific symptoms
High risk of suspicion in:
- Male, over 50
- Increased BMI
- Smoker
- Chronic GORD, especially poorly controlled
- Oesophageal cancer in GORD
- 2 types: adenocarcinoma (adenoCa), squamous cell carcinoma (SqCC)
- GORD increases risk of oesophageal adenoCa
+ Chronic poorly treated GORD -> Barrett’s -> adenocarcinoma - Smoking, alcohol, certain dietary food increase risk of oesophageal SqCC
- In western countries, oesophageal adenoCa more common
Alarm features in GORD (6)
- Haematemesis (vomiting blood)
- Odynophagia (painful swallowing)
- Dysphagia (difficulty swallowing)
- Vomiting
- Weight loss
- Not improving with PPI treatment
Major functions of the stomach
- Food reservoir
- Digests food
- Antrum mixes & grinds up the food
- Controls passage of food into small intestine
- Pylorus regulates size of particles & controls passage of food (chyme) into small intestine
- Gastric acid secretion
- Other secretions
+ Mucus, HCO3-
+ Intrinsic factor, pepsinogen, prostaglandins
Gastric motility (4)
- Relaxation of fundus (vagovagal reflex)
- Contraction of body & antrum
- Pylorus contracts
- Mixing by retropulsion
- Fundus acts as a food store
- Body & antrum mix food
- Pylorus contracts to limit exit of chyme
Gastric acid secretion
Gastric acid is secreted by:
- Parietal cells located in body of stomach
- Have proton pumps to secrete HCl
- Secrete ~2 L/day of gastric acid
Gastric acid main role is to sterilise food
- Stomach environment hostile to bacteria except for H. pylori
Gastric acid has limited role in digestion
- Some help in absorption of iron & B12
Protection of gastric mucosa from acid (5)
Protective factors:
- Mucous layer
- Bicarbonate secretion
- Epithelial barrier regenerates rapidly
- Prostaglandins
- Mucosal blood flow (sweeps hydrogen ions away)
Dyspepsia
- Dyspepsia describes indigestion – a symptom, not a diagnosis
- Indigestion feels different to different people
- Epigastric discomfort / burning / discomfort
+ May be associated with post-prandial fullness
+ May be associated with early satiety (i.e. full earlier than usual after a meal)
Causes of dyspepsia
Functional dyspepsia accounts for 75%
The remaining 25%:
- Peptic ulcer disease
- GORD
- Coeliac disease
- Biliary & pancreatic diseases
- Diabetes
- Medications
- & several more
Peptic ulcer disease (PUD)
- Helicobacter pylori most common
- Other causes:
+ Aspirin
+ NSAIDs
H. pylori
- Gram-negative bacteria
- Burrows into mucus lining of stomach where it is less acidic
- Up to 85% of people with H. pylori do not have symptoms
- 10-20% lifetime risk of ulcers
- 1-2% lifetime risk of gastric cancer
NSAIDs & Aspirin
- NSAIDs very common treatment for musculoskeletal conditions
- Aspirin commonly used in people with cardiovascular disease
- Frequent cause of hospital admissions although risk per prescription is low
Mechanism of injury with NSAIDs
- NSAIDs & aspirin can cause gastric & duodenal ulceration
- This is mainly via systemic (rather than topical) effects
- Main mechanism is inhibition of COX-1 enzyme involved in synthesis of prostaglandin
Peptic ulcer disease: Presentation
Dyspepsia / epigastric pain
- When hungry, may suggest ulcer is duodenal
- After eating, may suggest ulcer is gastric
Bleeding
- Haematemesis (vomiting blood) or melaena (black stools)
Perforation
- Hole through the GI tract wall
- Severe pain, rigid abdomen
Obstruction (in pylorus or duodenum) from:
- Swelling around ulcer
- Scarring from previous ulcer causing stricture
- Vomiting after eating
Functional dyspepsia
For most people with dyspepsia i.e. indigestion, there are no structural or histological abnormalities to explain for their symptoms
Commonest cause of dyspepsia:
- No structural or tissue abnormality
- Functional GI disorders include irritable bowel syndrome & are characterised by negative investigations
Proposed mechanisms
- Impaired stomach emptying / motility
- Hypersensitivity
- Altered gut microbiome
- Psychosocial dysfunction
How to treat functional dyspepsia (4)
- Proton pump inhibitor
- Prokinetics e.g. domperidone
- Low dose tricylic anti-depressant
- Cognitive behavioural therapy/psychotherapy/hypnotherapy
Alarm features associated with dyspepsia (6)
- Overt GI bleeding (haematemesis/vomiting blood or melaena)
- Vomiting
- Iron deficiency
- Age > 50 years & new onset
- Strong family history of upper GI cancer
- Weight loss
Lower GI Tract – Small intestine & colon: Common disorders
- Infection
- Irritable bowel syndrome (IBS)
- Functional constipation
- Coeliac disease
- Inflammatory bowel disease (IBD):
+ Crohn’s disease & ulcerative colitis
Infective gastroenteritis
Acute diarrhoea is almost always caused by infective gastroenteritis
Symptoms include:
- Diarrhoea, may have bleeding with it
- Vomiting / nausea
- Abdominal pain
- Fever
Typically do not last beyond 2 weeks
- If longer than this, start thinking about causes of chronic diarrhoea
Pathogens (3)
Faecal-oral transmission:
- Bacteria
- Ingestion of toxins produced by bacteria – S. aureus, Bacillus cerus, Clostridium
- Bacteria adheres to mucosa – salmonella, E. coli, Shigella, Campylobacter jejuni, Yersinia, Listeria - Viruses
- Rotavirus, adenovirus, norovirus - Protozoa
- Giardia lamblia, Cryptosporidium, Entamoeba histolytica
Risk factors for infective gastroenteritis (6)
- Food borne (Eating out, BBQs)
- Contaminated water sources
- Travel
- Daycare / nurseries (rotavirus)
- Nursing homes (norovirus)
- Recent antibiotic use (Clostridium difficile)
Management of infective gastroenteritis
Symptoms spontaneously resolve & disease is self-limiting
- Exception: beware in immunocompromised individuals
Avoid anti-diarrhoea agents in those with fever or bloody diarrhoea
- May prolong illness
Hydration
Helminthiasis & intestinal worms (4)
Refers to parasitic worm infection
Majority are intestinal, but not all
Intestinal worms:
- Threadworm (pinworm) – most common worm infection in NZ children
- Tapeworm – sheep farming areas
- Roundworm – rare in NZ, but one of the most common helminthic infection in the world
- Hookworm, whipworm – both rare in NZ
Threadworm/pinworm (Enterobius vermicularis)
- Most common cause of worm infection in NZ
- School-aged children
Pruritis ani – itchy anus
- Worse at night – female adult worm leaves anus to deposit eggs onto the skin around the anus
- Worm can be seen sometimes with the naked eye on anus or bowel motions
Transmission:
- Infected child scratches anus -> eggs lodge beneath nails -> transfer to clothing & furniture -> uninfected child touches surface, put hand in mouth and swallows eggs
Other causes of pruritis ani
Irritation / dermatitis:
- Diarrhoea or straining
- Incontinence
- Scratching
- Over-wiping with toilet paper
- Too much scrubbing with soap & water
- Spicy foods
- Psoriasis
- Other infections e.g. yeast
- Haemorrhoids / anal fissures / skin tags
- Perianal fistula from Crohn’s
- Psychogenic
Bowel habit - Normal?
There is no definition for normal bowel frequency, but what is usual for that individual, whether there has been a change, & whether it is causing problems
Constipation
Too slow:
- Reduced bowel frequency
- Hard / firm stools
- Straining
Chronic constipation
Vast majority of chronic constipation is functional i.e. no organic pathology
In a small number, chronic constipation may be associated with:
- Electrolyte disturbance
- Hormonal – hypothyroidism, diabetes, pregnancy
- Neurological or pelvic muscle disorders
- Obstruction – stricture (diverticular disease related); rectal prolapse
Some medications can also cause constipation e.g. morphine
Alarm features with constipation (5)
- Recent change in bowel habit
- Blood in bowel motions (except when suggestive of haemorrhoids)
- Weight loss
- Iron deficiency
- Strong family history of colorectal cancer
Management of functional constipation (4)
- Fibre
- Fluid intake
- Lifestyle
- Laxatives – osmotic preferable over stimulant
Diarrhoea
Too fast
- Increased bowel frequency
- Loose or watery stools
Remember – acute diarrhoea (< 2 weeks) is almost always infective, but beyond this, start thinking of chronic causes
Chronic diarrhoea causes (4)
Long list of causes including:
- Functional (as part of irritable bowel syndrome)
- Inflammatory bowel disease
- Coeliac disease
- Medications
Alarm features with diarrhoea (5)
- Recent change in bowel habit
- Blood in bowel motions
- Weight loss
- Iron deficiency
- Strong family history of colorectal cancer
Irritable bowel syndrome (IBS)
- Commonest causes of bowel symptoms in young people
- Functional disorder i.e. no structural or tissue abnormality
Symptoms in IBS (2)
- “Swinging” bowel habit – alternates between constipation & diarrhoea
- Abdominal pain typically relieved with defecation
Associated symptoms
- Urgency, feeling of incomplete evacuation
- Passage of mucus
- Abdominal bloating
- Excess flatus
May occur after gastroenteritis (post-infective IBS)
Associated symptoms in IBS (6)
- Fatigue
- Backache, headache
- Urinary symptoms
- Dysmenorrhoea, dyspareunia
- Palpitations
- Poor sleep quality
Other functional GI symptoms:
- Functional dyspepsia
- Early satiety, post-prandial fullness
- Nausea, vomiting
Alarm features in IBS (8)
- Older patient (over 50, but even 40+ should re-consider other diagnoses)
- Short history
- Nocturnal diarrhoea / nocturnal pain
- Bleeding in stools
- Iron deficiency
- Weight loss
- Vomiting
- Family history of colon cancer
Pathophysiology of IBS (3)
- Altered gut motility
- Visceral hypersensitivity
- Central sensitisation
Management of IBS (3)
- Dietary – Low FODMAP diet
- Pharmacologic – tailor to diarrhoea- / constipation- / pain predominant
- Probiotics (may be more useful in post-infective IBS)
FODMAPs
Fermentable Oligo-, Di-, Monosaccharides & Polyols
Oligosaccharide’s – fructose & glucose
Disaccharides – lactose
Monosaccharides – fructose
Polyols – sorbitol, mannitol
Eliminate food containing FODMAPs
Probiotics
- Some evidence of benefit for probiotics in IBS
- May be strain-dependent
Other considerations in IBS (2)
- Lifestyle advice
- Regular meals – unhurried – particularly breakfast
- Reduce stress levels
- Adequate sleep - Psychological therapies
- Many approaches have been shown to be helpful
- Cognitive behavioural therapy / hypnotherapy
Inflammatory Bowel Disease (IBD)
Covers 2 different diseases:
- Ulcerative colitis (UC)
- Crohn’s disease (CD)
Involves genetic & environmental factors
IBD - Genetics
- 1st degree relatives of IBD patients are 3-20x more likely to have IBD than general population
- Like many genes involved & not fully elucidated
- Very uncommon in certain ethnic groups e.g. Maori, Pacific Island
- But despite the role of genes, important to remember that majority of IBD patients (~85%) do not have family history
IBD - Environmental
- Common in “western” industrialised nations
+ Improved living standards – less exposure to enteric infections – less “tolerance” of immune system
Smoking increases risk of Crohn’s disease
Smoking protective for UC
- Often develops within a year of stopping smoking
- Restarting smoking can lead to resolution of inflammation BUT:
- PLEASE DON’T ADVISE PATIENT TO START SMOKING!!!*
IBD - Pathophysiology
- Not fully understood
- Disruption of the integrity of epithelial barrier of the colon
- Certain microbes in the gut may be pathogenic & initiate IBD
Crohn’s disease
- Any part of the GI tract (most commonly colon & small intestine, but can be stomach, oesophagus, mouth etc)
- Discontinuous inflammation i.e. skip lesions, may spare rectum
- Transmural involvement
- Made worse by smoking
Ulcerative colitis
- Colon only
- Continuous inflammation starting at the rectum
- Mucosal involvement only
- Smoking is protective
Symptoms in IBD (3)
- Diarrhoea
- Bleeding in stools
- Abdominal pain
Diagnosis of IBD & differentiation between Crohn’s disease & UC require colonoscopy
Crohn’s disease - other manifestations (3)
Crohn’s can be associated with:
- Stricturing
- Fistulising
- Perianal disease
These do not occur in UC
Crohn’s disease - stricturing (3)
Stricturing disease:
- Abdominal pain & distension
- Vomiting
- Bowels not opening
Crohn’s disease - fistulising (2)
Fistulising disease:
- E.g. Bowel to skin
- E.g. Bowel to bowel
Fistula – an abnormal connection/tract between the gut & another organ/vesse
Crohn’s disease - perianal (3)
- Perianal abscess
- Perianal fistula
- Anal fissure
Extra-intestinal manifestations of IBD
Eyes:
- Episcleritis
- Uveitis
Kidneys:
- Stones (nephrolithiasis)
- Hydronephrosis
- Fistulae
- UTI
Skin:
- Erythema nodosum
- Pyoderma grangrenosum
Mouth:
- Stomatitis
- Apithous ulcers
Liver:
- Steatosis
Billary tract:
- Gallstones
- Sclerosing cholangitis
Joints:
- Spondylitis
- Sclerosing cholangitis
Joints
- Spondylitis
- Sacroilitis
- Peripheral arthritis
Lower GIT - Perianal region: Haemorrhoids & anal fissures
Both most commonly due to constipation
Haemorrhoids:
- External or internal
- Fresh bright bleeding on wiping
Anal fissures:
- Fresh bright bleeding on wiping, often painful defaecation as well
- Very occasionally associated with Crohn’s
Rectal bleeding
Colour of blood:
Black – melaena
- Upper GI tract/small intestine
Bright red – on the paper
- Outlet bleeding i.e. perianal causes
Bright red – mixed with stools
- Left colon
Dark red
- Proximal colon i.e. caecum to transverse colon
- Distal
Lower GI Tract - Colon cancer
- Rectal bleeding, mixed in with stools & dark
- New change in bowel habit, usually diarrhoea
- Older adult
- Iron deficiency
+ Except in young menstruating women or strict lifelong vegetarian - Weight loss
