Functional and Infective Pathology of the Lower GI Tract Flashcards
Diarrhoea definition
the passage of three or more loose or liquid stools per day (or more frequent passage than is normal for the individual)
acute diarrhoea last for
0-14 days
Persistent diarrhoea lasts for
14 days-4 weeks
Chronic diarrhoea lasts for
4+ weeks
Why worry about diarrhoea?
- significant amount of morbidity (but little mortality)
- dehydration:
- increases risk of life threatening disease in
young/old - electrolyte imbalance (NA,K,HCO3)
- can lead to acidosis
- increases risk of life threatening disease in
- chronic diarrhoea can negatively affect: wellbeing,
mental health, activity, limited diet, social isolation
Diarrhoea
how infections cause diarrhoea
4 categories of causes of acute diarrhoea:
- infection
- medication
- acute presentation of chronic pathology
- other
Causes of acute diarrhoea: infection:
- viral (norovirus, rotavirus)
- bacterial (salmonella, clostridum difficile, cholera)
- parasites (giardia lamblia)
Causes of acute diarrhoea: ,edications:
- laxatives
- antibiotics (macrolides)
- allopurinol
Causes of acute diarrhoea: other:
- anxiety
- food allergy
- GI inflammation (acute appy, intestinal ischaemia)
Most cases of infectious diarrhoea are ——- and ——-/ 50% of cases last
- viral and self-limiting
- <1 day
typically viral untreated infectious diarrhoeas last
2-3 days
typically bacterial untreated infectious diarrhoea last
3-7 days
typically protozeal untreated infectious diarrhoea lasts
weeks-months
Assessing acute diarrhoea: history:
- onset, duration, severity
- character (watery, fatty, blood stained, mucous)
- triggers (infective contacts, diet, travel)
- associated features: vomiting, fever, abdo pain, med
changes, stress, surgery - Red flags: blood, recent antibiotics, weight loss,
dehydrationn, nocturnal symptoms
Assessing acute diarrhoea: examination:
- assess fluid status: tachycardia, reduced skin turgor,
dryness of mucous membrane, delayed capillary refill,
decreased urine output, hypotension, confusions - abdominal exam: pain, tenderness, distension, mass,
increased or decreased bowel sounds - DRE: tenderness, stool consistency, mass,
blood/mucous
Investigating acute diarrhoea
- not always needed if the patient is well and the length
of symptoms are short/quickly resolving - stool testing: exclude infections, pt vulnerable
- blood tests: FBC, ESR. CRP,LFTs, U&Es, iron) to rule out
other causes
Managing acute diarrhoea:
- usually nothing: hydration, hypertonic saline/glucose
sol - if unwell, hospital:
- subsequent diagnostics once acute episode settles
- even with proven infection, antibiotics rarely used
- dehydration most common concern
5 categories of chronic diarrhoea causes:
- diet
- bowel disease
- constipation and impaction
- drugs
- others
Chronic Diarrhoea Causes: Diet:
- malabsorption
- artifical sweeteners
- excessive sorbitol
- caffeine
- alcohol
Chronic Diarrhoea Causes: Bowel Disease:
- IBS
- IBD
- microscopic colitis
- coeliac disease
- etc
Chronic Diarrhoea Causes: Constipation and Impaction:
…
Chronic Diarrhoea Causes: Drugs:
- macrolides
- ACE inhibitor
- NSAIDs
- metformin
Chronic Diarrhoea Causes: other:
- infection
- endocrine
- CF
- lymphoma
- hormone secreting tumours
Assessing chronic diarrhoea: history:
- onset, duration, frequency, severity of symptoms
- character (watery, fatty, blood stained, mucous)
- triggers (infective, diet, const, drugs, IBS, IBD)
- associated features: vomiting, fever, abdominal pain,
changes in medication, stress, past surgery - red flags: blood in stool, Abx, weight loss,
dehydration, nocturnal symptoms
Assessing chronic diarrhoea: examination:
- assess fluid status: tachycardia, reduced skin turgor,
dryness of mucous membranes, delayed capillary
refill time - abdo exam: pain, tenderness, distension, mass,
increased or decreased bowel sounds,, organomegaly - DRE: rectal tenderness, stool consistency, masses,
blood/mucous
Investigating chronic diarrhoea:
- stool MC&S: add in parasitology, infection
- blood tests: FBC, B12/folate, CA, ferretin, hormones)
- qFIT: faecal calprotectin, feacal elastase
- imaging: USS, CT/MRI, endoscopy
qFIT stands for
Quantitative faecal immunohistochemical test
qFIT:
- 1st line investigation for changes in bowel habits (rule
out bowel cancer) - contra-indicated for rectal bleeding
- if normal (<10 micrograms Hb/g faeces) risk of
bowel cancer is 0.4% - if >10 risk of bowel cancer 6%
- if >150 risk of bowel cancer 31%
- if normal (<10 micrograms Hb/g faeces) risk of
- reduces need for invasive investigations
Managing chronic diarrhoea:
- treat the underlying cause
- supportive care for patient
Irritable Bowel Syndrome (IBS) definition
abdo pain which is either releated to defecation and/or associated with altered stool frequency or appearance
AND there are at least two of the following:
- altered stool passage (straining, urgency,
incomplete evacuation)
- bloating or distension
- worsened by eating
- passing rectal mucous
AND:
- alternative conditions are excluded
IBS management:
- rule out alternative causes and REASSURE
- dietary manipulation:
- diarrhoea:
- reduce insoluble fibre intake
- reduce food triggers (caffeine, alcohol,
carbonated drinks)
- constipation:
- soluble fibre supplements or food high in
soluble fibre
- maintain adequate fluid intake
- low FODMAP diet, fermentable oligosaccharide,
disaccharides, monosaccharides, polyols)
- diarrhoea:
- probiotics may help
IBS medical therapies:
Diarrhoea:
- Loperamide (antimotility)
- most common side effect is constipation, cardiac
arrhythmias in higher doses
- antispasmodic drugs for abdo cramps
Constipation:
- Laxatives
- bulk forming
- avoid lactulose
Low dose tricyclic antidepressant amytriptyline 4 weeks, >90% will respond to varying levels of success
Constipation definition:
- bowel movements less than 3 times a week
- excessive straining
- associated abdominal pain or bloating
- change in intrinsic pattern
Constipation can be categorised by either
Time:
- acute: 0-3 months
- chronic 3+ months
Causes:
- Primary (functional)
- Secondary (organic)
Why worry about constipation?
- distressing
- concerns over underlying cause
- increased morbidity (especially in elderly/frail)
Consequences of constipation:
- nausea/appetite loss
- confusion
- functional decline
- overflow diarrhoea
- urinary retention
- haemorrhoids
- anal fissures
Assessment on Constipation: History:
- how long?
- speed of onset?
- getting worse/better?
- triggers: lifestyle, stress, meds, surgical changes)
- associated symptoms (bleeding, loss of weight, abdo
pain) - PMHx of GI disease
Assessment of constipation: examination:
- well/unwell
- general exam: pyrexia, jaundice, cachexia
- abdominal examination: tenderness, distention,
masses - rectal exam: masses, empty rectum v impacted stool
Investigations for Constipation:
- blood tests: FBC, inflamm markers, iron, liver function,
thyroid, HbA1c, Ca, B12 and folate) - stool tests: qFIT, calprotein
- imaging: abdo X ray, CT scan
- endoscopy
- special investigations: bowel transit study, pelvic floor
investigations
3 categories of acute constipation causes:
- functional: dehydration, diet, stress
- medication: opiates, loperamide, iron
- acute presentation of chronic pathology: bowel
obstruction
Opiates and Constipation:
- 5 classes: kappa, delta, mu, zeta, nociception
- all G coupled protein receptors
- opiod receptors inhibit calcium channels leading to
decreased neurotransmitter release - activation of mu and delta receptors, leading to
reduced GI motility and increased sphincter tone
leading to constipation - GI Tract can develop a tolerance ot opiods
- loperamide acts by binding specifically to mu
receptors promoting constipation
Acute constipation Management:
- remove the insult
- support the patient
- may need laxatives
Chronic Constipation 6 categories of causes:
- functional constipation
- medication
- colonic
- pelvic floor/defecator disorders
- endocrine
- neurological
Chronic Constipation Causes: Functional Constipation:
- dehydration, diet, stress, IBS, pregnancy, withholding
Chronic Constipation Causes: Medication:
- opiates, loperamide, iron, calcium channel blockers
Chronic Constipation Causes: colonic:
- cancer
- IBD
- diverticular disease
Chronic Constipation Causes: Pelvic Floor/Defecator disorders:
- rectal prolapse
- recocele
- pelvic floor dyssynergia
Chronic Constipation Causes: Endocrin:
- hypothyroidism
- hypercalcaemia
- diabetes mellitus
- porphyria
Chronic Constipation Causes: ENurological:
- MS
- spinal cord lesions
- Parkinson’s
Management of Chronic Constipation:
- remove the insult where possible
- make the environement as facourable for bowel
opening as possible:
- adequate fibre and fluid intake, removing
constipating meds - resolve faecal impaction first if present:
enemas/suppositories - laxatives
- neuromodulation (sacral nerve stimulation)
- surgery: total colectomy, stoma
Important causes of constipation:
- diverticulitis
- bowel obstruction
- bowel cancer
Diverticular disease
- protrusion of mucosal pouches through bowel wall
musculature - intimately linked with constipation:
- cause or effect
- poor dietary fibre implicated - > 90% have no symptoms
Proximal bowel obstruction
bowels may still be functional despite obstruction; history can be misleading
Absolute constipation
no passage of stool or passing of flatus: often indicates distal mechanical obstruction of colon
Important to establish the cause of bowel obstruction quickly:
- determination if spontaneous resolution possible
- adhesional small bowel obstruction; will settle with
surgery in >90% cases
Causes of Bowel Obstruction: Extrinsic:
- abdominal masses
- adhesions.sar tissue
- hernias
Causes of Bowel Obstruction: Bowel wall problem:
- neoplasia
- inflammatory stricture
Causes of Bowel Obstruction: Luminal:
- bezoar/foreign body
Management of Suspected Bowel Obstruction:
- immediate resuscitation if unwell
- early investigation essential: CT highly sensitive and
specific for bowel obstruction - decision to make: will this settle or is intervention
needed - closed loop lasege bowel obstruction is an
emergency:
- competent ileocaecal valve (50%) prevents reflux
into ileum
- beware the obstructed colon with right lower
abdominal pain
Bowel Cancer:
- can have very vague or no GI symptoms
- iron deficiency anaemia and qFIT increases concerns
of bowel ca
Laxatives
Other laxatives:
Side effects: Laxatives:
