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.

Vomiting

There are separate articles on Nausea and Vomiting in Palliative Care, Persistent Nausea or Vomiting, Nausea and Vomiting in Pregnancy - Including Hyperemesis, Dyspepsia and Treatment of Nausea and Vertigo.

Clinical assessment

• The main priorities on assessment include the presence and degree of dehydration (especially in infants, young children and the elderly) and the underlying cause, particularly any possibility of a serious underlying cause requiring urgent admission or referral.
• Associated headache may occur with migraine but meningitis, subarachnoid haemorrhage and raised intracranial pressure also need to be considered.
• Abnormal clinical signs in the abdomen may include localised pain, tenderness and guarding (e.g. acute appendicitis, acute cholecystitis) or absent bowel sounds (acute gastrointestinal obstruction).
• Associated anorexia and weight loss indicate possible malignancy.
• Vomiting blood may indicate peptic ulcer disease, Mallory-Weiss tear, oesophageal varices, gastro-oesophageal reflux disease, or malignancy.
• Genitourinary causes should be considered, e.g. testicular torsion or acute epididymitis in men, and ruptured ovarian cyst or ovarian torsion in women.
• Pregnancy in women, medication, occupation and recent travel should also be considered in the assessment of the cause for the vomiting.

Investigations

• Blood tests: full blood count, ESR or CRP, renal function and electrolytes, liver function tests, amylase, glucose, calcium
• Urine: urinalysis, microscopy and culture, pregnancy test
• Further assessment for possible underlying infection may include stool cultures, blood cultures, lumbar puncture
• 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

Complications

Severe or persistent vomiting may cause:

• Dehydration
• Metabolic alkalaemia, hyponatraemia, and hypokalaemia
• Haematemesis from a Mallory-Weiss tear of the oesophagus

Diarrhoea

There are separate articles on Childhood Diarrhoea, Chronic Diarrhoea in Adults, Gastroenteritis in Adults and Older Children, Travellers' Diarrhoea, Faecal Incontinence and Rectal Bleeding

Clinical assessment

• The main principles for assessment are the same as for vomiting, i.e. assessment of dehydration, excluding a serious cause and making a specific diagnosis to enable specific treatment.
• It is essential to make an assessment of the degree of diarrhoea, as there is considerable variation in normal bowel habit and patient perception.
• Associated weight loss usually indicates a serious underlying cause, e.g. inflammatory bowel disease or malignancy.
• Constipation with overflow should be considered, especially in the elderly.
• Occupation and recent foreign travel may be important in terms of indicating a cause for the diarrhoea.

Investigations

• Blood tests: full blood count (raised white cell count with infection), ESR (raised in inflammation or malignancy); renal function 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 polypeptide-secreting tumour (VIPoma).
• Stool: microscopy, culture and sensitivities; faecal fats (malabsorption)
• Ultrasound/CT scan: liver metastases
• Barium enema, small bowel enema
• Proctoscopy, sigmoidoscopy, colonoscopy
• Biopsy: rectal biopsy (Crohn's disease), in association with colonoscopy (e.g. ulcerative colitis), jejunal biopsy (coeliac disease)

Complications

Prolonged diarrhoea may cause:

• Dehydration
• Hypokalaemia

Management

General principles of management of vomiting or diarrhoea

• Refer urgently if significant dehydration or possible serious underlying cause (e.g. acute admission for patient with an acute abdomen or serious infective cause; urgent referral for possible malignancy).
• People with diabetes are at particular risk of dehydration and electrolyte imbalance, and so should have a lower threshold for hospital admission.
• Correction of fluid and electrolyte imbalance.
• Diagnosis and specific 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.

Internet and further reading

• Kinirons M, Ellis H; French's Index of Deifferential Diagnosis. 14th edition.

Acknowledgements