Chronic Abdominal Pain — Free SCA Practice Case

1. Diagnosing IBS: Rome IV Criteria and Positive Diagnosis

• ●IBS is a positive diagnosis, not a diagnosis of exclusion. Apply the Rome IV criteria: recurrent abdominal pain at least one day per week in the last three months, associated with two or more of — pain related to defecation, change in stool frequency, or change in stool form.
• ●Additional supportive features include: straining or urgency, sensation of incomplete evacuation, mucus in stool, and abdominal bloating or distension that worsens through the day.
• ●A positive diagnosis can be made confidently in primary care once red flags are excluded (see Section 6) and the symptom pattern fits — no further investigation is required to confirm IBS.
• ●The characteristic diurnal bloating pattern (flat abdomen in the morning, progressive distension through the day) is a strongly supportive functional feature; structural causes of bloating do not follow this pattern.

2. The Coeliac Screen: A Critical Validity Nuance

• ●Coeliac disease is confirmed (or excluded) by serum tissue transglutaminase IgA (tTG-IgA) — but this test is only valid if the patient has been consuming gluten-containing foods (at least 10g of gluten per day, roughly equivalent to 4 slices of bread) for a minimum of 6 weeks before testing.
• ●A patient who has already self-excluded gluten before the blood test will have a falsely negative result — a clinically important and commonly missed error.
• ●If the prior test was taken after dietary gluten exclusion, arrange a repeat tTG-IgA after confirmed gluten reintroduction for 6 weeks. Explain to the patient that the first test was not invalid through anyone's fault — gluten reintroduction requirements are not widely known and she should not have been expected to know this.
• ●Always check total serum IgA alongside tTG-IgA to exclude IgA deficiency, which causes false-negative coeliac serology.

3. Investigating to Exclude IBD: Faecal Calprotectin

• ●Faecal calprotectin is the recommended first-line investigation to differentiate IBS from inflammatory bowel disease (IBD: Crohn's disease, ulcerative colitis) in primary care. It is non-invasive, inexpensive, and has a high negative predictive value for IBD.
• ●NICE CKS recommends offering faecal calprotectin to adults with recent-onset lower GI symptoms where IBD is a clinical consideration and colorectal cancer is not suspected.
• ●Interpretation: A result below 50 µg/g makes IBD very unlikely (IBS diagnosis supported). A result above 200 µg/g warrants urgent secondary care referral. Results in the 50–200 µg/g grey zone should be repeated in 4–6 weeks; persistent elevation warrants further investigation.
• ●A normal calprotectin result is a powerful tool for reassuring a patient who fears Crohn's disease — frame it as a definitive objective test, not just another normal result.

4. Dietary Management: FODMAPs and Fibre

• ●FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) are short-chain carbohydrates that are poorly absorbed in the small bowel and rapidly fermented by colonic bacteria, producing gas, bloating, and altered bowel habit. Common high-FODMAP foods include apples, stone fruits (peaches, plums, cherries), lentils, onions, garlic, and wheat.
• ●A low-FODMAP diet is an evidence-based approach for IBS symptom management. It should be offered as a structured, time-limited intervention — typically 4–8 weeks of restriction followed by systematic reintroduction to identify individual trigger foods. It is not intended as a permanent exclusion diet.
• ●Refer to a dietitian for supervised low-FODMAP guidance wherever possible. Unsupervised long-term FODMAP restriction risks nutritional inadequacy and is harder to sustain; a dietitian ensures correct implementation and safe reintroduction.
• ●When explaining FODMAPs to a patient who eats "healthily," reframe sensitively: certain foods that are nutritious for most people happen to be poorly tolerated by an overactive gut — this is not a criticism of their dietary choices.
• ●Fibre advice must be specific: recommend soluble fibre (ispaghula husk/Fybogel, oats) for constipation-predominant symptoms. Avoid insoluble fibre (wheat bran, bran cereals) — it accelerates gut transit but worsens bloating and abdominal pain in IBS.
• ●General IBS lifestyle advice (NICE CKS): eat regular meals without skipping, avoid large meals, limit caffeine, alcohol, and fizzy drinks, and encourage regular physical activity.

5. Pharmacotherapy: First- and Second-Line Options

• ●First-line for pain and bloating: Prescription antispasmodics — mebeverine 135mg three times daily (taken 20 minutes before meals) or alverine citrate 60–120mg up to three times daily. Peppermint oil capsules (enteric-coated) are an alternative. Over-the-counter hyoscine butylbromide (Buscopan) has a weaker evidence base; if it has already failed, step up to a prescription antispasmodic rather than repeating it.
• ●For diarrhoea-predominant episodes: Loperamide taken as needed (PRN) — not regularly — at the lowest effective dose. Advise the patient to use it reactively for urgency episodes rather than as a daily preventive.
• ●For constipation-predominant episodes: Macrogol (polyethylene glycol) is preferred. Avoid lactulose — it is itself a FODMAP (a disaccharide) and will worsen bloating and flatulence in IBS.
• ●Second-line for refractory pain: Low-dose amitriptyline (starting at 5–10mg nocte) acts as a gut-pain modulator via its effect on visceral afferent nerves — this is entirely distinct from its antidepressant use at higher doses (typically 75–150mg). Explain this clearly and proactively: "I'm recommending this at a very low dose specifically to calm the nerve signals from your gut — it's a completely different use from treating depression." Do not introduce it without this explanation; a patient already on sertraline will be understandably resistant.
• ●Amitriptyline and sertraline: Combination use is generally safe at these doses but is worth acknowledging. The main interaction concern (serotonin syndrome) is primarily relevant at higher doses; at 5–10mg nocte, the risk is low. There is no absolute contraindication, but document the rationale.

6. Red Flags and Safety Netting

• ●Red flags requiring urgent review or same-day action: unintentional weight loss, rectal bleeding, symptoms that wake the patient from sleep (nocturnal pain or diarrhoea is almost never functional), new palpable abdominal or rectal mass, iron deficiency anaemia, age over 60 with new change in bowel habit.
• ●Nocturnal symptoms are a critical differentiator: IBS symptoms do not wake patients at night. If a patient reports being woken by pain or diarrhoea, this points strongly to organic disease (IBD, microscopic colitis) and warrants urgent investigation.
• ●Safety-netting instruction: advise the patient to return promptly if she develops any of the above, and to re-attend if her symptoms significantly worsen despite treatment. Do not rely on vague instructions to "come back if it gets worse" — name the specific features.
• ●Follow-up: arrange a structured review at 6–8 weeks to check faecal calprotectin and repeat coeliac results, assess response to dietary and pharmacological management, and agree next steps. Proactive follow-up reinforces that the diagnosis is being taken seriously and maintains the therapeutic relationship.

7. The Gut-Brain Axis: Explaining IBS Mechanisms

• ●IBS is classified as a disorder of gut-brain interaction (DGBI) — formerly called functional bowel disorder. The enteric nervous system (the gut's own intrinsic nervous system) becomes sensitised, so normal amounts of gas or luminal content trigger disproportionate pain signals. This is visceral hypersensitivity.
• ●A useful patient-friendly explanation: "Your gut has its own nervous system, and in IBS the volume is turned up too high — signals that wouldn't bother most people cause significant pain in you. This is a real neurological process in your gut, not something you're imagining."
• ●This framing is clinically important: it explains the mechanism without attributing symptoms to anxiety or psychological causes, validates the physical reality of symptoms, and provides a rationale for treatments targeting nerve sensitisation (such as low-dose amitriptyline or gut-directed psychological therapies).
• ●Avoid the phrase "functional" without explanation — patients often interpret it as "there's nothing wrong with you." Prefer "disorder of gut-brain interaction" or "your gut nerves are overactive."

8. Multimorbidity Awareness: IBS, Anxiety, Dysmenorrhoea, and NSAIDs

• ●IBS, generalised anxiety disorder (GAD), and dysmenorrhoea share pathophysiological mechanisms — central sensitisation and altered pain processing — which explains their frequent co-occurrence. Recognising this is important, but these shared mechanisms must never be used to dismiss GI symptoms as "just anxiety."
• ●Menstrual cycle and IBS are closely linked: oestrogen and progesterone influence gut motility, and IBS symptoms frequently worsen perimenstrually. This is not coincidence — it is a recognised physiological relationship. For Emily, the worsening of cramps and bloating around her period is consistent with both her IBS and her dysmenorrhoea.
• ●NSAIDs and the GI tract: Mefenamic acid (an NSAID) can cause or worsen GI symptoms including abdominal pain, diarrhoea, and nausea. In a patient with IBS, consider whether NSAID use during menstruation is contributing to symptom flares. This does not necessarily mean stopping mefenamic acid — its benefit for dysmenorrhoea is established — but it warrants acknowledgement and monitoring.
• ●If IBS symptoms remain refractory after first- and second-line measures, consider gut-directed psychological therapies (gut-directed CBT, gut-directed hypnotherapy) — these have a robust evidence base for IBS and are recommended by NICE CKS as third-line options.