Gastroenterology & Hepatology
Question 67 of 73
A 72 year old man is brought to the Emergency Department by carers from his nursing home. They have noted that he has not opened his bowels for 8 days until this morning when he passed liquid stool. They are concerned as there has been a recent outbreak of norovirus gastroenteritis at the facility. The patient has a past medical history of a cerebral vascular accident that has left him bed-bound. On examination you note hard stool in the rectum. What is the most likely diagnosis?
Answer:
Constipation is common and can be a very debilitating condition in the elderly population. It can present with pain and discomfort and is more common in people who are immobile for long periods of time or on multiple painkillers. Spurious diarrhoea such as described can occur as watery stool manages to escape around the impacted faeces, often giving a mixed picture of diarrhoea on the background of constipation. Treatment for constipation begins with lifestyle, increasing the amount of fluid drunk, encouraging mobilisation where possible and withholding or changing constipating drugs such as opiates. Pharmacological treatments include osmotic laxatives such as lactulose, which draw water into the stool, a bulk forming laxative such as bran, and stimulant laxatives such as movicol or glycerine suppositories.Diarrhoea
Gastroenterology & Hepatology / Surgical Emergencies
Last Updated: 12th February 2021
Diarrhoea is a symptom, of which there are many causes. Many different definitions of diarrhoea have been suggested, but the World Health Organization defines diarrhoea as 'the passage of three or more loose or liquid stools per day (or more frequent passage than is normal for the individual)'. Acute diarrhoea is defined as lasting for less than 14 days, persistent diarrhoea is defined as lasting more than 14 days and chronic diarrhoea is defined as lasting more than 4 weeks.
Mechanisms of diarrhoea
- Osmotic diarrhoea
- Osmotic diarrhoea occurs when a soluble compound cannot be absorbed by the small intestine, and thus draws fluid into the intestinal lumen. Examples include: osmotic laxatives; magnesium-based antacids; and foods containing mannitol, sorbitol, or xylitol. Osmotic diarrhoea can also be due to generalised malabsorption (for example, coeliac disease and pancreatic insufficiency).
- Secretory diarrhoea
- Secretory diarrhoea results from increased secretion of fluid and electrolytes into the intestine with decreased absorption. Infections with such organisms as Vibrio cholerae, E. Coli, and C. difficile can cause secretory diarrhoea, as can bile salts in the colon (for example, after ileal resection) some drugs (for example, laxatives, diuretics, theophylline, cholinergic drugs, prostaglandins, caffeine, and ethanol) and gut allergies.
- Inflammatory diarrhoea
- Damage to intestinal mucosal cells affects absorption of fluid and electrolytes and results in fluid and blood loss. Infection (for example, Shigella) and conditions such as ulcerative colitis and Crohn's disease are causes of inflammatory diarrhoea.
- Increased intestinal motility
- This may present with an increased frequency of stool passage without an increase in volume. It can occur with endocrine conditions such as diabetes and hyperthyroidism.
Causes
Causes of acute diarrhoea:
- Infection
- Viruses
- Norovirus, sapovirus, rotavirus
- Bacterial causes
- Salmonella species, Campylobacter jejuni, Shigella species, Escherichia coli and Clostridium difficile
- Parasitic causes
- Cryptosporidium, Giardia, Entamoeba histolytica, and Cyclospora
- Viruses
- Drugs
- Laxatives, allopurinol, angiotensin-II receptor blockers, antibiotics, chemotherapy, magnesium-containing antacids, metformin, nonsteroidal anti-inflammatory drugs, proton pump inhibitors, and selective serotonin reuptake inhibitors
- Other causes
- Anxiety
- Food allergy
- Acute appendicitis
- Pelvic radiation treatment
- Intestinal ischaemia
- Early presentation of a chronic cause (for example, a first presentation of inflammatory bowel disease)
Common causes of chronic diarrhoea:
- Irritable bowel syndrome
- Diet
- Inflammatory bowel disease (Crohn's disease, ulcerative colitis).
- Microscopic colitis
- Coeliac disease
- Other causes of malabsorption e.g. lactose intolerance and pancreatic insufficiency
- Colorectal cancer
- Bile acid diarrhoea
- Drugs
- Constipation and faecal impaction (leading to overflow)
Assessment
- Determine the onset, duration, frequency, and severity of symptoms.
- Enquire about the presence of red flag symptoms:
- e.g. blood in stool, recent hospital treatment or antibiotics, weight loss, evidence of dehydration
- Attempt to ascertain the underlying cause:
- Features suggesting infection include:
- Fever
- Vomiting
- Recent contact with a person with diarrhoea
- Exposure to possible sources of enteric infection (for example, having eaten meals out, or recent farm or petting zoo visits)
- Travel abroad — increases the likelihood of infection. Ask about potential exposures such as raw milk or untreated water
- Being in a higher risk group such as food handlers, nursing home residents, and recently hospitalised people
- Features suggesting infection include:
- Assess for complications of diarrhoea, such as dehydration
- See table below
- Perform an abdominal examination to assess for pain or tenderness, distension, mass, increased or decreased bowel sounds, or liver enlargement.
- Consider a rectal examination to assess for rectal tenderness, stool consistency, and for blood, mucus, and possible malignancy.
| Mild dehydration | Moderate dehydration | Severe dehydration |
|---|---|---|
|
|
|
| Usually no signs |
|
|
Investigations
- Send a faecal specimen for routine microbiology investigation if a person with diarrhoea has:
- Symptoms/signs or a clinical indication:
- The person is systemically unwell; needs hospital admission, and/or antibiotics.
- There is blood or pus in the stool.
- The person is immunocompromised.
The person has recently received antibiotics, a proton pump inhibitor (PPI) or been in hospital — also request specific testing for Clostridium difficile. - Diarrhoea occurs after foreign travel — also request tests for ova, cysts, and parasites and state the countries visited on the form.
- Amoebae, Giardia, or cryptosporidium are suspected, particularly if diarrhoea is persistent (2 weeks or more) or the person has travelled to an at-risk area.
- There is a need to exclude infectious diarrhoea (for example severe abdominal pain, exacerbation of inflammatory bowel disease, or irritable bowel syndrome).
- A public health indication:
- Diarrhoea in high-risk people (for example food handlers, healthcare workers, elderly residents in care homes).
- Suspected food poisoning (for example after a barbeque, restaurant meal, or eating eggs, chicken, or shellfish).
- Outbreaks of diarrhoea in the family or community, when isolating the organism may help pinpoint the source of the outbreak.
- Contacts of people infected with certain organisms, for example, Escherichia coli O157 or C. difficile, where there may be serious clinical sequelae to an infection.
- Close household contacts of a person with Giardia infection.
- Symptoms/signs or a clinical indication:
- Diagnostic tests that may be considered in the diagnostic evaluation of acute diarrhoea in people with severe illness are:
- FBC. This can help with assessing the severity of the diarrhoea (look for haemoconcentration, anaemia, and leucocytosis with left shift)
- Serum chemistry. Electrolytes, urea nitrogen, and creatinine (look for hypokalaemia, acidosis, and renal dysfunction). Serum albumin and lactic acid (look for low albumin or elevated lactic acid)
- Consider blood tests if infection and the other causes of acute diarrhoea have been excluded and it is suspected that an episode of acute diarrhoea is due to a chronic cause.
- Full blood count — to detect anaemia.
- Urea and electrolytes.
- Liver function tests, including albumin level.
- Calcium.
- Vitamin B12 and red blood cell folate.
- Iron status (ferritin).
- Thyroid function tests.
- ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein).
- Testing for coeliac disease — immunoglobulin A (IgA), and IgA tissue transglutaminase (tTG), or IgA endomysial antibody (EMA).
Management
- Arrange emergency admission to hospital if:
- The person is vomiting and unable to retain oral fluids, or
- They have features of severe dehydration or shock
- Other factors that influence the threshold for admission include (use clinical judgment):
- Older age (people 60 years of age or older are more at risk of complications).
- Home circumstances and level of support.
- Fever.
- Bloody diarrhoea.
- Abdominal pain and tenderness.
- Increased risk of poor outcome, for example coexisting medical conditions, or drugs
- Further management will depend on the cause
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
