How does bile‑acid diarrhoea present in a patient with IBS‑D‑type symptoms, morning urgency after waking, no nocturnal stools, and a history of cholecystectomy or other risk factors for impaired ileal bile‑acid reabsorption?

Clinical Presentation of Bile Acid Diarrhoea

Bile acid diarrhoea presents with chronic watery diarrhoea that occurs shortly after meals and typically improves with fasting, making the postprandial timing a key diagnostic clue. 1, 2

Characteristic Symptom Pattern

The hallmark feature is meal-triggered diarrhoea that reflects the postprandial surge in bile acid delivery to the colon. 2 The mechanism involves unabsorbed bile acids reaching the colon where they stimulate fluid, mucus, and sodium secretion while increasing gastrointestinal motility and stimulating defecation. 1

Typical Daily Pattern

• Morning urgency with repeated defecation is common, where stool consistency changes from an initial formed stool to progressively looser stools as colonic contents are cleared. 3
• Symptoms typically improve or resolve with fasting, distinguishing this from other causes of chronic diarrhoea. 3
• The absence of nocturnal diarrhoea is important—nocturnal symptoms suggest other organic pathology rather than bile acid diarrhoea. 4

High-Risk Patient Profiles

Specific risk factors dramatically increase the likelihood of bile acid diarrhoea and should trigger immediate consideration:

• Terminal ileal resection: Over 80% develop bile acid diarrhoea, with 87-92% showing severe malabsorption. 3, 1
• Cholecystectomy: Up to 10% develop chronic diarrhoea through bile acid malabsorption mechanisms. 3, 1, 2
• Ileal Crohn's disease or radiation enteritis: These conditions impair bile acid reabsorption in the terminal ileum. 2

Overlap with IBS-D

Approximately 30% of patients previously classified as having diarrhoea-predominant IBS actually have bile acid diarrhoea. 2 This represents a critical diagnostic pitfall, as these patients will respond to bile acid sequestrants rather than conventional IBS therapies. 5

The British Society of Gastroenterology emphasizes that patients with IBS-D-type symptoms should be evaluated for bile acid diarrhoea, particularly when risk factors are present. 3

Stool Characteristics

• Watery, loose stools rather than the bulky, malodorous pale stools seen in fat malabsorption. 3, 6
• Liquid consistency without blood or mucous discharge (which would suggest inflammatory or colonic causes). 3
• The severity correlates with the degree of bile acid malabsorption—mild to moderate cases present with watery diarrhoea alone, while severe cases may also have steatorrhea. 6

Important Clinical Distinctions

Symptom presentation alone cannot reliably identify bile acid diarrhoea. 3 The Canadian Association of Gastroenterology explicitly recommends against using symptom presentation as the initial assessment, as no symptoms have consistently predicted a positive diagnostic test. 3

Instead, risk factor assessment (terminal ileal resection, cholecystectomy, or abdominal radiotherapy) should be the initial approach to identify patients requiring further evaluation. 3

Associated Features

• Urgency and fecal incontinence are common and suggest an organic cause such as bile acid malabsorption rather than a functional disorder. 2
• Symptoms may worsen with high-fat meals, which increase bile acid secretion. 4
• Quality of life is significantly impaired, with patients experiencing decreased well-being comparable to other chronic gastrointestinal conditions. 7

Key Diagnostic Pitfall

The most critical error is attributing these symptoms to IBS without considering bile acid diarrhoea, particularly in patients with cholecystectomy or ileal disease. 2, 5 Given that approximately 25-50% of patients with functional diarrhoea or IBS-D have evidence of bile acid diarrhoea, this diagnosis must be actively excluded in appropriate clinical contexts. 5