BSG Guidelines (2003) for the Investigation of Chronic Diarrhoea

Definition

Chronic diarrhoea may be defined as the abnormal passage of three or more loose or liquid stools per day for more than four weeks and/or a daily stool weight greater than 200 g/day.

Prevalence Talley et al reported a prevalence of “chronic

diarrhoea” of between 7% and 14% in an elderly population

estimates of the prevalence of chronic diarrhoea in a Western population are of the order of 4–5%

Algorithm for investigation of chronic diarrhoea

Causes of chronic diarrhoea

Colonic Colonic neoplasia Ulcerative and Crohn’s

colitis Microscopic colitis

Small bowel Coeliac disease Crohn’s disease

Other small bowel enteropathies (for example, Whipple’s disease,

tropical sprue, amyloid, intestinal lymphangiectasia)

Bile acid malabsorption

Disaccharidase deficiency

Small bowel bacterial overgrowth

Mesenteric ischaemia Radiation enteritis Lymphoma Giardiasis (and other

chronic infection)

Causes of Chronic Diarhoea Pancreatic Chronic pancreatitis Pancreatic carcinoma Cystic fibrosis Endocrine Hyperthyroidism Diabetes Hypoparathyroidism Addison’s disease Hormone secreting

tumours (VIPoma, gastrinoma, carcinoid)

Other Factitious diarrhoea “Surgical” causes (e.g.

small bowel resections, internal fistulae)

Drugs Alcohol Autonomic neuropathy

Initial investigations History and Examination Aim to establish: (a) organic vs functional,

(b) malabsorptive vs colonic/inflammatory forms of diarrhoea

(c) to assess for specific causes of diarrhoea.

Symptoms of Organic Diseaseless than three months’ duration,

Predominantly nocturnal or continuous (as opposed to intermittent) diarrhoea,

significant weight loss.

Functional Disease The absence of symptoms of organic disease,

in conjunction with positive symptoms such as those defined in the Manning or Rome criteria and a normal physical examination, are suggestive of a functional bowel disturbance, but only with a specificity of approximately 52–74%.

Unfortunately, these criteria do not reliably exclude inflammatory bowel disease.

Malabsorption

Colonic/Inflammtory

steatorrhoea liquid loose stools with blood

bulky malodorous pale stools

mucous discharge

Inspection of the stool may be helpful indistinguishing these two

Risk Factors for Organic Disease Family history. Particularly of neoplastic,

inflammatory bowel, or coeliac disease. Previous surgery. Previous Pancreatic disease Systemic disease i.e.

Thyrotoxicosis/parathyroid disease Alcohol Drugs Recent overseas travel or other potential

sources of infectious gastrointestinal pathogens

Recent antibiotic therapy and Clostridium difficile infection

Lactase deficiency

Basic Investigations FBC U and Es liver function tests, including albumin vitamin B12 and folate, calcium, ferritin, ESR and CRP TFTs Coeliac screen- EMA (anti endomysial

antibodies),Anti TTG (anti tissue tranglutaminase)

Stool Tests Inspection of stool Stool collection - 24-48hrsIf less than 200g/day, no further investigations

may be warranted

Stool cultures Protozoan, giardasis and amoebiasis ELISA for giardiasis

Stool osmolality – limited use may help in differentiating secretory and osmotic diarrhoea

Functional Disease Symptoms suggestive of Functional disease

< 45 years

Normal basic investigations

Diagnosis = Irritable bowel syndrome

Factitious Diarrhoea a common cause of reported chronic

diarrhoeal symptoms in Western populations.Due to laxative abuse adding of water or urine to stool specimens

Up to 20% of patients that are seen in tertiary centres.

Often underlying psychiatric hx such as eating disorders

High index of suspicion

Colonic/Terminal Ileal Disease Flexible SigmoidoscopyRecommended in patients under 45

because covers most pathology in this age group

Allows assessment and sampling of sigmoid and descending colon

In a study (n=809) of non HIV Non bloody chronic diarrhoea it was demonstrated that 15% of patients had colonic pathology

99.7% of these diagnoses could have been made from biopsies of the distal colon using a flexible sigmoidoscope,

primary diagnoses being microscopic colitis, Crohn’s disease, melanosis coli, and ulcerative colitis.

Colonic/Terminal Ileal Disease

Colonoscopy Recommended in patients over 45 years old Diarrhoea may be caused by colorectal neoplasia One study showed prevalence of colonic

neoplasms of 27% in those patients undergoing colonoscopy for a change in bowel habit

50% of neoplasms are proximal to splenic flexture Higher diagnostic yield with ileoscopy particularly

in IBD preferred modality to exclude or confirm

microscopic colitis Barium Enemas useful in complementing

colonoscopy but has lower sensitivity in detecting neoplasms

Colonic/Terminal Ileal Disease If colonoscopy and barium enema negative:

Barium follow through – further imaging of terminal ileum and proximal colon in patients with negative findings on colonoscopy and biopsy

Enteroclysis/Technetium scan?Superseded by CT with contrast and video

endoscopy

Malabsorption- Small Bowel Upper GI endoscopy with duodenal biopsies

even in absence of EMA/TTG antibodies

Small bowel imaging (barium follow through or enteroclysis) should be reserved for cases where small bowel malabsorption is suspected and distal duodenal histology is normal (C).

Malabsorption- Small Bowel If enteropathy (e.g. Whipple’s , tropical sprue

amyloid)-

Fat malabsorption – faecal elastase and EMA is superior to 3 day

stool samples for fat measurement.Breath tests 14C-triolein absorption to measure

fat absorption in high faecal fat content

Malabsorption- Pancreatic Severe pancreatic insufficiency with

malabsorption is normally associated with pancreatic duct abnormalities. ERCP offers the greatest sensitivity for the diagnosis of ductal changes- (however since the publication of this guideline in 2003 practice has changed as mentioned below MRCP has replaced ERCP as diagnostic option)

MRCP has the potential to replace ERCP as the imaging modality of choice and has the advantage of avoiding the risks associated with ERCP

Malabsorption- Pancreatic Urine tests such as the Pancreolauryl test and

stool tests such as faecal elastase or chymotrypsin –poor sensitivity in mild/moderate pancreatic dysfunction

Serum levels of pancreatic dysfunction are only affected in severe pancreatic dysfunction

Small bowel bacterial overgrowth Culture of small bowel aspirates is the most

sensitive test for SBBO but methods are poorly standardised and positive results may not reflect clinically significant SBBO (B).

Hydrogen breath tests have poor sensitivity but acceptable specificity, and are of value when a positive result is obtained.

The glucose hydrogen breath test is recommended

Bile Acid Malabsorption Bile acid malabsorption (BAM) may occur

when there isterminal ileal disease or resection. Measurement of serum 7α hydroxy-4-cholesten-3-one is an effective test for this but is seldom performed.

75Se homotaurocholate (75Se-HCAT) testing is more widely available and is a sensitive measure

In the absence of these tests a therapeutic trial of cholestyramine is sometimes employed as a test for the presence of BAM, but the validity of this approach has not been subject to study

Hormone Secreting Tumours Diarrhoea due to hormone secreting tumours

is extremely rare and

testing for the presence of excess vasoactive intestinal peptide, gastrin, or glucagon in plasma is recommended only in the presence of high volume watery diarrhoea when other causes of diarrhoea have been excluded

Summary History and examination extremely important Important to exclude ‘functional’ diarrhoea

with basic investigations and thorough history Coeliac serology tests should be done early in

investigation In patients under the age of 45, flexible

sigmoidoscopy is recommended In patients with one first degree relative with

bowel neoplasm and above age of 45 warrant a colonoscopy

Summary Obvious deficiencies in the investigation of

SBBO, pancreatic insufficiency, BAM Empirical therapy is often employed

Gut. 2003 July; 52(Suppl 5): v1–v15.Guidelines for the investigation of chronic diarrhoea, 2nd edition P Thomas, A Forbes, J Green, P Howdle, R Long, R Playford, M Sheridan, R Stevens, R Valori, J Walters, G Addison, P Hill, and G Brydon