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Diarrhoea
Definition: Abnormal passage of loose or liquid
stools more than 3 times daily and/or a
volume of stool greater than 200g/day (British
Society of Gastroenterology)
Acute diarrhoea: < 4 weeks, usually self-limiting
Chronic diarrhoea: > 4 weeks
Pathophysiology
1) Increased osmotic load in the gut lumen
(osmotic diarrhoea)
2) Increase in secretion (secretory diarrhoea)
3) Inflammation of the intestinal lining ie IBD
4) Increased intestinal motility
Can involve more than 1 mechanism!
Causes of diarrhoea
Acute
Chronic
Bacterial and viral infection ie Salmonella, Infection: (less likely to be chronic)
E.coli, Cl. Difficile
Drugs ie allopurinol, Ang II receptor
blocker, antibiotics, digoxin, NSAIDs, PPI,
SSRI, statins
Functional: Irritable bowel syndrome
Anxiety
Diet: Lactose intolerance
Food Allergy
Inflammation: IBD – UC, Chron’s
Acute appendicitis
Surgery: intestinal/gastric
bypass/resection
Acute radiation enteritis
Malabsorption syndrome: Coeliac
disease, pancreatic insufficiency
Intestinal ischemia – assess CVS risk
Tumors: colorectal carcinoma, lymphoma,
endocrine tumor: VIPoma, gastrinoma,
carcinoid
Endocrine: Hyperthyroidism
Infective Gastroenteritis
According to Health Protection Agency and Health
Protection Scotland: Most common cause:
Causal agent
Description
Campylobacter (46%)
-transmit through raw, undercooked meat esp poultry, incubation
period 2-5 days, bloody diarrhea, abdominal pain, vomiting
(uncommon), possible toxic megacolon
Rotavirus (19%)
-most common cause of childhood diarrhoea, watery diarrhoea
Norovirus (14%)
-outbreaks are difficult to contain, transmit by aerosol & faecal
oral,, watery diarrhoea, identify the virus doesn’t alter the
management
Salmonella (12%)
-transmit from red and white meats, raw or undercooked eggs,
milk, dairy products, or person to person. Watery diarrhoea,
vomiting, fever
E.Coli (2%)
-Shiga toxin producing E.coli (STEC), transmit from undercooked
ground beef, water, cross contamination of cooked
products,has potentially serious complication esp HUS, range
from mild diarrhoea to haemorrhagic colitis, severe abdominal
pain
Enterotoxigenic E.coli, transmit by feacally contaminated food
or water, causes watery diarrhoea
Shigella (1%)
-can cause bloody diarrhoea
Acute dysentry = frequent, small bowel movements, accompanied by blood and mucous
with tenesmus or pain on defeacation
WHY?
Invasive bacteria (most likely Campylobacter, Shigella, STEC) causes inflammatory
invasion of colonic mucosa. Feacal leukocytes are present.
What about watery diarrhoea?
- usually typical of small intestinal infection, non-inflammatory
process , confirmed by absence of feacal leukocytes
- mediated by bacterial endotoxins that alter fluid and electrolyte
transport ie:
• Vibrio cholerae: transmit through contaminated water/seafood,
rice water stool
• Cl. Difficile: usually due to antibiotics ~4-9 days (ie ampicillin,
amoxicillin), varies from mild watery diarrhoea to severe bloody
diarrhoea. Complications include hypovolemic shock, toxic
megacolon, perforation, haemorrhage, sepsis, eradicate using
metronidazole, and withdraw other antibiotics!
• Enterotoxigenic E.coli, Salmonella, Cryptosporidium,
Cl.perfringen, Bacillus cereus, Giardia lamblia, rotavirus,
norovirus
Red flag signs for Diarrhoea!!!
1) Unintentional and unexplained weight loss
2) Rectal bleeding
3) Diarrhoea persisting for more than 6
weeks, in a person over 60 years of age
4) Family history of bowel or ovarian cancer
5) Abdominal mass
6) Rectal mass
7) Anaemia
8) Raised inflammatory markers (may indicate
inflammatory bowel disease).
Investigation
1) Full blood count — to detect anaemia or raised platelet count
suggesting inflammation
2) Blood culture if its infective cause
3) Liver function tests, including albumin level.
4) Tests for malabsorption:
Calcium.
Vitamin B12 and red blood cell folate.
Iron status (ferritin).
5) Thyroid function tests.
6) ESR & CRP — elevated levels may indicate IBD
7) Antibody testing for coeliac disease — immunoglobulin (Ig)A
tissue transglutaminase antibody (tTGA), or IgA endomysial
antibody (EMA).
Investigation
Consider sending stool for culture and sensitivity and
examination for ova, cysts and parasites, if an infectious cause is
suspected or there is a history of travel to high-risk areas.
Send three specimens (5 mL each) 2–3 days apart, as ova,
cysts, and parasites are shed intermittently.
Management
Treat the cause!
1) Oral rehydration (better than IV), if impossible
give 0.9% saline + 20 mmol K+/L IVI
2) Codeine phosphate 30mg/6 hrs
3) Loperamide 2mg PO
4) Avoid antibiotics except in infective diarrhoea
causing systemic illness
Definition of constipation:
= difficult or infrequent passage of stool ( <3x a
week) , hardness of stool, or a feeling of
incomplete evacuation.
Absolute constipation:
Failure to pass any stools.
Types of constipation:
1) Functional/primary/idiopathic constipation =chronic
constipation without a known cause
2) Secondary/organic constipation - caused by medical
conditions or drugs ie opioids, TCA, antispasmodic,
calcium supplement, aluminium antacids
3) Faecal loading/impaction
4) Overflow incontinence/ bypass soiling/encopresis
leakage of loose stool around impacted faeces.
Pathophysiology
1) Colonic inertia (reduced bowel movement)
2) Outlet delay constipation (or obstructed
defecation) which can be caused by pelvic
floor dyssynergia (the pelvic floor muscles
contract or fail to relax during attempted
defecation), and by anismus (the external
anal sphincter contracts instead of relaxing
during attempted defecation
Causes of Constipation
Acute constipation
Bowel
Volvulus, hernia, adhesions, fecal
obstruction
impaction
Adynamic ileus Peritonitis, major acute illness
(eg, sepsis), head or spinal
trauma
Anticholinergics (eg, antihistamines,
Drugs
antipsychotics, antiparkinsonian
drugs, antispasmodics), cations (iron,
aluminum, Ca, barium, bismuth),
opioids, Ca channel blockers, general
anesthesia
Chronic constipation
Colonic tumor
Adenoca of sigmoid colon
Metabolic
DM, hypothyroidism, hypocalcemia or
disorders
hypercalcemia, pregnancy, uremia,
porphyria
CNS disorders
Parkinson's disease, MS , stroke, spinal
cord lesions
Peripheral
Hirschsprung's disease,
nervous system neurofibromatosis, autonomic
disorders
neuropathy
Systemic
Systemic sclerosis, amyloidosis,
disorders
dermatomyositis, myotonic dystrophy
Functional
Slow-transit constipation, irritable bowel
syndrome, pelvic floor dysfunction
(functional defecatory disorders)
Predisposing factors
1) Social factors: Low fibre diet
2) Lifestyle: Difficult access to toilet, or changes
in routine/lifestyle, Lack of exercise; reduced
mobility.
3) Psychological: Anxiety, Depression,
Somatization, Eating disorders
4) Physical: Mild pyrexia, dehydration,
immobility.
RED FLAGS FOR CONSTIPATION!
1)
2)
3)
4)
5)
6)
7)
Persistent unexplained change in bowel habits?
Palpable mass
Persistent rectal bleeding without anal symptoms
Distended, tympanitic abdomen
Vomiting
Family history of colon cancer, IBD
Unexplained weight loss, iron deficiency anaemia,
fever, or nocturnal symptoms
8) Severe, persistent constipation that is unresponsive
to treatment
How to interpret clinical findings:
1)Abdominal pain
2)Vomiting
3)Abdominal distention
4)Progress of condition
5)Sigmoid volvolus
6)Ischemia/perforation
7)Pseudo obstruction
How to interpret clinical findings:
How to differentiate Intestinal Obstruction & paralytic
Ileus ?
IO – partial  active, tinkling bowel sounds
complete  absent bowel sounds & absent flatus,
usually severe vomiting
PI – absent bowel sounds & flatus is present
SO?
Radiology!
Small bowel obstruction
Gallstone ileus
-multiple dilated
small bowel
Throughout
SMALL  ALL
->3cm is abnormal
-valvulae
conniventes
-paucity of gas in
bowel beyond site
of obstruction
Paralytic ileus
• White arrow –
multiple dilated
small bowel loops
• Black arrowsurgical staples
To differentiate small bowel
obstruction and paralytic ileus
• CT scan to exclude any obstruction, if there’s
no obstruction, check medical history:
ie previous surgery or electrolyte imbalance
such as hypo/hyperkalemia, hypocalcemia,
hypomagnesemia  indicates paralytic ileus
Large Bowel Obstruction
Colon Ca
-dilated bowel
loops proximal
to obstruction
-dilated large
bowel loop
>6cm
Investigations
Depends on clinical findings:
1) Constipation with a clear etiology (drugs, trauma) may be treated
symptomatically without further study.
2) Blood tests: FBC, U&E, Ca2+, TFT
If suspected malignancy, proceed with:
4) Abdominal X-ray
5) Sigmoidoscopy and biopsy of abnormal mucosa
6) Colonoscopy
7) Water soluble contrast enema
8) CT Scan or barium X-ray
Management
1) Adjust any constipating medication, if possible.
2) Increasing dietary fibre, drinking an adequate fluid intake,
and exercise
3) Offer oral laxatives if dietary measures are ineffective, or
while waiting for them to take effect.
1) Bulk-forming laxative ie ispaghula husk, methylcellulose,
sterculia, frangula
2) Osmotic laxative ie lactulose, macrogols (polyethylene
glycols)
3) Stimulant laxative ie bisacodyl, senna, sodium
picosulfate
• Laxatives can be stopped once the stools become soft and easily passed
again
Questions
1)
2)
3)
4)
A 20 year old girl presents with abdominal pain and recently up to 15 bouts of
diarrhoea containing blood and mucus. Her stool culture is negative IBD
A 23 year old medical student is on elective in Thailand, when he develops
cramping abdominal pain and a watery diarrhoea after drinking the local water.
It is self limiting and resolves after few days Entero E.coli
A 36 year old woman presents with weight loss, general abdominal discomfort
and steatorrhoea. On examination she appears pale and malnourished. Gastric
ca
A 36 year old woman presents with abdominal pain and an acute watery
diarrhoea containing blood. She has no significant PMH apart from a recent
pneumonia which was treated with amoxicillin Cl.difficile
A: chronic gastritis
B: Cl. Difficile infection
C: IBD
D: gastric ca
E: Enterotoxigenic E.coli
F: ischaemic colitis