MSDEC referral to Gastroenterology

History Taking: Onset, Duration, Frequency, and Severity

A comprehensive history should be obtained, starting with the onset, duration, frequency, and severity of the diarrhoea. 

• Onset of Symptoms: The time of onset can provide important clues about the aetiology. If symptoms appear within 6 hours of consuming contaminated food, it strongly suggests a pre-formed toxin, typically from Bacillus cereus or Staphylococcus aureus. These organisms produce toxins that cause rapid-onset symptoms, typically without the need for active bacterial replication in the gut. Chinese food is sometimes the culprit. 
• Duration and Frequency: More frequent stool passage suggests an infectious cause, particularly if the onset is within days. In contrast, a single episode of diarrhoea may suggest a non-infectious cause, such as dietary indiscretion, or a drug-related issue. The severity of the diarrhoea, such as watery or bloody stools, will guide the diagnostic approach and may indicate whether the cause is likely to be invasive (e.g., Salmonella or Shigella) or toxin mediated. 
• Character of Stools: Watery stools are often associated with non-invasive and toxin-producing pathogens such as Clostridioides difficile (C.Diff) or certain enteric viruses (e.g., norovirus). If the stools are bloody or contain mucus, this raises the possibility of invasive infections or inflammatory bowel disease (IBD), such as ulcerative colitis or Crohn's disease. 

Red Flag Symptoms to identify serious conditions 

A focused enquiry into red flag symptoms is crucial for identifying potentially serious causes of acute diarrhoea. 

• Blood in the Stool: The presence of blood is most often seen with invasive pathogens (e.g., Shigella, Salmonella, Campylobacter) or conditions causing severe inflammation (e.g., ulcerative colitis, ischemic colitis). The nature of the blood (frank vs. occult) and associated symptoms (fever, abdominal pain) will provide further insights. 
• Recent Hospital or Antibiotic Treatment: Recent hospitalisation or antibiotic use raises the possibility of C.Diff infection (often associated with antibiotic use, particularly  clindamycin, cephalosporins, and fluoroquinolones).  
• Weight Loss: This could be indicative of an underlying malabsorption disorder or chronic infectious or inflammatory gastrointestinal pathology. Malignancy should also be considered.
• Signs of Dehydration: Dehydration can rapidly complicate acute diarrhoea, particularly in vulnerable populations (e.g., elderly, immunocompromised). Clinical features of dehydration (e.g., dry mucous membranes, reduced skin turgor, decreased urine output, hypotension) should be carefully assessed. 
• Nocturnal Symptoms: The presence of symptoms that worsen at night (or waking from sleep with abdominal discomfort or diarrhoea) suggests an organic cause, often indicating inflammatory bowel disease (IBD) or cancer rather than a simple viral gastroenteritis. 
• Sexual History: It is essential to enquire about sexual practices, particularly in men who have sex with men, as they are at increased risk for sexually transmitted enteric infections, such as enteric HIV or Giardia 

Assessing for the Underlying Cause of Diarrhoea

A thorough assessment should be made to identify the underlying cause of acute diarrhoea. Specific features suggestive of particular aetiologies include: 

• Stool Characteristics: Watery stools are commonly associated with toxin-producing organisms, viral infections, microscopic colitis, bile acid malabsorption, IBS, while fatty stools may point to malabsorption syndromes (e.g., pancreatic insufficiency or Giardia). The presence of blood or mucus in the stool points to invasive pathogens or an inflammatory cause like IBD. 
• Fever: Often present in invasive infections (e.g., Salmonella, Shigella, Campylobacter, C.diff, enteric viruses). The combination of fever and abdominal cramps can help differentiate between inflammatory diarrhoea and non-inflammatory diarrhoea. 
• Vomiting: This is a common symptom in viral infections (e.g., norovirus), as well as food poisoning from Staphylococcus aureus and Bacillus cereus. When vomiting predominates over diarrhoea, gastroenteritis is likely. 
• Contact with Infected Individuals: Recent exposure to family members or colleagues with similar symptoms should raise suspicion of a viral or bacterial outbreak. In high-risk groups (e.g., food handlers, healthcare workers, nursing home residents), the risk of norovirus, Cryptosporidium, and Giardia infections is higher. 
• Travel History: Travel abroad, especially to developing countries, increases the risk of infection with enteric pathogens (e.g., E. coli, Amoeba, Giardia, Cryptosporidium). Ask specifically about exposure to untreated water, raw milk, or contaminated food (e.g., meat, shellfish, dairy, eggs). 
• New Medications: Newly initiated antibiotics, laxatives, or medications known to alter gut flora can predispose to infections like C. difficile or cause medication-induced diarrhoea. 
• Stool impaction: In frail elderly bed bound patients can be a cause of overflow diarrhoea. 
• First presentation: Sometimes acute diarrhoea could be the first presentation of chronic diarrhoea e.g IBD, Microscopic colitis, IBS, Endocrine disorders (diabetes, hyperthyroidism), bile acid malabsorption, Coeliac disease, small bowel bacterial overgrowth, Colorectal cancer. A careful history taking would be much helpful. 

Assessing for Dehydration

Patients with acute diarrhoea are at risk for dehydration, which can range from mild to severe. 

• Mild Dehydration: Symptoms include nausea, and light-headedness, with postural hypotension commonly seen. 
• Moderate Dehydration: This is marked by tachycardia, dry mucous membranes, muscle cramps, and decreased skin turgor. 
• Severe Dehydration: More concerning signs include shock, altered mental status, and oliguria. These patients require urgent resuscitation and close monitoring. 

While clinical features of dehydration are often useful, they need to be coupled with other observations of the patient.  

Abdominal and Rectal Examination

• Abdominal Examination: Examine for tenderness, distension, or masses. Palpation may reveal increased bowel sounds (suggesting gastroenteritis) or decreased bowel sounds (suggesting more serious conditions like intestinal obstruction). Tenderness in the right lower quadrant may suggest appendicitis or inflammatory bowel disease. 
• Rectal Examination: Assess for rectal tenderness, the presence of blood, mucus, or signs of malignancy. A PR exam can help identify rectal pathology (e.g., cancer, abscesses). 

Investigations

If a specific cause of acute diarrhoea is suspected, appropriate microbiological investigations should be ordered.  

• Stool Sample: QEHB now has access to the enteric PCR Panel which is sent in blue stool pot (need liquid stools for full panel, formed stools will have some targets supressed). Turn around time is 24 hours from arrival in the lab. if the sample is in the lab before 0800 a result will be received in the early afternoon, the aim of this was to catch all samples from ED/AMU from afternoon/overnight. If sufficient samples arrive 2 runs will be done per day, one starting at 8am with results off by late afternoon and a further run will be set up/extracted overnight with the results released mid-morning.  
• If history of travel: Request OCP (ova, cysts, parasites).  
• Blood Tests: include full blood count, CRP, liver function tests, renal function tests, clotting screen.  

When should you admit and/or refer

Patients who meet specific criteria should be considered for hospital admission or specialist referral: 

• Severe Dehydration or Shock: Require immediate intravenous rehydration and monitoring. Those with vomiting and unable to retain oral fluids.  
• Older Adults and Vulnerable Groups: Those over 60, especially with co-morbidities, are at increased risk for complications. 
• Fever with Bloody Diarrhoea: Consider invasive infections.  
• Patients who are immunocompromised  
• Those with abdominal pain and tenderness should be investigated appropriately with imaging +/- surgical referral 
• Diarrhoea ongoing despite negative stool PCR test should be referred to Gastroenterology 
• Those with known IBD should be discussed with Gastroenterology