Gastrointestinal conditions Flashcards
List six conditions of the GI tract.
constipation irritable bowel syndrome (IBS) haemorrhoids cancer anal fissures and fistula inflammatory bowel disease (IBD)
What is the prevalence of constipation in the UK?
12-12.8 per 1000
worldwide prevalence estimated 14%
2-3 times higher in women than in men
What is the prevalence of IBS?
10-20% of the general population
people aged 20-30 years most often affected
twice as common in women as in men
What is the prevalence of haemorrhoids?
13-36% of the general population
peak prevalence occurs between the ages of 45-65 years in men and women
What is the prevalence of colorectal cancer?
fourth most common cancer in the UK
>41,000 new cases diagnosed each year
risk factors: increasing age, genetics and family history (familial adenomatous polyposis, Lynch syndrome), IBD, dietary and lifestyle factors
What is the prevalence of anal fissures (AF)?
around 1 in 350 people
common in people aged 15-40 years
What is the prevalence of IBD (ulcerative colitis (UC) and Crohn’s disease (CD)) in the UK?
UC - 146,000
CD - 115,000
UC - peak incidence 15-25 years, 2nd peak 55-65 years
What is irritable bowel syndrome (IBS)?
a chronic, relapsing and often life‑long disorder
the exact cause is unknown but it is likely to involve a mix of genetic and environmental factors
symptoms can overlap with other GI disorders (e.g. non‑ulcer dyspepsia, coeliac disease)
people with IBS present to primary care with a wide range of symptoms
List some of the possible biological mechanisms that lead to IBS.
visceral hypersensitivity
abnormal gastrointestinal immune function
changes in colonic microbiota
abnormal autonomic activity
abnormal central pain processing of afferent gut signals (altered ‘brain-gut interactions’)
abnormal gastrointestinal motility
List some of the possible causes or risk factors for IBS.
genetics - twin studies and family studies confirm familial aggregation
enteric infection (e.g. following gastroenteritis)
GI inflammation (e.g. secondary to IBD)
diet (e.g. alcohol, caffeine, spicy and fatty foods) - up to 90% of people report that food triggers symptoms
certain drugs (e.g. antibiotics)
psychosocial factors (e.g. stress, anxiety) - influence the physiological functioning of the GI tract via the brain-gut axis
List five signs of IBS.
bloating (more common in women) change in stool frequency altered stool form rectal mucus altered stool passage (straining, urgency, or incomplete evacuation)
List six symptoms of IBS.
abdominal pain symptoms worse after eating lethargy nausea headache back pain
What factors are required for a diagnosis of IBS?
at least two of the six symptoms for at least 6 months according to:
Abdominal pain and discomfort
Bloating
Change in bowel habit
What further consideration is given to confirm a diagnosis of IBS?
if abdominal pain or discomfort is relieved by defecation or associated with altered bowel frequency or stool form
What is the Rome IV criteria for IBS classification?
four sub-types
classified by the predominant stool type
it is recognised they exist on a spectrum depending on the person’s quantity, intensity, and severity of different symptoms
What are the four sub-types of the Rome IV criteria for IBS classification?
diarrhoea predominant (IBS-D) (most common) constipation predominant (IBS-C). mixed, fluctuating between diarrhoea and constipation (IBS-M) unclassified (IBS-U)
What is the Bristol stool type 1?
separate hard lumps, like nuts (hard to pass)
What is the Bristol stool type 2?
sausage shaped, but lumpy
What is the Bristol stool type 3?
like a sausage, but cracks on the surface
What is the Bristol stool type 4?
like a sausage or snake, smooth and soft
What is the Bristol stool type 5?
soft blobs with clear cut edges
What is the Bristol stool type 6?
fluffy pieces with ragged edges, a mushy stool
What is the Bristol stool type 7?
watery, no solid piece, entirely liquid
How do people with IBS present?
with varying symptom profiles, most commonly ‘diarrhoea predominant’, ‘constipation predominant’ or alternating symptom profiles
IBS diagnosis should be a consideration when an older person presents with unexplained abdominal symptoms
Alongside signs and symptoms reported by the patient, past medical history and physical examination, what blood tests are used to diagnose IBS?
full blood count (FBC)
erythrocyte sedimentation rate (ESR) or plasma viscosity
C‑reactive protein (CRP)
antibody testing for coeliac disease (endomysial antibodies or tissue transglutaminase)
What tests might be requested if there are any concerns or other potential causes?
ultrasound rigid/flexible sigmoidoscopy colonoscopy, barium enema thyroid function test faecal ova and parasite test faecal occult blood hydrogen breath test (for lactose intolerance and bacterial overgrowth)
What are the main non-pharmacological factors involved in the management of IBS?
stress and anxiety diet diarrhoea and/or bloating constipation adequate fluid intake probiotic supplement (taken for at least four weeks) exercise
Why are stress and anxiety related to the management of IBS?
the ability to support patients to identify causes and triggers can reduce the impact of the condition
Why is diet related to the management of IBS?
regular meals
30 mg fibre per day (most people do not eat the recommended amount)
adjusted to the patient’s symptoms
Why is diarrhoea and/or bloating related to the management of IBS?
reduce intake of insoluble fibre (e.g. wholemeal or high-fibre flour and bread, cereals high in bran, whole grains)
avoid foods that exacerbate symptoms (e.g. caffeine, alcohol, carbonated drinks)
Why is constipation related to the management of IBS?
increase soluble fibre supplements (e.g. ispaghula) or foods high in soluble fibre (e.g. oats and linseed)
this is slowly titrated to an optimal level that minimises flatulence and bloating (may take several weeks)
Why is exercise related to the management of IBS?
stimulate the GI system
advised that patients engage in 30 mins of moderate intensity physical activity at least 5 days per week
What is the first-line pharmacological therapy for IBS?
adjusted doses of laxative (lactulose) constipation, or antimotility (loperimide) diarrhoea according to the clinical response
the dose should be titrated according to stool consistency, with the aim of achieving a soft, well‑formed stool (Bristol stool type 4)
What is the second-line pharmacological therapy for IBS?
tricyclic antidepressants (TCAs) if laxatives, loperamide or antispasmodics ineffective e.g. amitriptyline 5-10 mg at night
OSMOTIC LAXATIVES
Lactulose, macrogols, magnesium sulfate - actions
they increase osmotic load
these include magnesium salts, disaccharide (lactulose) and ethylene glycol polymers (macrogols)
OSMOTIC LAXATIVES
Lactulose, macrogols, magnesium sulfate - MOA
poorly absorbed, these agents raise the osmotic load within the gut lumen
this causes ingested water to be retained and water also to be withdrawn from the blood stream
the increased fluid volume promotes movement along the gut
OSMOTIC LAXATIVES
Lactulose, macrogols, magnesium sulfate - abs/distrib/elim
taken orally
not absorbed
OSMOTIC LAXATIVES
Lactulose, macrogols, magnesium sulfate - clinical use
bowel cleansing prior to surgery or examination (MgSO4)
constipation (macrogols and lactulose)
the effects of lactulose develop after 2-3 days
OSMOTIC LAXATIVES
Lactulose, macrogols, magnesium sulfate - adverse effects
abdominal cramps, flatulence
few systemic actions because of low absorption
ANTIDIARRHOEAL AGENTS
Loperamide (similar: diphenoxylate, codeine) - actions
reduces gut motility and secretions
the slower transit time allows for more fluid absorption and more solid stools
ANTIDIARRHOEAL AGENTS
Loperamide (similar: diphenoxylate, codeine) - MOA
agonist action at µ-opioid receptors in myenteric plexus of gut inhibits peristalsis
effects can be reversed by naloxone
loperamide and diphenoxylate, but not codeine, achieve low concentrations in CNS, so have few central effects (including analgesia and addiction)
ANTIDIARRHOEAL AGENTS
Loperamide (similar: diphenoxylate, codeine) - abs/distrib/elim
oral administration
metabolized by hepatic cytochrome P450 system
diphenoxylate is hydrolyzed to an active metabolite
ANTIDIARRHOEAL AGENTS
Loperamide (similar: diphenoxylate, codeine) - clinical use
acute diarrhoea
chronic diarrhoea associated with inflammatory bowel disease
diphenoxylate is commonly administered in a combined preparation with atropine
ANTIDIARRHOEAL AGENTS
Loperamide (similar: diphenoxylate, codeine) - adverse effects
drowsiness and nausea
constipation and abdominal cramps
CNS depression may occur in overdose
