tbl 4 clinical: constipation and diarrhoea Flashcards
Constipation – symptom rather than a disease
- Infrequent stools (<3x per week) and/or difficulty to pass bowel movements
o Straining or subjective sensation of hard stools, difficulty expelling stools, sensation of incomplete evacuation (__________), hard or lumpy stool, need for manual manoeuvres to pass stool
- In the ___________, type 1 and type 2 are diagnostic of constipation
- Common causes of constipation – can normally
be elucidated from clinical history
o Low dietary fibre, change in routine, lack of exercise, insufficient fluid intake, irritable bowel syndrome (IBS)
Tenesmus;
Bristol stool scale
Secondary causes of constipation
Structural
- Colonic (e.g. colon cancer, stricture)
- Anorectal (e.g. large ________)
Endocrine
- Diabetes mellitus
- Hypothyroidism
Metabolic
- _______
- Hyper or hypocalcaemia
- Uraemia
Infiltrative
- Scleroderma
- Amyloidosis
Neurological
- Parkinson’s disease
- Spinal cord disease
- Autonomic neuropathy
- Multiple sclerosis
Psychological
- _____________
rectocele;
Hypokalaemia;
Anorexia Nervosa
Drug-related causes of constipation
- Analgesics: __________, NSAIDs
- Antihypertensives :Calcium channel blockers, __________, α2-agonists
- Antacids: Containing ________, calcium
- Anticholinergics, antidepressants, antihistamines, antiparkinsonian agents
- Others: Iron, cholestyramine, calcium supplement
Opiates;
diuretics;
aluminum
Constipation in children
- As with adults, children can have common causes of constipation as well as rarer causes
- Some common causes of childhood constipation are similar to those in adults (e.g. diet)
- Children may also exhibit toilet phobia or be stressed about toilet training, leading to constipation
- Childhood constipation may also indicate congenital abnormalities (much rarer)
o _____________ – malformation of gut nervous system
o Anorectal malformation
o Spinal cord abnormalities, i.e. spina bifida and cerebral palsy
o Cystic fibrosis
Hirschsprung’s disease
Complications of constipation
- Constipation rarely causes any long-term complications
- However, if a patient has had constipation for a long period of time, the following complications may occur
o Haemorrhoids – straining to pass stool can cause _________________, may be itchy and bleed
o Faecal impaction – hard, dry stool collects in the rectum and is extremely difficult to pass
o ___________ – liquid stool on top of faecal impaction passes around the blockage and leaks out of the anus
swollen rectal veins;
Overflow incontinence
Treatment of constipation – lifestyle and dietary modification, laxatives
- Regular physical activity
- Regular pattern of bowel movement – a regimented toilet routine should be a conditioned reflex, same time every day
o After waking proceed with mild physical activity and consume fibre cereal hot drink (preferably caffeinated) within hr of rising – visit toilet when first urge is perceived
- Adequate fluid and dietary fibre intake
o In some, fiber may worsen bloating – especially in patients with ____________), fibre increases bloating and distention, leading to poor compliance
o Fruits, vegetables, bran, nuts, prune juice in diet
- Taking advantage of known factors that stimulates defaecation (physical activity, _____________, hot fluid, caffeine and fibre) – colonic activity is the highest in the morning
- Laxatives – serotonergic agents used if no response to buking agents, osmotic and stimulant laxatives
slow transit constipation;
gastro-colic reflex
Bulking agents
- helps stool retain water
- natural/ synthetic polysaccharides or _____ derivatives
- e.g. fybogel, fibrosol
- side effects: abdominal bloating, flatulence
Osmotic laxatives
- draws water into bowel to soften stool
- poorly absorbed ions/ molecules
- eg. lactulose, ____
Stimulant laxatives
- increases bowel motility
- direct stimulatory effect _____________, increases intestinal motility
- e.g. senna, bisacodyl, _____________
- abdominal cramping or discomfort, electrolytes abnormalities, protein- losing enteropathy, melanosis coli
Serotonergic agents
- _________ agonist
- e.g. ___________
- headahce, nausea, diarrhoea, no chardiac events
cellulose;
PEG
myenteric plexus; sodium picosulfate
5HT4, Prucalopride
Osmotic diarrhoea
- An excess of osmotically active particles in lumen causes an increased, passive fluid movement into the bowel lumen down the osmotic gradient
- Presence of excess fluid exceeds the absorptive capacity of the large intestine – leads to diarrhoea as the fluid is passed rectally
- e.g. occurs with ingestion of solutes that cannot be absorbed, for example osmotic laxatives (Mg, ___, _______etc.), carbohydrate malabsorption
PO4; SO4
Secretory diarrhoea
- Excess amounts of fluid secreted due to toxin production or genetic abnormalities in enterocytes
- Often due to disruption of the sodium/chlorine channel present within the cells of the crypt
- Absorptive mechanisms become overpowered leading to diarrhoea e.g. Cholera – binding of cholera toxin A to Gαs proteins stimulate _________ to produce cAMP – activates ________________ in the membrane, causing massive Cl- efflux from the cell, creating a steep ionic and water potential gradient across the membrane, allowing Na+ and water to leave the cell
- Other examples – laxative abuse (non-osmotic laxatives), postcholecystectomy, vasculitis, drugs, disordered motility (DM autonomic neuropathy, hyperthyroidism, IBS), neuroendocrine tumours, cancers (colon CA, lymphoma), inflammatory bowel disease (can cause inflammatory/secretory diarrhoea)
adenylyl cyclase ; CFTR chloride channels
Inflammatory diarrhoea
- Inflammatory changes in the bowel wall caused by infection or autoimmune conditions
- As there is damage to the mucosal lining of the bowel wall, passive loss of ________ can occur or fluid may fail to be absorbed due to the compromised abilities of the bowel
proteins
Fatty diarrhoea
- Greasy, large volume, pale stools
- Stool fat globules and faecal fat >______(72 hrs faecal collection on 100g/d fat diet)
6g/d
- Salmonella – typhoidal and non-typhoidal (gram negative ___________ flagellate )
- Salmonella enterica serovar Typhi and Salmonella
enterica serovar Paratyphi – causes enteric fever (thyphoid)
o Common source – contaminated water/food
Stage 1: Malaise, headache, cough
Stage 2: Delirium, bradycardia, fever, _________, diarrhoea
Stage 3: Intestinal haemorrhage, perforation, septicaemia, abscesses, __________
Stage 4: Recovery phase
o Immunocompromised, elderly and young children are most at risk of developing severe illness
o Symptoms – diffuse abdominal pain, rose spots, splenomegaly, relative bradycardia
- Non-typhoidal salmonella – Salmonella enterica serovar Enteriditis and Salmonella enterica serovar Typhimurium
o Common sources – ingestion of raw or undercooked meat, poultry, eggs
o Incubation period following ingestion is 8 to 24 hours
o Symptoms include nausea, vomiting, abdominal cramps, diarrhoea can last 12 to 72 hours
rod-shaped;
rose spots; encephalitis
- Campylobacter sp. – Campylobacter jejuni (gram negative _______)
- Incubation period is 1 to 7 days with symptoms present for 1 to 7 days
- Sources – contaminated raw or undercooked poultry, unpasteurised milk, water
- Has been linked to _____________ – rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system
helical; Guillain–Barré syndrome;
Vibrio cholerae – can present with symptoms from mild to full-blown cholera (gram negative ___________ rods, highly motile)
- Faeco-oral transmission is common under impoverished and poor sanitary conditions, high infective dose with low infectivity, synthesises cholera toxins A and B
- Cholera toxins cause high volumes of fluid loss and salt loss in stool, leading to liquid stool (rice-water stool)
o Can cause onset of coma in 4 to 12 hours – patient goes into hypovolaemic shock
comma-shaped;
Escherichia coli (gram negative rod)
- Found in ______________ or poorly butchered or undercooked meat
- Pathogenesis due to toxins produced by the bacteria or through invasion of the __________
- Highly contagious, associated with outbreaks in schools and other areas with high concentrations of people, i.e. refugee camps
- Strains of E. coli o Enterotoxigenic (ETEC), enterohaemorrhagic (EHEC) i.e. 0157:H1 , enteropathogenic (EPEC), enteroinvasive (EIEC), enteroaggregative (EAEC) , diffusely adherent (DAEC)
unwashed vegetables; enterocytes
