DIARRHOEAAND
CONSTIPATION
DiarrhoeaDefinition: 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
Pathophysiology1) 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 motilityCan involve more than 1 mechanism!
Causes of diarrhoeaAcute ChronicBacterial and viral infection ie Salmonella, E.coli, Cl. Difficile
Infection: (less likely to be chronic)
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 painEnterotoxigenic 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 loss2) Rectal bleeding3) Diarrhoea persisting for more than 6
weeks, in a person over 60 years of age4) Family history of bowel or ovarian cancer5) Abdominal mass6) Rectal mass7) Anaemia8) Raised inflammatory markers (may indicate
inflammatory bowel disease).
Investigation1) Full blood count — to detect anaemia or raised platelet count suggesting inflammation2) Blood culture if its infective cause3) 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 IBD7) Antibody testing for coeliac disease — immunoglobulin (Ig)A tissue transglutaminase antibody (tTGA), or IgA endomysial antibody (EMA).
InvestigationConsider 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 hrs3) Loperamide 2mg PO 4) Avoid antibiotics except in infective diarrhoea
causing systemic illness
CONSTIPATION
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.
Pathophysiology1) 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 ConstipationAcute constipationBowel obstruction
Volvulus, hernia, adhesions, fecal impaction
Adynamic ileus Peritonitis, major acute illness (eg, sepsis), head or spinal trauma
Drugs Anticholinergics (eg, antihistamines, antipsychotics, antiparkinsonian drugs, antispasmodics), cations (iron, aluminum, Ca, barium, bismuth), opioids, Ca channel blockers, general anesthesia
Chronic constipation Colonic tumor Adenoca of sigmoid colonMetabolic disorders
DM, hypothyroidism, hypocalcemia or hypercalcemia, pregnancy, uremia, porphyria
CNS disorders Parkinson's disease, MS , stroke, spinal cord lesions
Peripheral nervous system disorders
Hirschsprung's disease, neurofibromatosis, autonomic neuropathy
Systemic disordersSystemic sclerosis, amyloidosis, dermatomyositis, myotonic dystrophy
Functional Slow-transit constipation, irritable bowel syndrome, pelvic floor dysfunction (functional defecatory disorders)
Predisposing factors
1) Social factors: Low fibre diet2) 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) Persistent unexplained change in bowel habits?2) Palpable mass 3) Persistent rectal bleeding without anal symptoms4) Distended, tympanitic abdomen5) Vomiting6) Family history of colon cancer, IBD7) Unexplained weight loss, iron deficiency anaemia,
fever, or nocturnal symptoms8) Severe, persistent constipation that is unresponsive
to treatment
How to interpret clinical findings:
1)Abdominal pain2)Vomiting3)Abdominal distention4)Progress of condition5)Sigmoid volvolus6)Ischemia/perforation7)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 obstructionGallstone ileus-multiple dilated small bowel ThroughoutSMALL 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 arrow- surgical 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
InvestigationsDepends 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-ray5) Sigmoidoscopy and biopsy of abnormal mucosa6) Colonoscopy7) Water soluble contrast enema8) CT Scan or barium X-ray
Management1) Adjust any constipating medication, if possible.2) Increasing dietary fibre, drinking an adequate fluid intake,
and exercise3) 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, frangula2) 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
Questions1) 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 IBD2) 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
3) A 36 year old woman presents with weight loss, general abdominal discomfort and steatorrhoea. On examination she appears pale and malnourished. Gastric ca
4) 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 gastritisB: Cl. Difficile infectionC: IBDD: gastric ca E: Enterotoxigenic E.coliF: ischaemic colitisG: Colorectal CaH: Cholera