Assess clinical state. Rehydration is key. Altered bowel habit may suggest colorectal cancer. Causes are mainly infective, ischaemic and malignant and context will help
About
- Increased stool output > 200 g/day
- Increased stool fluid content and frequency
- Chronic diarrhoea when lasts > 3 weeks
- Steatorrhoea is > 7g fat per day in stools on a high-fat diet
Clinical
- Watery stools, mucus, abdominal cramping pain
Causes
- Infectious agents
- Gastroenteritis
- Antibiotic-associated colitis
- Protozoa: usually persists > 5 days
- Giardia
- Amoebiasis (bloody stools)
- Cryptosporidium
- Microsporidiosis
- Isosporiasis
- Bacterial
- Shigella (enteroinvasive with bloody stool)
- Campylobacter(enteroinvasive with bloody stool)
- C. difficile
- Salmonella
- Enterotoxigenic E. coli
- Enterohaemorrhagic E Coli (enteroinvasive with bloody stool)
- Enteroinvasive E. coli
- Vibrio cholerae
- Toxin Mediated: usually < 18 hrs
- Bacillus cereus
- Clostridium spp. enterotoxin
- Staph. aureus
- Acute diverticulitis
- Sepsis
- Pelvic inflammatory disease,
- Meningococcaemia
- Atypical pneumonia
- Malaria
- Inflammatory
- Ulcerative colitis (bloody)
- Crohn's disease
- Functional - Irritable bowel syndrome
- Osmotic - oral intake of unabsorbed sugars
- Drug induced - laxatives, colchicine, PPIs
- Malabsorption
- Pancreatic insufficiency
- Coeliac disease
- Crohn's disease
- Neoplastic
- Colorectal (bloody)
- Rectal villous adenoma (mucus)
Red flags
- Low blood pressure, pulse state of hydration
- Bloody diarrhoea and high stools frequency
- Abdominal signs - tender, guarding
- Weight loss, Acute Kidney injury, Haematuria
Causes of Bloody Diarrhoea
- Ulcerative colitis/Crohn's disease
- Colorectal cancer, Colorectal polyps
- Ischaemic colitis, Diverticular disease
- Pseudomembranous colitis
- Schistosomiasis, Yersinia enterocolitica
- Salmonella, Shigella, E.Coli, Campylobacter
- Amoebiasis (Entamoeba histolytica)
- Coagulopathy
Investigations
- Assess stool with Bristol stool scale
- Stool microscopy and culture, ova cysts and parasites
- Clostridioides difficile toxin
- Check U&E for dehydration. In children consider Haemolytic uraemic syndrome with certain E coli with bloody diarrhoea
- FBC - elevated WCC, Anaemia - Microcytic suggests possibly a colonic malignancy or inflammatory bowel disease. Macrocytosis may be suggested by malabsorption. Dimorphic may suggest both.
- LFTS - elevated ALP and Bilirubin with obstruction may cause steatorrhoea
Management
- Isolation is generally key if there is any suggestion of an infective cause
- ABC, Oral rehydration therapy. IV fluids may be needed in some
- Avoid antibiotic especially in those at risk of Haemolytic uraemic syndrome