Practical Diagnostic Approach to Chronic Diarrhoea

Mashiko Setshedi 01 Feb 2019

Overview

Gastroenterology.1999;116(6):1464-1486.AmJEpidemiol1992;136:165–77.

Several hundred possible differential diagnoses

Chronic diarrhoea is common (3-5% of population)

Considerable diagnostic challenge

AmFamPhysician2011;84(10):1119-1126

What is chronic diarrhoea?

? Stool form, frequency, consistency Objective >200g of stool per day (unreliable) Accepted definition > 3 BMs per day Bristol ≥ 5 Chronic > 4 weeks

N.B: Exclude pseudo-diarrhoea (increased frequency, but normal consistency

Sub-types of diarrhoea

OLD

Osmotic Secretory

Inflammatory

Fatty

Dysmotility

NEW

Watery (osmotic, secretory, dysmotility)

Subtypes

Fatty

Inflammatory

AmFamPhysician2011;84(10):1119-1126

AmFamPhysician2011;84(10):1119-1126

AmFamPhysician2011;84(10):1119-1126

AmFamPhysician2011;84(10):1119-1126

PrimarySclerosingCholangi2s(PSC)DescribediarrhoeaOnset?PaCern

-conFnuous-intermiCent-nocturnalsymptoms

Associatedfeatures(pain,fever,gasetc)Alarmfeatures(new-onsetdiarrhoea,persistentbloodinstool,unintenFonalLOW)

Approach - history

PrimarySclerosingCholangi2s(PSC)DescribediarrhoeaOnset?PaCern

-conFnuous-intermiCent-nocturnalsymptoms

Associatedfeatures(pain,fever,gasetc)Alarmfeatures(new-onsetdiarrhoea,persistentbloodinstool,unintenFonalLOW)

Approach - history

PrimarySclerosingCholangi2s(PSC)DescribediarrhoeaOnset?PaCern

-conFnuous-intermiCent-nocturnalsymptoms

Associatedfeatures(pain,fever,gasetc)Alarmfeatures(new-onsetdiarrhoea,persistentbloodinstool,unintenFonalLOW)Associa2ons

-travel,food(dairy,sweeteners,FODMAPS,gluten,alcohol,caffeine,liquorice)

Approach - history

PastmedicalhistoryFamilyhx(IBD,coeliacdisease)OthermedicalcondiFons-thyroid,DM,collagenvasculardisease,pancreaFcdiseasePrevioussurgery(e.g.SBresecFon,cholecystectomy)PreviousradiotherapyMedica2ons(over700implicated)

AmFamPhysician2011;84(10):1119-1126

VitalsignsGeneralappearance–anorexia/bulimiaOedema,lymphnodesThyroidmassSkinrashes(DH),flushingAbdomen–scars,tenderness,masses,organomegalyRectalexam-sphinctertoneandsqueeze,fistulae

Approach – physical examination

Diagnostic objective

Make a positive diagnosis with minimal investigations

Detect common but underdiagnosed disorders such as bile acid diarrhoea, microscopic colitis, lactose malabsorption or post-radiation diarrhoea

Exclude cancer or inflammation

Initial approach

17

Hb,Feifanaemic,CRP,albumin,TSH,coeliacserologyANDStoolMCS,ova,cysts,parasites,faecalcalprotecFn(>50g/g),considerFIT

IfnegaFve,and<40,andnoalarmfeaturesandmeetsRomeIV

ConfirmIBS.Ifneedsbe,flexiblesigmoidoscopy

IftroublesomesymptomsdespitetreatmentforIBS

ConsiderCoeliacdisease(g-scope+duodenalbiopsies)MicroscopiccoliFs(colonoscopy+biopsies)Bilesaltdiarrhoea(empiricbileacidsequestrants)

Who should be investigated further?

Abnormal initial tests Normal first-line investigations with severe symptoms severe enough to impair QOL No response to initial treatment/ongoing symptoms Suspected organic disease

Watery Inflammatory Fatty Other

Osm>125mmol/kgOSMOTIC

HistoryosmoFclaxaFvesWorsewithdairyproducts–hydrogenbreathtestConsidercoeliacdisease

ApplyRomeIVIBSorfuncFonaldiarrhoeaExcludecoeliacdisease

Osm<50mmol/kgSECRETORY

NormalOsmDYSMOTILITY

StoolanalysisColonoscopy(microscopiccoliFs≥8biopsies)MRI/CTTSH/ACTHTestsforhormone-secreFngtumoursLaxaFvescreen

Watery

Osm>400mmol/kgCONTAMINATION/SPURIOUS

StoolanalysisposiFveforRBCs,WBCs

Colonoscopy+biopsies±FCP

ConfirmIBDorinfecFouse.g.pseudomembranous,amoebic,CMVcoliFs

Treatappropriately Inves2gateothercauses

Inflammatory

YES NO

Hb,Alb,Fe,VitB12,folate

Malabsorp2on

Gastroscopy+duodenalbiopsiesMREVCEDBESBBO–trialanFbioFcs

Maldiges2on

FaecalelastaseMRIpancreas(CTifMRIunavailable)

Fatty

If all else fails, think constipation!

N.B:withoverflowdiarrhoeaExcludefaecalinconFnence

-KUB-analmanometry-endoanalUS

7-step approach

3.Isitcolonic,smallbowelorpancreaFcdisease?

1.Isitdiarrhoea?Establishthatitis.

2.IsitfuncFonalororganic?

4.Isitinflammatory,watery,faCy?5.Determinespecificcause.

6.CoulditbeconsFpaFon/pelvicpathology?

7.CoulditbefacFFous(4-20%)?

Learning Points

Testearlyforcoeliacdisease

Minimal/non-invasivestep-wiseinvesFgaFonstoarriveatadiagnosis

MostchronicdiarrhoeaisduetocolonicabnormaliFesandgenerallynotinfecFous

SomecondiFonsaremorecommonthanwethink

Itbeginswithafocused,comprehensivehistory