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MELD-NaAssesses the severity of chronic liver diseaseChild-Pugh ScoreAssesses the prognosis of chronic liver disease, mainly cirrhosisFIB-4 IndexLiver fibrosis scoring indexAPRIAST to platelet ratio — liver fibrosisMaddrey's DFAlcoholic hepatitis severityGlasgow-BlatchfordUpper GI bleed risk stratificationGAHSGlasgow alcoholic hepatitis scoreMontreal IBDIBD classification — CD & UCMayo ScoreUlcerative colitis activityBISAP ScoreBedside index for severity of pancreatitisCLIF-SOFAOrgan failure scoring in cirrhosisAlcohol ContentStandard drinks & alcohol grams calculatorAARC-ACLFAcute-on-chronic liver failure gradePELD / CR ScorePediatric end-stage liver diseaseHarvey-BradshawCrohn's disease activity indexCTSICT severity index — pancreatitisRockall ScoreGI bleed rebleeding & mortality riskCAGEAlcohol use disorder screening (4 questions)MELD 3.0Updated MELD — sex-inclusive formulaAUDIT ScoreAlcohol use disorders identification testVOCAL-Penn ScorePost-operative mortality risk in cirrhosis surgery

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17
ALBI GradeAlbumin-bilirubin liver function grade in HCCUKELD ScoreUK model for end-stage liver diseaseMELD-XIMELD excluding INR — for anticoagulated patientsWest Haven CriteriaHepatic encephalopathy gradingMilan CriteriaLiver transplant eligibility in hepatocellular carcinomaLI-RADS v2018 (CT/MRI)Liver observation category from size, APHE and major featuresBCLC StagingHepatocellular carcinoma stage and treatment allocationSimplified AIH CriteriaSimplified criteria for autoimmune hepatitisRevised Original AIH ScoreIAIHG 1999 comprehensive autoimmune hepatitis scoreSAAGSerum-ascites albumin gradient — cause of ascitesR FactorHepatocellular vs cholestatic pattern in liver injuryCLIF-C ACLFMortality prediction in acute-on-chronic liver failureKing's College CriteriaTransplant criteria in acute liver failureGALAD ScoreHCC detection from gender, age, AFP-L3, AFP and DCPMetroticket 2.0AFP-adjusted up-to-seven for HCC transplant eligibilityRUCAMCausality in drug- and herb-induced liver injuryBaveno VII CriteriacACLD, CSPH and sparing screening endoscopy

Fibrosis & MASLD

8
NAFLD Fibrosis ScoreAdvanced fibrosis probability in MASLD/NAFLDBARD ScoreBMI, AST/ALT ratio, diabetes — MASLD fibrosisFatty Liver IndexPredicts hepatic steatosis from routine labsFibrotic NASH Index (FNI)At-risk NASH probability from AST, HbA1c and HDLNAFLD Activity Score (NAS)Histologic activity grade — steatosis, inflammation, ballooningMEFIB IndexMRE + FIB-4 rule for significant fibrosis (≥F2) in MASLDFAST ScoreFibroScan-AST — at-risk NASH from LSM, CAP and ASTSAFE ScoreSteatosis-Associated Fibrosis Estimator for MASLD in primary care

Pancreas & Biliary

8
Ranson's CriteriaAcute pancreatitis severity at 48 hoursGlasgow-Imrie CriteriaAcute pancreatitis severity — the PANCREAS criteriaHAPSHarmless acute pancreatitis scoreTokyo Guidelines — CholangitisTG18 diagnosis and severity grade for acute cholangitisTokyo Guidelines — CholecystitisTG18 diagnosis and severity grade for acute cholecystitisBiliary Pain (Rome IV)Rome IV — defining biliary-type pain before interventionFunctional Pancreatic SODRome IV — pancreatic sphincter of Oddi disorderRevised Atlanta ClassificationAcute pancreatitis severity — mild, moderately severe, severe

IBD

9
Truelove & Witts CriteriaAcute severe ulcerative colitis — admission decisionUCEISUlcerative colitis endoscopic index of severitySCCAISimple clinical colitis activity index — symptoms onlyCDAICrohn's disease activity index — the trial standardSES-CDEndoscopic severity in Crohn's diseasePUCAIPaediatric ulcerative colitis activity indexTravis (Oxford) CriteriaDay 3 colectomy risk in acute severe ulcerative colitisHo IndexDay 3 steroid failure risk in acute severe ulcerative colitisRutgeerts ScorePostoperative Crohn's recurrence at ileocolonoscopy

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EVendo ScorePredicts oesophageal varices needing treatmentForrest ClassificationPeptic ulcer bleeding — rebleeding risk at endoscopyAIMS65 ScoreUpper GI bleed mortality — five bedside criteriaOakland ScoreSafe-discharge risk for acute lower GI bleedingABC ScoreAge, blood tests, comorbidities — GI bleed mortalitySarin ClassificationEndoscopic classification of gastric varicesEGUS (Gastric Ulcer)Malignancy risk in a gastric ulcer, and who needs repeat endoscopy

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2
ABIC ScoreAge, bilirubin, INR, creatinine — alcoholic hepatitisLille ModelSteroid response at day 7 in alcoholic hepatitis

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4
Chicago Classification v4.0Oesophageal motility pattern from high-resolution manometryLA Classification (Oesophagitis)Los Angeles grade A–D for erosive oesophagitisPrague C & M CriteriaCircumferential and maximal extent of Barrett's oesophagusEREFS (Eosinophilic Oesophagitis)Endoscopic reference score — oedema, rings, exudates, furrows, stricture

Colorectal

3
Boston Bowel Prep ScaleColonoscopy preparation adequacy by segmentStool Osmotic GapOsmotic vs secretory diarrhoea from stool electrolytesATLAS Score (C. difficile)Predicted response to therapy in Clostridioides difficile infection

Functional GI

37
Bristol Stool ScaleStool form types 1–7 and colonic transitRome IV Criteria for IBSIrritable bowel syndrome diagnosis and subtypeFunctional ConstipationRome IV — two of six items, IBS excludedOpioid-Induced ConstipationRome IV — constipation tied to opioid therapyFunctional DiarrhoeaRome IV — loose stools without predominant painFunctional Bloating / DistensionRome IV — bloating without other bowel disorder criteriaUnspecified Functional Bowel DisorderRome IV — bowel symptoms fitting no other categoryCentrally Mediated Abdominal Pain (CAPS)Rome IV — continuous pain unrelated to gut eventsNarcotic Bowel SyndromeRome IV — opioid-induced hyperalgesia of the gutFaecal Incontinence (Rome IV)Rome IV — the criteria, and why nobody is askedFunctional Anorectal PainLevator ani, unspecified pain and proctalgia fugaxFunctional Defecation DisordersRome IV — dyssynergia and inadequate propulsionInfant RegurgitationRome IV — the happy spitter, and the alarm features that rule it outInfant ColicRome IV — recurrent unexplained crying in a well infant under 5 monthsInfant DyscheziaRome IV — straining before a soft stool, and why not to intervenePaediatric Functional ConstipationRome IV — two of six over one month, with overflow soiling as a criterionToddler's DiarrhoeaRome IV functional diarrhoea of childhood — painless, thriving childPaediatric Cyclic Vomiting SyndromeRome IV — both age bands, with different criteria for eachPaediatric Rumination SyndromeRome IV — infant and child/adolescent criteriaFunctional Nausea & Vomiting (Children)Rome IV — two separate disorders that can be met togetherAerophagiaRome IV — distension that increases through the dayPaediatric Functional DyspepsiaRome IV — four times a month, with PDS and EPS subtypingPaediatric Irritable Bowel SyndromeRome IV — plus the constipation clause clinicians missAbdominal MigraineRome IV — stereotypical incapacitating episodes weeks apartFunctional Abdominal Pain — NOSRome IV — the residual category, reached after the other threeNonretentive Faecal IncontinenceRome IV — soiling without retention, where laxatives make it worseFunctional DyspepsiaRome IV — with PDS and EPS subtypingRumination SyndromeRome IV — effortless regurgitation without retchingCyclic Vomiting SyndromeRome IV — stereotypical episodic vomitingCannabinoid HyperemesisRome IV — CVS pattern relieved by cannabis cessationChronic Nausea & VomitingRome IV — chronic nausea and vomiting syndromeBelching DisordersRome IV — supragastric vs gastric belchingFunctional HeartburnRome IV — heartburn with normal acid exposureReflux HypersensitivityRome IV — normal acid exposure, positive symptom associationFunctional Chest PainRome IV — non-cardiac, non-reflux chest painGlobusRome IV — painless lump-in-throat sensationFunctional DysphagiaRome IV — dysphagia with normal endoscopy and manometry
  1. Calculators
  2. /
  3. Centrally Mediated Abdominal Pain (CAPS)
Functional GI

Centrally Mediated Abdominal Pain (CAPS)

Rome IV — continuous pain unrelated to gut events

The defining feature. Pain that tracks meals or bowel movements points to a gut-driven disorder; pain that does not is centrally mediated. Some degree of gastrointestinal dysfunction may still be present.

Work, intimacy, social and leisure activity, family life, or caring for self or others.

Continuous or nearly continuous abdominal pain with little or no relationship to eating, defecation or menses — that dissociation from gut events is what makes it centrally mediated.

When to use
Use it in a patient with chronic, largely constant abdominal pain whose symptoms have not tracked meals or bowel movements and whose organ-based work-up is complete and negative. It is the diagnosis for a group who are otherwise poorly served — repeatedly investigated, repeatedly told nothing is wrong, and frequently escalated onto opioids that make the problem worse. It does not apply where pain fluctuates with eating or defecation, which points to a gut-driven functional disorder, and it should not be reached for while the organ-based assessment is still open.
Why use it
Because the default trajectory for this patient is harmful. Continuous abdominal pain without an explanation attracts repeated imaging, repeated endoscopy, occasionally laparoscopy, and — most damagingly — escalating opioids, which in this population produce narcotic bowel syndrome and worsen the pain they were prescribed for. Naming the disorder changes the model from 'find the lesion' to 'treat the pain processing', and that redirects treatment to central neuromodulators and psychological therapies, which have evidence. It also changes the therapeutic goal, from abolishing pain to restoring function, and setting that expectation explicitly is one of the more effective things a clinician can do here.
Formula, evidence and interpretation

About the Rome IV Criteria for Centrally Mediated Abdominal Pain Syndrome

Pain that ignores the gut is the defining feature. Rome IV requires continuous or nearly continuous abdominal pain with no — or only occasional — relationship to physiological events such as eating, defecation or menses; pain that limits some aspect of daily functioning; pain that is not feigned; and pain not explained by another structural or functional gastrointestinal disorder or other medical condition. Criteria are fulfilled over three months with onset at least six months ago. That dissociation from gut events is what makes it centrally mediated: the pain is generated and amplified in the central nervous system rather than driven by anything happening in the bowel.

On this page

  • Formula
  • Interpreting the result
  • Inputs
  • What it returns
  • How it is calculated
  • Facts & figures
  • Evidence
  • How it compares
  • Pearls & pitfalls
  • Critical actions
  • Why it exists
  • About the creator
  • Limitations
  • If you are the patient
  • FAQ
  • Related calculators
  • References

Formula

CAPS = timing AND continuous pain AND no/occasional relationship to physiological events AND limits daily functioning AND not feigned AND not explained by another condition
No or only occasional relationship
The pivotal criterion. Occasional association is permitted; a consistent relationship to meals or defecation is not, and points to a gut-driven disorder.
Limits daily functioning
Work, intimacy, social and leisure activity, family life, or caregiving. Impairment is part of the definition rather than a consequence of it.
  • Rome IV notes that CAPS is typically associated with psychosocial comorbidity, but that there is no specific profile that can be used to make the diagnosis — its absence does not exclude CAPS and its presence does not establish it.
  • Some degree of gastrointestinal dysfunction may be present without invalidating the diagnosis.
  • 'The pain is not feigned' is stated as a criterion, which is unusual and reflects how often these patients are disbelieved.
  • The exclusion covers other functional gastrointestinal disorders as well as structural disease — CAPS is not a label for pain that happens alongside IBS.

Interpreting the result

Meeting the criteria should change three things at once. The explanation comes first: describe central sensitisation in concrete terms — the volume control on pain signalling is turned up, the pain is real, and the absence of findings on scans is expected rather than reassuring-but-puzzling. Second, set the goal as improved function rather than abolition of pain, and say so at the outset; a patient who expects to be made pain-free will judge effective treatment a failure. Third, start a central neuromodulator — tricyclics, SNRIs, or a combination — at doses chosen for pain rather than mood, and introduce psychological therapy alongside rather than after drug failure, since offering it only once medication has failed reads to patients as a statement that the pain was psychological all along. Establish one clinician as the point of contact and schedule regular reviews rather than symptom-triggered visits, which reinforce the pain cycle. Avoid opioids entirely: in this population they produce narcotic bowel syndrome, which has its own Rome IV criteria and requires withdrawal to treat.

ScoreBandWhat it meansAction
All criteria metCentrally mediated abdominal pain syndromeContinuous abdominal pain dissociated from gut events, limiting daily functioning, with organ-based causes excludedCentral neuromodulators plus psychological therapy; function-focused goals; avoid opioids entirely
Pain tracks eating, defecation or mensesCriteria not met — organ-driven patternA consistent relationship to physiological events points to a gut-driven functional disorderAssess for IBS, functional dyspepsia or another organ-based functional disorder
On escalating opioids with worsening painCriteria not met — consider narcotic bowel syndromePain that worsens as opioid doses rise is a different disorder requiring withdrawalAssess for narcotic bowel syndrome

What the Centrally Mediated Abdominal Pain (CAPS) needs (6 inputs)

Timing
Criteria fulfilled for the last three months with symptom onset at least six months before diagnosis.
Continuous or nearly continuous abdominal pain
Not episodic. Pain that comes and goes in discrete attacks points elsewhere; CAPS is characterised by pain that is essentially always present.
No or only occasional relationship of pain with physiological events such as eating, defecation or menses
The defining criterion. Rome IV permits some degree of gastrointestinal dysfunction to coexist — what it does not permit is the pain reliably tracking gut events, which would indicate an organ-driven disorder.
Pain limits some aspect of daily functioning
Rome IV lists work, intimacy, social and leisure activity, family life, and caring for oneself or others. This criterion is why the disorder is defined partly by disability rather than by intensity alone.
The pain is not feigned
An unusual criterion to state explicitly, and included because these patients are so often disbelieved. It is a statement that the pain is real, not an invitation to assess credibility.
Pain is not explained by another structural or functional gastrointestinal disorder or other medical condition
The exclusion that requires the organ-based work-up to be complete. Note it excludes other *functional* disorders as well as structural disease.

What it returns

Criteria met or not met
All five criteria plus the timing rule must hold simultaneously.
Which criteria remain outstanding
Named explicitly. A failure on the physiological-relationship criterion usually means an organ-based functional disorder is the better fit.

How it is calculated

The model underlying CAPS is central sensitisation rather than peripheral pathology. In the normal state, the central nervous system filters and damps visceral afferent signalling; in CAPS that filtering fails and descending inhibition is impaired, so ordinary or absent peripheral input is experienced as continuous pain. That accounts for the criteria directly: the pain is continuous because it does not depend on an intermittent peripheral trigger, and it is dissociated from eating and defecation because those events are not driving it. The model also explains why the disorder responds to central neuromodulators and psychological therapies and not to gut-directed agents, and why opioids are actively harmful — they promote hyperalgesia in a system already failing to inhibit. Rome IV's inclusion of functional impairment in the definition follows from the same framing, since central pain syndromes are characterised by their effect on life rather than by a measurable lesion.

Facts & figures

What separates CAPS from the organ-based functional disorders
FeatureCAPSIBS / functional dyspepsia
Pain patternContinuous or nearly continuousEpisodic or fluctuating
Relationship to eating or defecationNone, or only occasionalCentral to the definition
Primary mechanismCentral sensitisationVisceral hypersensitivity plus motility
First-line treatmentCentral neuromodulators and psychological therapyGut-directed agents, diet, then neuromodulators
Functional impairmentPart of the diagnostic criteriaNot a criterion

A patient whose pain reliably worsens after meals or eases after opening their bowels does not have CAPS, however severe and chronic the pain is.

Why opioids are the specific thing to avoid
ConsequenceDetail
Opioid-induced hyperalgesiaAmplifies pain in a system already failing to inhibit it
Narcotic bowel syndromeA distinct Rome IV disorder — pain worsens as doses escalate, with a 'soar and crash' pattern
Opioid-induced constipationAdds a second problem that does not develop tolerance
Reinforcement of the pain cycleSymptom-triggered dosing rewards attention to the pain

CAPS is one of the few pain syndromes where the intuitive escalation is precisely the wrong move, and where recognising that is the main clinical value of the diagnosis.

Evidence

Derivation — Rome Foundation, centrally mediated disorders committee

2016

Consensus criteria from the Rome IV committee on centrally mediated disorders of gastrointestinal pain, published in Gastroenterology in 2016. Rome IV renamed what Rome III called functional abdominal pain syndrome, to reflect the central mechanism explicitly.

Consensus-derived. The renaming was the substantive change, alongside the explicit statement that psychosocial comorbidity is typical but that no specific profile can be used diagnostically.

Companion disorder — narcotic bowel syndrome

2016

Rome IV defines narcotic bowel syndrome in the same chapter, describing opioid-induced gastrointestinal hyperalgesia in patients treated with chronic or high-dose opioids.

Its inclusion alongside CAPS reflects the clinical reality that patients with centrally mediated pain are frequently escalated onto opioids and develop a second, iatrogenic pain disorder as a result.

Neuromodulator evidence base

2016

The Rome IV chapter sets out the evidence for central neuromodulators — tricyclic antidepressants, serotonin-noradrenaline reuptake inhibitors and combination approaches — in centrally mediated gastrointestinal pain.

Supports neuromodulators at pain-modulating rather than antidepressant doses as first-line pharmacological treatment, combined with psychological therapies.

How it compares

Centrally Mediated Abdominal Pain (CAPS) vs Narcotic bowel syndrome

The iatrogenic sequel — CAPS patients escalated onto opioids frequently develop it, and the treatment reverses from adding analgesia to withdrawing it.

Rome IV places both disorders in the same chapter for good reason: they are the commonest before-and-after pair in this field. A patient with centrally mediated pain is prescribed opioids because the pain is severe and unexplained, the pain worsens as doses escalate, and the escalation continues because worsening pain reads as under-treatment. Narcotic bowel syndrome is diagnosed when two of three characteristic patterns appear — pain worsening with continued or escalating doses, a 'soar and crash' relationship to dose timing, or progressive escalation of episode frequency and intensity. The treatment is planned opioid withdrawal, which is the opposite of what the presentation intuitively demands.

Open the Narcotic bowel syndrome calculator →

Centrally Mediated Abdominal Pain (CAPS) vs Rome IV criteria for IBS

Mutually exclusive by mechanism — IBS pain is defined by its relationship to defecation, and CAPS by the absence of that relationship.

IBS requires recurrent abdominal pain related to defecation or to a change in stool frequency or form; CAPS requires no or only occasional relationship to those events. The distinction is not about severity or chronicity but about whether gut events drive the pain. It matters practically because IBS responds to gut-directed treatment — antispasmodics, dietary modification, secretagogues or antidiarrhoeals — while CAPS does not, and treating CAPS as IBS produces a sequence of failed gut-directed trials before anyone reaches the neuromodulator that was always the right answer.

Open the Rome IV criteria for IBS calculator →Keefer L, Drossman DA, Guthrie E, Simrén M, Tillisch K, Olden K, Whorwell PJ. Centrally Mediated Disorders of Gastrointestinal Pain. Gastroenterology. 2016;150(6):1408-1419.

Centrally Mediated Abdominal Pain (CAPS) vs Chronic pain of structural origin

CAPS requires that structural disease does not explain the pain — but a structural diagnosis can coexist if its activity does not account for the symptoms.

This is a subtle and important point that the companion narcotic bowel syndrome criteria state explicitly: a patient may carry a structural diagnosis such as inflammatory bowel disease or chronic pancreatitis while their pain is centrally mediated, provided the character or activity of that disease does not explain it. A patient with quiescent Crohn's disease, normal calprotectin and a normal recent endoscopy who has continuous pain unrelated to bowel events is not experiencing active disease. Recognising this prevents both errors — escalating immunosuppression for pain that is not inflammatory, and dismissing a centrally mediated pain syndrome because a structural label already exists.

Pearls & pitfalls

  • The pain must be dissociated from gut events. A consistent relationship to meals or defecation points to an organ-based functional disorder, not CAPS.
  • Continuous, not episodic. Discrete attacks with well periods in between describe a different disorder.
  • Never prescribe opioids. In this population they cause hyperalgesia and narcotic bowel syndrome, and the intuitive escalation makes the disorder worse.
  • Psychosocial comorbidity is typical but not diagnostic. Its absence does not exclude CAPS and its presence does not establish it — Rome IV states this explicitly.
  • Set the goal as improved function, not abolition of pain, and say so at the start. A patient expecting to be made pain-free will judge effective treatment a failure.
  • Introduce psychological therapy alongside medication, not after it fails. Offering it only at that point reads as a statement that the pain was psychological all along.
  • Schedule regular reviews rather than symptom-triggered visits, which reinforce the pain cycle.
  • 'The pain is not feigned' is a criterion because these patients are so often disbelieved — it is a statement of fact, not an invitation to assess credibility.
  • The exclusion covers other functional disorders too. CAPS is not a label for pain occurring alongside IBS.
  • Explain the neuromodulator as acting on pain signalling rather than mood, or the patient will not take it.

Critical actions

  • Establish that the pain is continuous and does not reliably track eating, defecation or menses — those two features carry the diagnosis.
  • Confirm the organ-based work-up is complete and stop repeating it once it is.
  • Explain central sensitisation concretely, and name the disorder rather than describing what has not been found.
  • Agree function-focused goals explicitly at the outset.
  • Start a central neuromodulator at pain-modulating doses and titrate; explain its mechanism in terms of nerve signalling.
  • Refer for psychological therapy — cognitive behavioural therapy, gut-directed hypnotherapy or mindfulness — alongside, not after, medication.
  • Establish a single point of contact and schedule regular reviews rather than reacting to symptom escalations.
  • Withdraw any opioids already in place, and assess for narcotic bowel syndrome if pain has worsened as doses rose.
  • Screen for and treat depression and anxiety where present, without implying they are the cause.

Why this score exists

Renaming functional abdominal pain syndrome to centrally mediated abdominal pain syndrome was the committee's central move, and it was made to say something specific: the pain has a mechanism, that mechanism is in the central nervous system, and 'functional' had come to be heard by patients and clinicians alike as meaning imaginary. Including 'the pain is not feigned' as a formal criterion is remarkable and tells you how routinely these patients are disbelieved — no other Rome IV disorder finds it necessary to state that the symptom is genuine. The committee was also careful about psychosocial comorbidity, noting it is typical while explicitly refusing to make it diagnostic, which guards against both errors: dismissing CAPS in a patient with no psychiatric history, and diagnosing it in a distressed patient whose pain has an organic cause not yet found.

About the creator

  • Laurie Keefer

    First author, Rome IV centrally mediated disorders committee

    Chaired the committee that produced the Rome IV criteria for centrally mediated disorders of gastrointestinal pain.

  • Douglas A. Drossman

    Co-author; founder of the Rome Foundation

    Contributed much of the underlying work on the biopsychosocial model and on centrally mediated gastrointestinal pain.

  • Peter J. Whorwell

    Co-author; gut-directed hypnotherapy

    Co-authored the chapter and developed much of the evidence base for gut-directed hypnotherapy in functional gastrointestinal pain.

Limitations

  • Entirely clinical, with no biomarker or imaging correlate — central sensitisation is a model rather than a measurable finding in practice.
  • 'No or only occasional relationship' to physiological events is a subjective judgement that patients report inconsistently.
  • 'The pain is not feigned' is unfalsifiable as a criterion and adds nothing operationally, though its inclusion carries a useful message.
  • Requires exclusion of other functional gastrointestinal disorders, which overlap substantially and are themselves defined by consensus.
  • Agreed by committee rather than derived from data, and there is no biomarker or imaging finding that could serve as a reference standard against which to test it.
  • Psychosocial comorbidity is described as typical but explicitly non-diagnostic, leaving its assessment unguided.
  • Says nothing about severity beyond the requirement for functional limitation, and offers no way to track change.
  • The evidence base for treatment is drawn largely from other central pain syndromes rather than from CAPS-specific trials.

If you are the patient

Centrally mediated abdominal pain syndrome means long-standing tummy pain that is present most or all of the time and does not follow a pattern linked to eating or opening your bowels. Scans and camera tests come back normal, and that is expected rather than puzzling — because the problem is not in the structure of the bowel but in how pain signals are processed by the nervous system. A helpful way to think about it is that the volume control on pain has been turned up: signals that would normally be filtered out are being amplified and experienced as constant pain. This is a recognised condition with a real mechanism, and the pain is genuinely there. Treatment works differently from what people expect. Medicines that calm nerve signalling — often the same drugs used as antidepressants, but at lower doses and prescribed for pain rather than mood — are the main option, and psychological therapies such as cognitive behavioural therapy or gut-focused hypnotherapy have good evidence and work best started alongside medication rather than after it. The goal is usually to get you doing more of what matters to you rather than to remove the pain entirely, and that is worth agreeing at the start. One important warning: strong painkillers like morphine or codeine make this condition worse rather than better, and can cause a separate problem where the painkiller itself drives the pain. If you are on them, ask about coming off with support.

Frequently asked questions

What are the Rome IV criteria for CAPS?#

Continuous or nearly continuous abdominal pain; no or only occasional relationship of the pain with physiological events such as eating, defecation or menses; pain that limits some aspect of daily functioning; pain that is not feigned; and pain not explained by another structural or functional gastrointestinal disorder or other medical condition. All fulfilled for three months with onset at least six months earlier.

What does 'centrally mediated' mean?#

That the pain is generated and amplified in the central nervous system rather than driven by events in the gut. The model is central sensitisation with impaired descending inhibition — normal or absent peripheral input is experienced as continuous pain. Rome IV renamed the disorder from 'functional abdominal pain syndrome' specifically to make that mechanism explicit, because 'functional' had come to be heard as meaning imaginary.

How is CAPS different from IBS?#

IBS pain is defined by its relationship to defecation or to a change in stool frequency or form; CAPS requires the absence of any consistent relationship to gut events. The distinction is mechanistic rather than about severity. It matters practically because gut-directed treatments work in IBS and not in CAPS, and treating CAPS as IBS produces a series of failed trials before anyone reaches a neuromodulator.

Why does Rome IV include 'the pain is not feigned' as a criterion?#

Because these patients are so routinely disbelieved. No other Rome IV disorder finds it necessary to state that the symptom is genuine, and its inclusion here is a deliberate statement rather than an operational test. It is not an invitation to assess a patient's credibility — it is an assertion that continuous unexplained abdominal pain is real.

Does CAPS require a psychiatric diagnosis?#

No. Rome IV states that CAPS is typically associated with psychosocial comorbidity but that there is no specific profile that can be used for diagnosis. Its absence does not exclude CAPS, and its presence does not establish it. That wording guards against both dismissing the diagnosis in a patient with no psychiatric history and applying it to a distressed patient whose pain has an organic cause not yet identified.

Why should opioids be avoided in CAPS?#

Because they make it worse. Opioids cause hyperalgesia in a nervous system already failing to inhibit pain signalling, and in this population they frequently produce narcotic bowel syndrome — a distinct Rome IV disorder in which the pain worsens as doses escalate. They also add opioid-induced constipation, which does not develop tolerance. CAPS is one of the few pain syndromes where the intuitive response of escalating analgesia is precisely the wrong move.

What treats centrally mediated abdominal pain?#

Central neuromodulators — tricyclic antidepressants, SNRIs, or combinations — at doses chosen for their effect on pain processing rather than mood, together with psychological therapies such as cognitive behavioural therapy, gut-directed hypnotherapy or mindfulness. Introducing the psychological component alongside medication rather than after it fails matters, because offering it only at that point reads to patients as a statement that the pain was psychological all along.

Can a patient have CAPS alongside a structural diagnosis?#

Yes, provided the structural disease does not explain the pain. A patient with quiescent inflammatory bowel disease, normal inflammatory markers and a normal recent endoscopy who has continuous pain unrelated to bowel events is not experiencing active disease. Recognising this prevents escalating immunosuppression for pain that is not inflammatory, and equally prevents dismissing a centrally mediated pain syndrome because a structural label already exists.

Related calculators

  • Narcotic Bowel Syndrome — Rome IV — opioid-induced hyperalgesia of the gut
  • Rome IV Criteria for IBS — Irritable bowel syndrome diagnosis and subtype
  • Functional Dyspepsia — Rome IV — with PDS and EPS subtyping
  • Functional Chest Pain — Rome IV — non-cardiac, non-reflux chest pain
  • Opioid-Induced Constipation — Rome IV — constipation tied to opioid therapy

References

Original / primary reference

  1. Keefer L, Drossman DA, Guthrie E, Simrén M, Tillisch K, Olden K, Whorwell PJ. Centrally Mediated Disorders of Gastrointestinal Pain. Gastroenterology. 2016;150(6):1408-1419 (Rome IV).

Related disorders

  1. Lacy BE, Mearin F, Chang L, Chey WD, Lembo AJ, Simren M, Spiller R. Bowel Disorders. Gastroenterology. 2016;150(6):1393-1407 (the organ-based functional disorders CAPS must be distinguished from).
  2. Lacy BE, Pimentel M, Brenner DM, et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2021;116(1):17-44.

Last updated August 1, 2026. Clinical knowledge base written and curated by GastroAGI Team from primary medical literature.

Written from primary literature and not yet independently clinically reviewed.

For use by qualified healthcare professionals. This calculator supports clinical judgement and does not replace it.