Functional GI Disorders — Written Clinical Reasoning

SAQ 1 — Irritable bowel syndrome (12 marks)

Prompt: A 30-year-old woman has eight months of recurrent lower abdominal pain, about twice a week, related to defecation, with mostly loose stools and bloating. There are no alarm features. Outline your diagnosis, investigations and stepped management. ^[1]

Model Answer

Diagnosis (3 marks):

• Rome IV IBS is recurrent abdominal pain associated with defecation or a change in bowel habits, with onset at least 6 months before diagnosis and symptoms present during the last 3 months. ^[3]
• IBS-D means more than 25 percent of bowel movements are Bristol type 6 or 7. ^[3]
• Make a positive diagnosis from symptoms, in the absence of alarm symptoms or signs and of abnormalities on simple blood and stool tests. ^[1]

Investigations (3 marks):

• Full blood count, CRP or ESR, coeliac serology and, because she is under 45 with diarrhoea, faecal calprotectin to exclude inflammatory bowel disease. ^[1]
• No breath testing for bacterial overgrowth or carbohydrate intolerance, and no pancreatic testing, in typical IBS. ^[1]

First-line management (3 marks):

• Explain the diagnosis and the gut-brain axis; advise regular exercise and first-line dietary advice. ^[1]
• Soluble fibre such as ispaghula, starting at 3 to 4 g/day; avoid insoluble fibre such as wheat bran. Loperamide may help diarrhoea, titrated carefully. ^[1]

Second-line (3 marks):

• A low-FODMAP diet supervised by a trained dietitian, with reintroduction according to tolerance. ^[1]
• A tricyclic antidepressant as a gut-brain neuromodulator, starting at amitriptyline 10 mg once daily and titrating to a maximum of 30 to 50 mg once daily. ^[1]
• In secondary care, 5-HT3 antagonists, rifaximin or eluxadoline are efficacious second-line drugs for IBS-D. ^[1]
• IBS-specific CBT or gut-directed hypnotherapy if symptoms have not improved after 12 months of drug treatment, or earlier if accessible. ^[1]