Prolonged Diarrhoea or Vomiting

Both vomiting and diarrhoea are often self-limiting and have a benign cause and prognosis. However it is essential to make a thorough assessment to ensure there is not a more serious aetiology requiring prompt intervention. The arbitrary use of symptomatic treatments without a clear diagnosis is inappropriate. Continued vomiting and diarrhoea require further reassessment and reconsideration of the previously assumed diagnosis.

• Central:
  • Drugs, e.g. narcotics, chemotherapy
  • Acute infections, especially in children
  • Endocrine/metabolic: pregnancy, renal failure, hypercalcaemia, hypoglycaemia, hyperglycaemia (especially ketoacidosis), Addison's disease
• Gastrointestinal:
  • Inflammation, e.g. appendicitis, cholecystitis, pyelonephritis, pancreatitis, peptic ulceration, peritonitis, biliary colic
  • Obstruction, e.g. pyloric stenosis (e.g. hypertrophic pyloric stenosis in infancy), small or large bowel obstruction, severe constipation
  • Infection
  • Drugs and poisons, e.g. erythromycin, aspirin, NSAIDs, alcohol, iron, arsenic
• Central nervous system, e.g. raised intracranial pressure, labyrinthine disorders, Meniere's disease, head injury, cerebral haemorrhage, migraine
• Psychogenic, e.g. bulimia nervosa, anorexia nervosa
• Other causes, e.g. severe pain, renal tract calculi, irradiation, widespread malignant disease, acute glaucoma

There is no agreement on the duration of symptoms that define chronic as opposed to acute diarrhoea. However it is usually accepted that symptoms persisting for longer than four weeks suggest a non-infectious aetiology and therefore should be further investigated.¹

• Irritable bowel syndrome
• Colonic
  • Diverticular disease
  • Colonic neoplasia
  • Ulcerative colitis and Crohn's colitis
• Small bowel
  • Coeliac disease
  • Crohn's disease
  • Other small bowel causes include Whipple's disease, tropical sprue, amyloid and intestinal lymphangiectasia
  • Bile acid malabsorption
  • Disaccharidase deficiency, lactose intolerance
  • Small bowel bacterial overgrowth
  • Mesenteric ischaemia
  • Radiation enteritis
  • Lymphoma
• Pancreatic
  • Chronic pancreatitis
  • Pancreatic carcinoma
  • Cystic fibrosis
• Endocrine
  • Hyperthyroidism
  • Diabetes mellitus
  • Hypoparathyroidism
  • Addison's disease
  • Hormone secreting tumours (VIPoma, gastrinoma, carcinoid)
• Chronic infection, e.g. amoebiasis, giardiasis, hookworm
• Recent antibiotic therapy and Clostridium difficile infection
• Previous surgery:
  • Extensive resections of the ileum and right colon lead to diarrhoea
  • Bacterial overgrowth, particularly in bypass operations such as in gastric surgery and jejuno-ileal bypass procedures for morbid obesity
  • Shorter resections of the terminal ileum can lead to bile acid diarrhoea that typically occurs after meals and usually responds to fasting and cholestyramine
  • Chronic diarrhoea may also occur in up to 10% patients after cholecystectomy
• Drugs: up to 4% of cases of chronic diarrhoea may be due to medications (particularly magnesium containing products, antihypertensive and non-steroidal anti-inflammatory drugs, theophyllines, antibiotics, anti-arrhythmics, and anti-neoplastic agents) and food additives such as sorbitol and fructose
• Opioid withdrawal
• Alcohol: diarrhoea is common in alcohol abuse
• Immunodeficiency
• Autonomic neuropathy
• Factitious diarrhoea

• Investigation of the cause will depend on the age of the patient, presentation and associated features.
• Most important is a careful and thorough history and examination.

Vomiting investigations include

• Blood tests: full blood count, ESR, urea and electrolytes, liver function tests, amylase, glucose, calcium
• Urine: M, C and S
• Ultrasound: gallstones, liver metastases, urinary tract obstruction
• Chest x-ray (malignancy), abdominal x-ray (gastrointestinal obstruction)
• Barium meal, small bowel enema, barium enema
• Upper gastrointestinal endoscopy
• CT/MRI scan: abdominal and intracranial

Diarrhoea Investigations include

• Blood tests: full blood count (raised white cell count with infection), ESR (raised in inflammation or malignancy); urea and electrolytes, liver function tests, thyroid function tests. Specific investigations for rare causes may include serum gastrin (Zollinger-Ellison syndrome), calcitonin (medullary carcinoma of thyroid) or vasoactive intestinal peptide (VIPoma).
• Stool: M, C and S; faecal fats (malabsorption)
• Ultrasound: liver metastases
• Barium enema, small bowel enema
• Sigmoidoscopy, colonoscopy
• Biopsy: rectal biopsy (Crohn's), in association with colonoscopy (e.g. ulcerative colitis), jejunal biopsy (coeliac disease)

• Correction of fluid and electrolyte imbalance.
• Treatment of any underlying cause.
• Symptomatic treatment should only be used as part of a management plan with a definite diagnosis of the cause of the vomiting and/or diarrhoea.

• Prolonged vomiting may cause:
  • Dehydration
  • Metabolic alkalaemia, hyponatraemia, and hypokalaemia
  • Haematemesis from a Mallory-Weiss tear of the oesophagus.
• Prolonged diarrhoea may cause:
  • Dehydration
  • Hypokalaemia