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Neurogastroenterology · London

Functional gut assessment, IBS, SIBO and disorders-of-gut-brain interaction - a modern integrated workup.

A structured integrated workup for irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), functional dyspepsia and other disorders of gut-brain interaction - combining stool testing, breath tests, motility studies and neurogastro consultation.

A consultant neurogastroenterologist reviewing a functional gut assessment in a private London clinic

Key facts

The functional gut assessment, at a glance.

A quick summary of what the workup is, what it covers and how it is diagnosed.

  • Definition

    An integrated workup for IBS, SIBO, functional dyspepsia and disorders of gut-brain interaction.

  • Rome IV criteria

    Diagnosis follows the Rome IV symptom-based framework, not a single test result.

  • Organic disease first

    Excludes red-flag organic disease - coeliac, IBD, colorectal cancer - before a functional label is applied.

  • Multi-modal

    Combines stool markers, hydrogen and methane breath testing, motility studies and imaging where indicated.

  • Microbiome and food

    Includes gut microbiome and food-intolerance testing where clinically appropriate.

  • Neurogastro review

    Findings reviewed by a consultant neurogastroenterologist, with a structured plan you can act on.

Indicative pricing

What a private functional gut assessment costs in London.

Indicative ranges across UK private providers.

In short

£950–£1,800, with a written plan typically within 2–3 weeks.

Component Indicative range
Gastroenterology consultation £250–£450
Faecal calprotectin + FIT £120–£220
Hydrogen / methane breath test (SIBO) £220–£380
Comprehensive stool analysis / microbiome panel £350–£650
Full functional gut assessment (integrated workup) £950–£1,800
Neurogastro follow-up consultation £220–£400

Prices vary by clinic and by which components - breath testing, microbiome panels, motility studies - your workup requires.

The problem

A gut workup is only as good as who structures it.

A scattergun of stool and breath tests, ordered without a framework, rarely produces a plan. Rome IV, red-flag exclusion and a neurogastroenterology-led structure - that is what turns tests into a diagnosis.

  • Bloating, pain, altered bowel habit?

    We structure an integrated workup with Rome IV framing and organic-disease exclusion.

  • A SIBO breath test in isolation?

    We put the result in context - with clinical history, red-flag review and a plan you can act on.

What it shows

What a functional gut assessment can diagnose.

The workup covers the commonest disorders of gut-brain interaction - and, just as importantly, excludes the organic disease that must not be missed.

  • IBS-D / IBS-C / IBS-M subtype

    Rome IV classification of irritable bowel syndrome by predominant stool pattern.

  • SIBO / IMO (methane)

    Small intestinal bacterial or methanogen overgrowth on breath testing.

  • Bile acid diarrhoea

    A commonly missed cause of chronic diarrhoea, confirmed on SeHCAT or trial of sequestrant.

  • Coeliac disease (differential)

    Screened by serology, confirmed on duodenal biopsy - excluded early in every workup.

  • Microscopic colitis (differential)

    Chronic watery diarrhoea with normal colonoscopy - diagnosed on biopsy.

  • Functional dyspepsia

    Postprandial distress or epigastric pain syndromes without structural disease.

  • Chronic constipation subtype

    Slow-transit, evacuatory or normal-transit constipation - the subtype changes treatment.

  • Red flag: alarm features (weight loss, rectal bleeding) - 2-week-wait pathway

    Alarm features trigger the NHS 2-week-wait suspected cancer pathway. Do not wait for a private slot.

Treatment options

The next steps after diagnosis.

  • Low-FODMAP dietary trial

    A structured, dietitian-led elimination and reintroduction protocol - the highest-evidence dietary intervention for IBS.

  • Antispasmodics (mebeverine)

    First-line pharmacological option for abdominal pain and cramping in IBS.

  • Peppermint oil

    Enteric-coated peppermint oil - evidence-supported for global IBS symptoms and pain.

  • Neuromodulators (TCA, SNRI)

    Low-dose tricyclics or SNRIs to modulate the gut-brain axis in refractory symptoms.

  • Rifaximin for SIBO

    A gut-selective antibiotic for confirmed small intestinal bacterial overgrowth.

  • Bile-acid sequestrants for BAD

    Colesevelam or colestyramine for bile acid diarrhoea confirmed on SeHCAT.

  • Gut-directed hypnotherapy

    A NICE-recommended psychological therapy with a strong evidence base in IBS.

  • Structured neurogastro follow-up

    Consultant-led review to titrate treatment, adjust diet and monitor response.

Safety, red flags and caveats

What has to be excluded before a functional label.

A functional gut assessment is safe and non-invasive - but the practical points are the red flags that trigger urgent NHS pathways, and the caveats around breath testing, microbiome panels and food-intolerance tests.

Red flags - 2-week-wait pathway

  • · Rectal bleeding
  • · Iron deficiency anaemia
  • · Weight loss
  • · Family history of colorectal cancer
  • · Nocturnal symptoms
  • · Persistent vomiting
  • · Progressive dysphagia
  • · Palpable abdominal mass
  • · Age > 50 with new symptoms

  • Red flags come first

    Rectal bleeding, weight loss, iron deficiency, family history of colorectal cancer - these are excluded before any functional label is applied.

  • Rome IV is symptom-based

    Functional gut disorders are diagnosed on symptom criteria, not one blood test - the framework matters.

  • Breath tests have caveats

    SIBO breath testing has false positives and negatives - results are interpreted in clinical context, not in isolation.

  • Low-FODMAP is short-term

    The elimination phase is 4–6 weeks only - long-term restriction risks nutritional deficiency and microbiome harm.

  • Microbiome tests, with caveats

    Commercial microbiome panels are informative but not yet a clinical diagnostic - we say so up front.

  • Food-intolerance testing caveat

    IgG food-intolerance tests are not evidence-based - we do not recommend them as a first-line investigation.

  • Coeliac test needs gluten

    Coeliac serology and biopsy are only reliable if you are eating gluten - do not cut it out before testing.

  • Colonoscopy where indicated

    A normal blood panel does not exclude IBD or cancer - colonoscopy remains the gold standard where red flags exist.

  • Bring prior investigations

    Previous endoscopy, imaging and stool results materially shorten the workup and sharpen the plan.

Reading your report

A functional gut report can look dense. It isn’t.

Whatever the finding, the report keeps to the same four parts.

A consultant neurogastroenterologist reviewing stool and breath test results on a clinical workstation at a UK private clinic

A quiet reminder

The report is written for your doctor, not for you - and that’s normal.

If you would like us to talk you through it before your follow-up, just ask.

  1. 01 Header

    Presentation and Rome IV screen

    Your symptoms, duration, Bristol stool pattern, red-flag review and Rome IV subtype.

  2. 02 Investigations

    Bloods, stool and breath results

    Coeliac serology, calprotectin, FIT, hydrogen and methane breath curves - with reference ranges.

  3. 03 Findings

    Differential and diagnosis

    The working diagnosis - IBS subtype, SIBO/IMO, functional dyspepsia - and what has been excluded.

  4. 04 Plan

    Structured neurogastro management plan

    Dietary, pharmacological and psychological interventions in a stepped plan you can act on.

Recognised by major UK insurers

BupaAXA HealthVitalityAvivaWPACignaHealixBupaAXA HealthVitalityAvivaWPACignaHealixBupaAXA HealthVitalityAvivaWPACignaHealix

Frequently asked

Everything we get asked about functional gut assessment.

Quick answers on Rome IV, SIBO, colonoscopy, cost and the evidence around food-intolerance testing.

  • What is a functional gut assessment?

    A structured, integrated workup for irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), functional dyspepsia and other disorders of gut-brain interaction - combining stool testing, breath tests, motility studies and neurogastroenterology consultation.

  • What is a disorder of gut-brain interaction?

    It is the modern name - from the Rome Foundation - for what used to be called functional gastrointestinal disorders. It reflects that these conditions arise from disturbed communication between the gut and the brain, not from structural disease. IBS, functional dyspepsia and chronic idiopathic constipation are the commonest examples.

  • What is SIBO and how is it tested?

    Small intestinal bacterial overgrowth is an excess of bacteria in the small bowel that causes bloating, wind, pain and altered stool. It is tested with a hydrogen and methane breath test after a lactulose or glucose challenge. Methane-dominant results indicate intestinal methanogen overgrowth (IMO), which is treated differently.

  • Do I need a colonoscopy?

    Only if red-flag or alarm features are present - rectal bleeding, weight loss, iron deficiency anaemia, new symptoms over age 50, family history of colorectal cancer, or a raised faecal calprotectin. Rome IV allows a positive diagnosis of IBS without colonoscopy when there are no alarm features.

  • How much does a private functional gut assessment cost in London?

    A gastroenterology consultation is £250–£450; a SIBO breath test is £220–£380; a full integrated workup is typically £950–£1,800.

  • Are food-intolerance tests worth doing?

    The commonly marketed IgG food-intolerance tests are not evidence-based and we do not recommend them as a first-line investigation. A structured, dietitian-led low-FODMAP elimination and reintroduction protocol is the highest-evidence dietary approach.

Sources and guidelines

Last reviewed 2026-07-30 · Next review 2027-07-30 · Reviewed by Pulse Atlas Editorial Board,

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In practice, in London

Getting functional gut assessment sorted in London, without the guesswork

With functional gut assessment, the London question is usually about report turnaround and the radiologist reading it - not whether the scan is available. Waiting lists on the NHS for functional gut assessment vary widely by borough and by how the GP letter reads. Privately in London, we can normally offer a slot inside the same week, sometimes within 48 hours if there’s a cancellation. The difference isn’t clinical quality - the consultants are frequently the same faces you’d see on the NHS - it’s the calendar.

A typical private booking for functional gut assessment in London starts with a consultant conversation - sometimes in person on Harley Street or Marylebone, sometimes on video if that suits better. Any imaging or diagnostics happen at a nearby CQC-registered facility, and reports usually land within 24 to 72 hours. The whole loop, from first call to written report, is often done inside a fortnight. For functional gut assessment specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.

Fit matters more than people expect. For functional gut assessment, the right consultant depends on what you actually need - a second opinion, a definitive diagnosis, a bridge into treatment, or reassurance that nothing’s being missed. If a test isn’t the right next step, we’ll say so before you book anything.