Irritable Bowel Syndrome (IBS) Diagnosis and Management for adults under the age of 50

Irritable bowel syndrome (IBS) can be difficult to diagnose, and it is important to reach the correct diagnosis while striking the right balance between too few and too many investigations.

This IBS pathway aims to provide a patient focused and cost effective diagnostic and management pathway for people with irritable bowel syndrome.

The objectives are:

  • Support healthcare professionals to make a positive diagnosis of IBS and to manage patients in primary care, if no red flag indicators are present and investigations are normal. A positive diagnosis will help to reduce unnecessary anxiety in people with symptoms of irritable bowel syndrome and to start effective treatment.
  • Where there is diagnostic uncertainty in diagnosing IBS versus inflammatory bowel disease (IBD), to support healthcare professionals in diagnosis with use of faecal calprotectin, reducing avoidable invasive endoscopic procedures
  • Provide earlier access to specialist dietetic support and improve patient experience

Scope

This guidance refers to:

  • Patients aged 18-49 years who present with lower gastrointestinal symptoms in whom you suspect IBS or IBD

Out of scope

This guidance does not cover:

  • Patients under the age of 18 or 50 and over (for patients 50 years old and over please see local FIT testing guidelines)
  • Patients where colorectal cancer is suspected (see red flags)
  • Patients in whom there is diagnostic certainty of an IBS diagnosis

Assessment

Signs and Symptoms

Consider IBS when the patient presents with:

  • Abdominal pain
  • Bloating
  • Change of bowel habit

This is usually accompanied by at least two of the following:

  • Related to defecation
  • Associated with a change in bowel habit
  • Associated with a change in stool form (appearance)

Common additional symptoms include abdominal bloating and distension.

Other features such as lethargy, nausea, depression/anxiety, fibromyalgia, backache & bladder symptoms are common in people with IBS, and may be used to support the diagnosis.

History and Examination

Based on the history, IBS can be divided into:

  • IBS with diarrhoea (IBS-D) = loose (mushy) or watery stools for greater than 25% of bowel movements and hard or lumpy stool for less than 25% of bowel movements.
  • IBS with constipation (IBS-C) = hard or lumpy stools for for greater than 25% of bowel movements and loose (mushy) or watery stools for less than 25% of bowel movements.
  • Mixed IBS (IBS-M) = hard or lumpy stools for less than 25% of bowel movements and loose (mushy) or watery stools for less than 25% of bowel movements.
  • Unspecified IBS: insufficient abnormality of stool consistency to meet criteria for IBS-C, IBS-D, or IBS-M

The classification of IBS patients into sub-groups is useful for clinical practice, but it is common for IBS patients to switch from one subtype to another over time. More than 75% of IBS patients change to either of the other 2 subtypes at least once over a 1-year period.

Differential Diagnoses

Differential diagnoses may include:

  • Inflammatory Bowel Disease (IBD)
  • Coeliac disease
  • Chronic pancreatitis or pancreatic insufficiency (perform faecal elastase)
  • Bile acid malabsorption (common following cholecystectomy)
  • Malignancy
  • Infection

Red Flags

Please see the suspected cancer NICE guidelines NG12 and the latest local DG30 guidelines for faecal immunochemical testing (FIT)in patients 50 years and over. Patients meeting these criteria should be referred via the lower GI 2ww pathway.

Investigations

In adults 18-49 years old, with symptoms suggestive of IBS please organise:

  • Full Blood Count (FBC)
  • Coeliac serology - please do not repeat if previously performed in last 3 years
  • C-reactive Protein (CRP)
  • If diarrhoea, Stool for culture and sensitivity

A positive diagnosis of IBS always helps management: patients without 'red flags' and with normal tests should be managed in primary care. Please see IBS management flowchart.

Diagnostic uncertainty between IBS and IBD

If the above bloods tests are normal but you still suspect IBD please organise:

  • Stool faecal calprotectin – sampling from the first bowel movement of the day when the patient is most symptomatic is recommended. This may increase the diagnostic yield.
  • Please ensure off NSAID and PPIs for 2 weeks prior to testing

IBS symptoms and signs versus IBD

IBS Symptoms IBD-Ulcerative colitis IBD-Crohns disease
Abdominal pain Blood mixed in stool Abdominal Pain
Bloating Diarrhoea including nocturnal Weight loss
Change in bowel habit - Typically alternating Urgency/incontinence Diarrhoea
Other features:
  • mood
  • backache
  • bladder symptoms,
  • Fibromyalgia, headaches
Family history IBD



Erythema nodosum, uveitis
Family history IBD



Erythema nodosum, uveitis

About the Calprotectin stool test

  • Calprotectin is a protein released into the gastrointestinal tract when it is inflamed, such as in inflammatory bowel disease (IBD; Crohn's disease and ulcerative colitis) it is stable protein, so can be detected in the stool by laboratory assay.
  • Elevated levels of faecal calprotectin are found in IBD.
  • By contrast, in functional disorders of the gastrointestinal tract, such as the irritable bowel syndrome (IBS) faecal calprotectin levels are normal.
  • Clinically, it can be difficult to be able to distinguish IBS from IBD based on symptoms, signs and blood tests. Here, faecal calprotectin can be used as a biomarker to support your assessment.
  • No biomarker test is 100% accurate but this IBS care pathway has been shown to be effective and safe in supporting your clinical decision making. (J. Turvill et al, Frontline Gastroenterology, 2017)
What do the results mean?

Faecal calprotectin less than 100 µg/g - IBS is 98% likely

If all blood tests and faecal calprotectin are less than 100 µg/g – reassure and manage as IBS – unless there remains a significant clinical doubt as to the diagnosis.

Faecal calprotectin 100-250 µg/g -IBD is 12% likely

This result is equivocal and the Calprotectin should be repeated in 2 weeks. If the repeat result remains greater than 100 µg/g, then refer urgently to gastroenterology highlighting suspected IBD.

In an unwell patient with acute abdominal pain or significant bloody diarrhoea and possible IBD, do not let primary care investigations delay appropriate urgent assessment, please contact the on call Consultant Gastroenterologist or use the electronic advice and guidance service, otherwise:

Before repeating please exclude:

  • Non-steroidal anti-inflammatory drugs (NSAID) ingestion within the last 2 weeks
  • GI Infection (repeat stool culture)

Faecal calprotectin more than 250 µg/g IBD is 46% likely

In an unwell patient with acute abdominal pain or significant bloody diarrhoea and possible IBD, do not let primary care investigations delay appropriate urgent assessment, please contact the on-call Consultant Gastroenterologist or use the electronic advice and guidance service, otherwise:

More than 250 µg/g – refer urgently to gastroenterology highlighting suspected IBD. Please ensure a stool sample is sent to rule out infection as a possible cause of the symptoms.

Management

For management guidance please see the 'Symptom management' guidance under the Irritable Bowel Syndrome information in the Formulary section of the website here.

***PLEASE NOTE: The recommendations in the management guidance are currently under review, with possible changes to come***

Referral

IBS is a condition to be primarily managed in the community. In patients with symptoms of IBS and that have not responded to simple lifestyle, dietary and pharmacological therapy as recommended by NICE consider referral to the Specialist IBS Dietetic services.

See:

Referrals should only go on to secondary care gastroenterology with a negative faecal calprotectin (less than 100 µg/g) if there remains a significant doubt of the diagnosis of IBS and in severe refractory cases that have not responded to specialist IBS dietary changes and first- and second-line medical treatment. Note referrals to Gastroenterology that have not been managed as per this guideline will be returned.

Referral instructions

Pathway 1: Specialist Dietician pathway

e-Referrals Service Selection

  • Specialty: Dietetics
  • Clinic Type: Gastroenterology
  • Service: DRSS-Eastern-Dietetic-Devon CCG -15N
Pathway 2: Suspected IBD for luminal Gastroenterology (to be seen within 2 weeks)

In an unwell patient with acute abdominal pain or significant bloody diarrhoea and possible IBD, do not let primary care investigations delay appropriate urgent assessment, please contact the on-call Consultant Gastroenterologist or use the electronic advice and guidance service.

Pathway 3: Gastroenterology refractory IBS pathway

e-Referral Service Selection

  • Specialty: GI & Liver
  • Clinic Type: Lower GI (medical) excl IBD
  • Service: DRSS-Eastern-GI & Liver (Medicine & Surgery)-Devon CCG -15N

Please highlight on the referral form that the referral is in relation to refractory IBS

Referral Forms

Supporting Information

Pathway Group

This guideline has been signed off by the Eastern Locality on behalf of NHS Devon CCG.

Publication date: November 2019

 

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