Diarrhoea Flashcards
What is the definition of diarrhoea
Increasing the amount of stool passed to over 300g of stool per day (often accompanies by increased frequency and loosening)
What are the causes (general) of diarrhoea
Infection
Inflammation - IBD, diverticular
Increased motility - hyperthyroidism, anxiety, IBD
Malabsorption - coeliac, pancreatic insufficiency
Obstruction that only allows liquid stool - constipation (overflow diarrhoea), colon/ovarian cancer
Medications
What medications can cause diarrhoea
Laxatives Colchicine Digoxin Metformin Thiazide diuretics Antibiotics
What are the most likely causes of diarrhoea in a young patient (18yrs)
Infectious diarrhoea IBS Coeliac Crohn's UC Medications
What are the most likely causes of diarrhoea in an elderly patient
Neoplastic disease e.g. villous polyps, colonic adenocarcinoma, pancreatic cancer
Diverticular disease overflow diarrhoea Ischaemic colitis Microscopic colitis bacterial overgrowth UC
What are the concerns in a patient who has presented with a couple days diarrhoea and how should this be managed
Dehydration
Electrolyte imbalance - excessive loss of K+ or HCO3- OR hypovolaemia + ischaemia -> Hyperkalaemia
Metabolic acidosis - gain of acid or loss of base or both, high anion gap suggests ischaemia -> anaerobic glycolysis -> lactic acidosis
How do you acutely manage a patient who has had a couple days history of hypovolaemia
Rehydrate by establishing IV access and administering fluid challenge 500mL and continue until BP rises
What questions should be asked about diarrhoea
Characterise diarrhoea - consistency and colour Frequency/bowel habit Associated symptoms Risk factors Family history
What questions should be asked to characterise the stool in diarrhoea and what do the answers suggest
Mucoid or jelly like? (classically salmonella or villous polyps)
Foul smelling and floating? (malabsorption - coeliac, pancreatic duct obstruction, biliary insufficiency)
Are the faeces unusually pale? (lack of bile salts due to duct obstruction e.g. chronic pancreatitis, gallstones)
Is there any blood? - describe it (on the paper/streak - anal path)(red and mixed in - colorectal e.g. U, dysentery, carcinoma)
What should be asked about bowel habit with diarrhoea and what do the answers suggest
Nocturnal?
Do you have to rush to pass motions ? - infectious or IBD
Is there a feeling of incomplete emptying? - carcinoma
Has habit been variable? - IBS, carcinoma
How often/has this happened before? (infection vs chronic)
What associated symptoms should be asked about for diarrhoea and what do they suggest
Vomiting? - infectious
Abdominal pain? Crohn’s, yersinia infection, diverticular D, IBS (relieved by passing)
Significant weight loss - IBD, carcinoma
Eye problems, joint pains, skin rashes - IBD
What are the extra-GI manifestations of IBD
Uveitis (painful red eye with loss of vision)
Scleritis (painful red eye with no loss of vision)
Episcleritis (uncomfortable red eye, no loss of vision)
Enteric arthritis
Erythema nodosum (painful, dark red nodules on shins)
Pyoderma gangrenosum (ulcers with a surrounding purple halo)
What risk factors should be asked about when asking about diarrhoea
Recent travel
Eaten unusal foods
DO others she knows have similar symptoms
Stressed lately (IBS)
how is the diet - particularly fibre (IBS)
Medications
What should be looked for on examination of a patient with diarrhoea
Clubbing Iritis, episcleritis, scleritis Mouth ulcers Erythema nodosum Dermatitis herpetiformis Virchow's lymphadenopathy Abdominal masses Anal fissure or fistulae DRE
What do the following features on examination suggest
Clubbing: Crohn’s, UC, hyperthyroidism, coeliac
Iritis, episcleritis, scleritis: Crohn’s/UC
Mouth ulcers: Crohn’s
Erythema nodosum: Crohn’s/UC + COCP use
Dermatitis herpetiformis: coeliac
Virchow’s lymphadenopathy: bowel malignancy
Abdominal masses: RLQ - crohn’s; Malignancy
Anal fissure or fistulae: Crohn’s
What blood tests should be arranged for a patient with diarrhoea
FBC (anaemia, raised WBC, platelet count): IBD/coeliac -> B12/iron/folate malabs -> anaemia; UC -> blood loss
ESR and CRP: IBD, infectious (CRP only)
tTG and IgA levels: coeliac
TFTs: hyperthyroidism
U+Es: dehydration assessment or electrolyte disturbance
Albumin: low in chronic diarrhoea
Capillary glucose: diabetes
what tests should be done on the stool for diarrhoea
Microscopy and culture: infection
C. difficile toxin test (if recent antibiotic use)
Occult blood test (FOBT): UC, infection
What differentiates presentation of infectious diarrhoea vs food poisoning
Food poisoning (presence of toxins) usually presents with onset within hours of consuming a meal Often s. aureus or bacillus cereus
What is the acute management for food poisoning
Oral rehydration, consider oral rehydration salts
What is the management of IBS
Reassurance that there is no serious path
Antispasmodics: mebeverine, hycosine; severe -> loperamide
Antidepressants: TCAS e.g. amitriptyline
Diet and herbal remedies
Diet: avoidance of triggers, increase fibre, herbal
What is the immediate management of suspected C.diff colitis
- ABC - check for hypovolaemia and dehydration -> IV fluid resus (250ml boluses of IV crystalloid)
- Faeces analysis - send sample for MC+S immediately
- Isolation
- Meticulous hygiene for all those in contact using SOAP
- Antibiotics: oral metronidazole
- Review medications or address precipitants to infection
What extra management step is taken in severe c. diff
Oral vancomycin
Regular AXR, lactate measurements and daily surgical review to mitigate against toxic colon and perforation
What are the complications that are more associated with UC rather than Crohn’s
Colonic carcinoma
Primary sclerosing cholangitis
Cholangiocarcinoma
What is the management of UC
Medical: salicylate derivatives - sulfasalazine, mesalazine; methotrexate, azathioprine, corticosteroids, anti-TNF Abs
Monitoring: regular colonoscopy, AXR in severe cases to assess for toxic megacolon
Surgical therapy: Removal of affected bowel and ileostomy formation
What investigations should be done for overflow diarrhoea with faeces that tests positive for blood
Suggests colorectal carcinoma
Flexible sigmoidoscopy or rigid proctosigmoidoscopy
+biopsy
Double contrast barium enema to look for the apple core sign
What are the extra-GI signs of Crohn’s
Nails: clubbing
Eyes: iritis (anterior uveitis), episcleritis, scleritis
Skin: erythema nodosum, pyoderma gangrenosum
Joints: enteric arthritis
Blood: IDA, vit B12/folate deficiency
Biliary: PSC, cholesterol gallstone
Kidneys: kidney stones
Bones: osteomalacia or osteoporosis
Amyloidosis
What is the most likely infective organism in an outbreak of vomiting and diarrhoea in an old person’s nursing home
Small structured round virus (SSRV) type e.g. norovirus
What is the most likely infective organism in an outbreak of bloody diarrhoea at a local primary school
Dysentery associated with shigella or E. coli O157
What is the most likely infective organism in an a university student with water diarrhoea a few days after a barbecue
Camplylobacter jejuni
What is the most likely infective organism in a group of guests with sudden-onset diarrhoea a few hours after a wedding reception
S. aureus and bacillus cereus
rapid onset - meal contaminated with bacteria with pre-formed active toxins
What is the most likely infective organism in an 82 year old man receiving antibiotics for pneumonia
C. diff
What is the most likely infective organism in a young woman who has just returned from Ghana and has RIF pain and diarrhoea
Traveller’s = E. coli
However, RIF pain = Yersinia enterocolitica
What is a fluid challenge
IV bolus of 150-500mL crystalloid over 30 minutes to a hypovolaemic patient
Once given, re-assess the patient
NO response: not enough fluids or NOT hypovolaemic - re-assess and repeat
Transient response: haven’t given enough or patient is losing them rapidly e.g. haemorrhage -> give more fluids
Sustained response: They have been restored
What are maintenance fluids
Maintenance needed to restore the daily loss
Need 2.5L fluid, 100mM sodium and 70mM potassium
How much fluid in an adult
2.5L in urine , faeces and insensible losses (sweating, respiration ~800ml)
What are replacement fluids and what are the common requirements
Required in patient with conditions that result in abnormally high fluid loss
Fever: extra 500mL for every degree above 37
Burns: Parkland formula calculation
Stoma: measure and record fluid loss in the stoma bag
Third spacing: trial and error
What must always be done with any patient receiving IV fluids
Document fluid input/output and re-assess the patient clinically and biochemically (electrolyte disturbance)
What signs signify that a patient is not receiving enough fluid
Thirsty Dry mucous membranes Tachycardia Narrow pulse pressure Urine output <30 mL/h
What signs dignify a patient is receiving too many fluids
Puffy (oedematous)
Crackles in lung bases
Raised JVP
