About the Chicago Classification version 4.0
A deterministic hierarchy, not a score. Start with the median integrated relaxation pressure. If it is raised and peristalsis has failed in every swallow, the answer is achalasia — type II if at least 20% of swallows show panoesophageal pressurisation, type I if not, and type III if there is no normal peristalsis but at least 20% of swallows are premature. A raised IRP with preserved peristalsis points to EGJ outflow obstruction, which version 4.0 declares can never be diagnosed on manometry alone. With a normal IRP, 100% failed peristalsis is absent contractility; at least 20% premature swallows is distal oesophageal spasm; at least 20% of swallows above a DCI of 8000 is hypercontractile oesophagus; and more than 70% ineffective or at least 50% failed swallows is ineffective oesophageal motility. The last three are patterns until compatible symptoms are present.
Formula
Is the median IRP raised?
YES, with 100% failed peristalsis
20% or more panoesophageal pressurisation -> type II achalasia
otherwise -> type I achalasia
YES, no normal peristalsis, 20% or more premature
-> type III achalasia
YES, peristalsis preserved
raised in BOTH positions + 20% or more elevated IBP
+ symptoms + supportive test -> EGJOO (conclusive)
otherwise -> EGJOO pattern (inconclusive)
otherwise -> inconclusive, isolated raised IRP
NO (normal in both positions)
100% failed peristalsis -> absent contractility
20% or more premature -> distal oesophageal spasm *
20% or more swallows DCI above 8000 -> hypercontractile oesophagus *
over 70% ineffective or 50%+ failed -> ineffective oesophageal motility
50-70% ineffective -> inconclusive
otherwise -> normal motility
* requires clinically relevant symptoms to be a diagnosis rather than a pattern- IRP — integrated relaxation pressure
- The median across 10 swallows, measured over the 4 seconds of greatest relaxation within a 10-second window after the swallow. The one metric in version 4.0 whose threshold is not universal.
- DCI — distal contractile integral
- Amplitude times duration times length of the distal contraction, in mmHg·s·cm. The bands are: below 100 failed, 100–450 weak, above 8000 hypercontractile.
- DL — distal latency
- Time from upper oesophageal sphincter relaxation to the contractile deceleration point. Below 4.5 seconds is premature, and premature contractions are what define spasm.
- The 20% rule
- The recurring proportion threshold — for panoesophageal pressurisation, premature contractions, hypercontractile swallows and elevated intrabolus pressure. Two of ten swallows.
- Classification is based on the primary position; secondary position findings and provocative testing are supportive.
- EGJ outflow obstruction is the one category version 4.0 declares can never be conclusive on manometry alone.
- Fragmented peristalsis was deleted as a separate diagnosis and absorbed into ineffective oesophageal motility.
- The normative database expanded from 75 to 469 healthy volunteers between version 3.0 and 4.0, which is what licensed the tighter thresholds.
- Roughly a fifth of patients with achalasia have an IRP below threshold, so a normal IRP does not exclude it.
Interpreting the result
Treat the output as a manometric pattern and check what else it needs. Achalasia of any subtype requires endoscopy before treatment to exclude pseudoachalasia, since a tumour at the cardia reproduces the manometric picture exactly; subtype then guides therapy, with type II responding best to all three treatment options and type III generally favouring POEM because the myotomy can be extended along the spastic segment. An EGJ outflow obstruction pattern needs mechanical obstruction excluded and opioid use reviewed — opioids are a common and reversible cause — and it needs a timed barium oesophagram or FLIP before it is a diagnosis at all. Absent contractility should prompt a look for systemic sclerosis and, if the IRP is borderline, a reconsideration of type I achalasia. Distal oesophageal spasm and hypercontractile oesophagus should be reported as patterns unless the patient has dysphagia or non-cardiac chest pain, and hypercontractility in particular is often a downstream response to an outflow problem rather than a primary disorder. Ineffective oesophageal motility is a minor finding that mostly matters as a marker of reflux disease and as a consideration before antireflux surgery. And a normal study is genuinely informative: functional heartburn, reflux hypersensitivity, globus and functional dysphagia all require normal manometry as part of their Rome IV criteria.
| Score | Band | What it means | Action |
|---|---|---|---|
| Type I achalasia | Raised IRP, 100% failed peristalsis, no pressurisation | Disorder of EGJ outflow with absent contractility | Endoscopy to exclude pseudoachalasia; pneumatic dilatation, Heller myotomy or POEM, with less predictable response than type II |
| Type II achalasia | As type I, plus 20% or more panoesophageal pressurisation | The subtype with the best treatment response | Endoscopy first; responds well to pneumatic dilatation, Heller myotomy and POEM alike |
| Type III achalasia | Raised IRP with 20% or more premature contractions and no normal peristalsis | The spastic subtype, with the least predictable outcome | Endoscopy first; POEM is generally preferred since myotomy length can be tailored to the spastic segment |
| EGJ outflow obstruction — conclusive | Raised IRP both positions, raised IBP, symptoms and supportive test | All three components present | Exclude mechanical obstruction and opioid effect, then treat as a clinically relevant obstruction |
| EGJ outflow obstruction pattern — inconclusive | Manometric pattern without symptoms or without a supportive test | Version 4.0 does not permit a diagnosis on manometry alone | Obtain a timed barium oesophagram or FLIP; do not treat on the pattern alone |
| Inconclusive — isolated raised IRP | IRP raised in one position, or intrabolus pressure not raised | Incomplete pattern | Repeat with provocative testing — multiple rapid swallows and a rapid drink challenge |
| Absent contractility | Normal IRP both positions with 100% failed peristalsis | No contractile activity with a patent junction | Consider type I achalasia if the IRP is borderline; look for systemic sclerosis; manage reflux aggressively |
| Distal oesophageal spasm | Normal IRP with 20% or more premature contractions, plus symptoms | Conclusive only with dysphagia or non-cardiac chest pain | Exclude type III achalasia and opioid effect; treatment options are limited and the evidence thin |
| Hypercontractile oesophagus | Normal IRP with 20% or more swallows above a DCI of 8000, plus symptoms | Threshold raised from 5000 in version 3.0 | Exclude mechanical obstruction and EGJ outflow obstruction first — hypercontractility is often secondary |
| Ineffective oesophageal motility | Over 70% ineffective, or 50% or more failed swallows | A minor disorder, commonly associated with reflux disease | Treat the reflux rather than the manometry; relevant before antireflux surgery |
| Inconclusive — 50 to 70% ineffective | Below the version 4.0 threshold | Would have been reported as IEM under version 3.0 | Use provocative testing to assess peristaltic reserve before concluding |
| Normal oesophageal motility | All metrics within limits | A normal study, which is itself a diagnostic requirement elsewhere | Consider the Rome IV functional oesophageal disorders, all of which require normal manometry |
What the Chicago Classification v4.0 needs (9 inputs)
- Median IRP above the laboratory's upper limit of normal — supine and upright
- Version 4.0 does not specify a single IRP threshold, because it is manufacturer-specific. Commonly cited limits are 15 mmHg supine and 12 mmHg upright for Medtronic systems, and 22 and 15 mmHg for Laborie/Diversatek. Use the limit the reporting laboratory applies. Requiring the upright position at all is new in version 4.0.
- Peristalsis across the 10 wet swallows
- The branch point of the entire classification: 100% failed peristalsis (every swallow with a DCI below 100), no normal peristalsis but premature swallows present, or some normal or ineffective peristalsis preserved.
- Panoesophageal pressurisation in 20% or more swallows
- Isobaric contour of at least 30 mmHg spanning the oesophagus. The only feature separating type II achalasia from type I — and type II has the best treatment response of the three subtypes.
- Premature contractions in 20% or more swallows (DL under 4.5 s with DCI of at least 450)
- Both halves are required. A short distal latency with a DCI below 450 is not a premature contraction in version 4.0 and leaves the study inconclusive rather than spastic.
- Hypercontractile swallows in 20% or more (DCI above 8000)
- Raised from 5000 in version 3.0. This single change substantially reduced how often hypercontractile oesophagus, or jackhammer oesophagus, is reported.
- Proportion of ineffective swallows
- More than 70% ineffective or at least 50% failed meets the criteria; 50–70% ineffective is explicitly inconclusive. Ineffective means a DCI of 100–450, failed means below 100, and fragmented swallows count here — version 4.0 absorbed fragmented peristalsis into this category and deleted it as a separate diagnosis.
- Elevated intrabolus pressure in 20% or more supine swallows
- Isobaric contour of at least 20 mmHg. Required alongside a raised IRP in both positions for the EGJ outflow obstruction pattern.
- Clinically relevant symptoms — dysphagia and/or non-cardiac chest pain
- Version 4.0 requires these before EGJ outflow obstruction, distal oesophageal spasm or hypercontractile oesophagus can be called a diagnosis rather than a manometric pattern.
- Supportive test — timed barium oesophagram or FLIP
- Part of the EGJ outflow obstruction diagnosis rather than an optional extra, because that pattern is always inconclusive on manometry alone.
What it returns
- Manometric pattern
- Deliberately labelled a pattern rather than a diagnosis, because for three of the categories version 4.0 requires clinical information the manometry cannot supply.
- IRP status across both positions
- Reported separately, since an isolated elevation in one position is the commonest route to a spurious EGJ outflow obstruction report.
- Whether the study is conclusive or inconclusive
- Version 4.0 treats an inconclusive study as a legitimate endpoint, with an explicit route onward via provocative testing or a supportive study.
How it is calculated
High-resolution manometry produces a pressure topography plot from which four numbers are extracted per swallow, and the Chicago Classification is the agreed algorithm for turning those numbers into a category. The integrated relaxation pressure asks whether the oesophagogastric junction opens; the distal contractile integral asks how hard the oesophageal body contracts; the distal latency asks whether the contraction arrives in the right sequence or too early; and the proportion of swallows meeting each definition determines whether a finding is a consistent abnormality or noise. The hierarchy runs outflow first, then peristalsis, because an obstruction at the junction changes how the body behaves and would otherwise be misread as a primary contractile disorder. What version 4.0 added on top of that structure is an admission about what the numbers can and cannot establish. Several patterns — an isolated raised IRP, borderline ineffective motility, spasm without symptoms — occur in people who are perfectly well, so the classification now routes them to an inconclusive result with a defined next step rather than assigning a diagnosis the metric cannot support.
Facts & figures
| Element | Version 3.0 | Version 4.0 |
|---|---|---|
| Acquisition protocol | Supine, 10 wet swallows | Supine and upright, with provocative testing |
| EGJ outflow obstruction | Raised IRP with preserved peristalsis | Raised IRP in both positions, raised IBP, plus symptoms and a supportive test |
| Hypercontractile threshold | DCI above 5000 | DCI above 8000 |
| Ineffective oesophageal motility | 50% or more ineffective swallows | Over 70% ineffective, or 50% or more failed |
| Fragmented peristalsis | Separate diagnosis | Deleted; absorbed into IEM |
| Symptom requirement | None | Required for EGJOO, DES and hypercontractile oesophagus |
| Normative database | 75 healthy volunteers | 469 healthy volunteers |
Every change narrows rather than widens. A report generated under version 3.0 can name a disorder that version 4.0 would call inconclusive or normal.
| Metric | Thresholds | What it determines |
|---|---|---|
| IRP (median) | System-specific — commonly 15 mmHg supine and 12 upright (Medtronic); 22 and 15 (Laborie/Diversatek) | Whether the junction opens; the first branch of the hierarchy |
| DCI | Below 100 failed · 100–450 weak · above 8000 hypercontractile | Contractile vigour; separates absent contractility, IEM and hypercontractility |
| DL | Below 4.5 s is premature | Contraction timing; with a DCI of at least 450 it defines spasm and type III achalasia |
| Swallow proportion | 20% for most features; 50% and 70% for IEM | Whether a finding is consistent or incidental |
The IRP is the only one of the four whose threshold varies by equipment, which is why version 4.0 declines to state a single number for it.
Evidence
Derivation — international working group, version 4.0
2021Developed by 52 international experts over two years using formal validated consensus methodology, with a normative database expanded from 75 to 469 healthy volunteers. Published in Neurogastroenterology and Motility in 2021.
Consensus-derived rather than fitted. The expanded normative database is what justified the tighter thresholds, and the explicit conclusive/inconclusive framework was introduced to stop metrics of uncertain significance being reported as diagnoses.
Effect of the revised criteria on reported diagnoses
2021Studies re-applying version 4.0 to cohorts previously classified under version 3.0.
The categories most affected are ineffective oesophageal motility and hypercontractile oesophagus, where a substantial proportion of version 3.0 diagnoses fall below the version 4.0 thresholds, and EGJ outflow obstruction, where requiring both positions plus a supportive test markedly reduces the number of conclusive diagnoses.
How it compares
Chicago Classification v4.0 vs Functional dysphagia
A normal Chicago v4.0 study is a prerequisite for the Rome IV diagnosis, not merely a negative finding.
Rome IV requires the absence of achalasia, EGJ outflow obstruction, distal oesophageal spasm, hypercontractile oesophagus and absent contractility before functional dysphagia can be diagnosed — that is, a normal Chicago Classification. The two frameworks are therefore complementary rather than competing: manometry excludes the structural motor disorders, and Rome IV names what remains. This is also why an over-called version 3.0 diagnosis matters beyond the report itself; it removes a patient from a diagnosis they should have had.
Chicago Classification v4.0 vs Functional chest pain
Hypercontractile oesophagus and distal oesophageal spasm are the two patterns that must be excluded before chest pain is called functional — and both now need symptoms to be diagnosed at all.
There is a circularity worth noticing here. Version 4.0 requires dysphagia or non-cardiac chest pain before hypercontractile oesophagus or distal oesophageal spasm can be diagnosed, while Rome IV requires those manometric disorders to be absent before functional chest pain can be diagnosed. In a patient with chest pain and a spastic pattern, the manometric diagnosis takes precedence; in a patient with chest pain and completely normal manometry, the Rome IV diagnosis applies. The patterns of unclear relevance sit between the two and are best reported as such.
Chicago Classification v4.0 vs Reflux hypersensitivity
Manometry positions the pH probe and excludes motor disease; it does not diagnose either condition.
High-resolution manometry is performed before reflux monitoring in part to locate the lower oesophageal sphincter for accurate probe placement, and in part to exclude the major motor disorders that Rome IV lists as exclusions for every functional oesophageal disorder. Ineffective oesophageal motility is the finding that most often coexists with reflux disease, and it is worth reporting for a practical reason rather than a diagnostic one: impaired clearance raises the risk of dysphagia after antireflux surgery.
Pearls & pitfalls
- There is no single IRP threshold in version 4.0 — it is manufacturer-specific, so use the reporting laboratory's own upper limit of normal.
- The upright position is required in version 4.0, and EGJ outflow obstruction needs the IRP raised in both positions.
- EGJ outflow obstruction can never be conclusive on manometry alone; a supportive test is part of the diagnosis.
- The hypercontractility threshold rose from a DCI of 5000 to 8000 — a version 3.0 jackhammer report may not meet criteria now.
- Ineffective oesophageal motility now needs more than 70% ineffective swallows; 50 to 70% is explicitly inconclusive.
- Fragmented peristalsis no longer exists as a separate diagnosis and is counted within IEM.
- A premature contraction needs both a distal latency below 4.5 seconds and a DCI of at least 450; a short latency with a low DCI is inconclusive.
- About a fifth of patients with achalasia have an IRP below threshold, so a normal IRP does not exclude it.
- Always exclude pseudoachalasia with endoscopy before treating any achalasia subtype.
- Review opioid use before accepting EGJ outflow obstruction or spasm — opioid-induced oesophageal dysfunction reproduces both patterns and is reversible.
- Hypercontractility is frequently secondary to an outflow problem rather than a primary disorder; look at the junction before treating the body.
- An inconclusive study is a legitimate result, not a failed one.
Critical actions
- Confirm the study was acquired in both supine and upright positions, as version 4.0 requires.
- Check which manometry system was used and which IRP upper limit the laboratory applies.
- Verify that a stated conclusion actually follows from the reported metrics, particularly for IEM and hypercontractility.
- Perform endoscopy before treating any achalasia subtype, to exclude pseudoachalasia.
- Review opioid exposure in any patient with an EGJ outflow obstruction or spastic pattern.
- Arrange a timed barium oesophagram or FLIP before accepting EGJ outflow obstruction as a diagnosis.
- Use provocative testing — multiple rapid swallows and a rapid drink challenge — where the study is inconclusive.
- Record patterns of unclear clinical relevance as patterns, not diagnoses, when the patient has no dysphagia or chest pain.
- Consider the Rome IV functional oesophageal disorders when manometry is normal and symptoms persist.
Why this score exists
The most interesting thing version 4.0 did was create a category for not knowing. Diagnostic classifications almost never do this. The pressure on any scheme is to be exhaustive — every study should land somewhere, because a report that ends without a conclusion feels like a failure of the test. Version 4.0 accepted the opposite: an isolated raised IRP, 50 to 70% ineffective swallows, and spasm without symptoms are all now explicitly inconclusive, with a defined next step rather than a label. That was possible because the normative database grew from 75 people to 469, which showed how often these patterns turn up in the healthy. The practical consequence is worth stating plainly to anyone reading a report: an inconclusive study is not a poor-quality one. It means the manometry has been asked a question it cannot answer alone, and the answer lies in a timed barium oesophagram, a FLIP study, or simply in whether the patient has symptoms at all.
About the creator
First author, Chicago Classification version 4.0
Led the international working group that produced version 4.0.
Co-author; originator of the Chicago Classification and of high-resolution manometry metrics
Developed the IRP, DCI and distal latency metrics on which every version of the classification rests.
Co-author; oesophageal physiology
Contributed to version 4.0 and to the Lyon Consensus on reflux testing, which sits alongside it in practice.
Limitations
- Consensus-derived rather than fitted to outcomes, so no category has a measured sensitivity or specificity against a clinical endpoint.
- The IRP threshold is manufacturer-specific, which makes cross-centre and cross-study comparison harder than the single-number metrics suggest.
- About a fifth of patients with achalasia have an IRP below threshold and are missed by the primary branch of the hierarchy.
- The 20% swallow threshold means two of ten swallows can change the category, so the classification is sensitive to the quality of a small number of swallows.
- Manometric patterns and symptoms correlate imperfectly, which is precisely why version 4.0 had to add a symptom requirement to three categories.
- Provocative testing is recommended for inconclusive studies but is not standardised across laboratories.
- The classification says nothing about treatment response beyond the achalasia subtypes.
- Reports generated under earlier versions are not directly comparable, which complicates interpreting a patient's previous studies.
If you are the patient
High-resolution manometry is a test that measures the squeeze of the food pipe and how well the valve at its lower end opens. A thin tube with pressure sensors is passed through the nose into the oesophagus, and you swallow small sips of water while the pressures are recorded. The Chicago Classification is the agreed set of rules for turning those pressure readings into an answer, and version 4.0 is the current one. It works as a series of questions. First: does the valve at the bottom relax properly? If it does not, and the food pipe is not squeezing at all, that is achalasia, which comes in three types that respond differently to treatment. If the valve does not relax but the food pipe still squeezes, that may be an outflow problem — though the rules now say this cannot be confirmed on the pressure test alone, and a barium swallow or a balloon study is needed as well. If the valve is normal, the questions move to the squeeze itself: absent, too early, too strong, or too weak. One thing worth knowing is that an inconclusive result is not a failed test. The newer rules deliberately allow for it, because some pressure patterns turn up in perfectly healthy people, and calling them a disease would be misleading. It simply means another test is needed to settle the question. It is also worth knowing that a completely normal result is genuinely useful: several recognised conditions that cause heartburn, chest pain or a sensation of food sticking can only be diagnosed once this test comes back normal.
Frequently asked questions
What is the Chicago Classification version 4.0?#
The current international scheme for interpreting high-resolution oesophageal manometry, published in 2021. It is a hierarchy rather than a score: the median integrated relaxation pressure is assessed first, then peristalsis, and the combination determines the category — achalasia types I to III, EGJ outflow obstruction, absent contractility, distal oesophageal spasm, hypercontractile oesophagus, ineffective oesophageal motility, or normal.
What changed from version 3.0?#
Every substantive change narrowed a category. Acquisition now requires supine and upright positions; EGJ outflow obstruction requires the IRP raised in both positions plus symptoms plus a supportive test; the hypercontractility threshold rose from a DCI of 5000 to 8000; ineffective oesophageal motility now needs more than 70% ineffective swallows rather than 50%; and fragmented peristalsis was deleted as a separate diagnosis. The normative database also grew from 75 to 469 healthy volunteers.
What is the IRP threshold in version 4.0?#
There isn't one. Version 4.0 makes the point that the threshold is manufacturer-specific, and the commonly cited values differ substantially — around 15 mmHg supine and 12 upright for Medtronic systems, and 22 and 15 mmHg for Laborie/Diversatek. Use the upper limit of normal that the reporting laboratory applies, which is why this calculator asks the question that way.
Why can EGJ outflow obstruction never be diagnosed on manometry alone?#
Because the manometric pattern occurs too often in people without a genuine obstruction. Version 4.0 requires the IRP raised in both supine and upright positions, elevated intrabolus pressure, clinically relevant symptoms, and at least one positive supportive test — a timed barium oesophagram, preferably with a tablet, or a FLIP study. Without all four, the finding is reported as an inconclusive pattern.
What separates the three achalasia subtypes?#
All three need a raised IRP. Type I has 100% failed peristalsis with no pressurisation. Type II has 100% failed peristalsis with panoesophageal pressurisation in at least 20% of swallows. Type III has no normal peristalsis but at least 20% premature contractions. The distinction matters for treatment: type II responds best to all options, and type III generally favours POEM because the myotomy can be tailored to the spastic segment.
Does a normal IRP exclude achalasia?#
No. Roughly a fifth of patients with achalasia have an IRP below the threshold for their system. This is one of the main reasons version 4.0 recommends supportive testing where clinical suspicion is high despite an unremarkable IRP — a timed barium oesophagram or FLIP can establish the diagnosis the manometry missed.
Why do some diagnoses require symptoms?#
Because EGJ outflow obstruction, distal oesophageal spasm and hypercontractile oesophagus all occur in people with no oesophageal complaints. Version 4.0 requires dysphagia and/or non-cardiac chest pain before these are called diagnoses rather than manometric patterns, so that an incidental finding does not become a condition to be treated.
What does an inconclusive study mean?#
That the metrics do not support a diagnosis on their own, which version 4.0 treats as a legitimate outcome rather than a failure. The three commonest are an isolated raised IRP in one position, 50 to 70% ineffective swallows, and a spastic or hypercontractile pattern without symptoms. Each has a defined next step — provocative testing, a timed barium oesophagram, or simply clinical reassessment.
Should an older manometry report be reinterpreted under version 4.0?#
It is worth doing where the diagnosis is driving management. The categories most likely to change are ineffective oesophageal motility and hypercontractile oesophagus, both of which had lower thresholds under version 3.0, and EGJ outflow obstruction, which now requires far more than a raised supine IRP. A patient carrying one of those labels from an older study may not meet current criteria.
References
Original / primary reference
Related consensus documents
- Gyawali CP, Yadlapati R, Fass R, Katzka D, Pandolfino J, Savarino E, et al. Updates to the modern diagnosis of GERD: Lyon consensus 2.0. Gut. 2024;73(2):361-371.
- Aziz Q, Fass R, Gyawali CP, Miwa H, Pandolfino JE, Zerbib F. Esophageal Disorders. Gastroenterology. 2016;150(6):1368-1379 (Rome IV — the functional disorders that require normal manometry).