About the Tokyo Guidelines 2018 (TG18) for Acute Cholecystitis
Local signs plus systemic signs give a suspected diagnosis; adding characteristic imaging makes it definite. Severity then runs top-down: Grade III (severe) is any single organ dysfunction, Grade II (moderate) is any ONE of four criteria — white cell count above 18,000/mm³, a palpable tender right upper quadrant mass, symptoms lasting more than 72 hours, or marked local inflammation — and Grade I is everything else. Two differences from the cholangitis version catch people out: imaging is required for a definite diagnosis here rather than being interchangeable, and Grade II needs one criterion rather than two. The grade is as much a warning about the difficulty of the operation as about the patient.
Formula
Diagnosis: suspected = A + B definite = A + B + C
Severity, assessed in this order:
Grade III = any ONE organ dysfunction
Grade II = any ONE of four criteria (no organ dysfunction)
Grade I = neither of the above- A — local signs of inflammation
- Murphy's sign; or right upper quadrant mass, pain or tenderness.
- B — systemic signs of inflammation
- Fever; elevated CRP; or elevated white cell count. Any one.
- C — imaging
- Findings characteristic of acute cholecystitis. Required for a definite diagnosis, unlike in cholangitis where B and C are interchangeable for suspicion.
- Grade III organ dysfunction
- Cardiovascular, neurological, respiratory, renal, hepatic or haematological, at thresholds identical to the cholangitis criteria. Any one is sufficient.
- Grade II criteria
- WBC above 18,000/mm³; palpable tender RUQ mass; symptoms beyond 72 hours; marked local inflammation. Only ONE is required.
- Grade II requires only ONE criterion here. The cholangitis version requires TWO of its five. The two Tokyo scores are not symmetrical and this is the most consequential difference between them.
- The Grade II white cell threshold is above 18,000/mm³, considerably higher than the 12,000/mm³ used in cholangitis Grade II.
- Duration of symptoms beyond 72 hours is a history item, not a test, and is the criterion most often overlooked. On its own it converts Grade I to Grade II with nothing else changed.
- Imaging is required for a definite diagnosis. A + B without imaging is suspected only.
- TG18 does not specify numeric thresholds for the diagnostic fever, CRP and white cell items, unlike the cholangitis criteria which do. This is a real looseness rather than an omission in this summary.
- Severity is assessed top-down: organ dysfunction is Grade III whatever the Grade II items show, and the counts do not add together.
Interpreting the result
Take the diagnosis and the grade separately. A suspected diagnosis means the criteria as recorded are incomplete, usually because imaging has not yet been done, rather than that the disease is milder. The grade then guides management. Grade I in a fit patient supports early laparoscopic cholecystectomy during the index admission rather than a deferred interval operation. Grade II says the same operation will be harder: this is the point at which the surgeon should plan for a difficult dissection, have a bail-out strategy in mind, and consider whether subtotal cholecystectomy is the safer finish. Grade III means organ dysfunction and demands urgent source control alongside support, with TG18 explicitly permitting either emergency cholecystectomy or percutaneous cholecystostomy depending on the patient's fitness and the expertise available. As with cholangitis, the grade is a snapshot and should be recalculated — the 72-hour criterion alone means a patient can move from Grade I to Grade II purely through the passage of time.
| Score | Band | What it means | Action |
|---|---|---|---|
| Grade I | Mild | No organ dysfunction and none of the four Grade II criteria. A healthy patient with mild gallbladder inflammation | Early laparoscopic cholecystectomy during the index admission in a fit patient, plus antimicrobials |
| Grade II | Moderate | Any one of: WBC above 18,000/mm³, palpable tender RUQ mass, symptoms beyond 72 hours, or marked local inflammation. Predicts a technically difficult cholecystectomy | Early surgical assessment; plan for a hard dissection with a bail-out strategy, or percutaneous cholecystostomy if unfit |
| Grade III | Severe | Dysfunction of any one of six organ systems. The highest-mortality group | Organ support with urgent source control — emergency cholecystectomy or percutaneous cholecystostomy, by fitness and local expertise |
| Criteria not met | Not diagnostic | Does not exclude cholecystitis. TG18 is a diagnostic framework, not a rule-out test | Arrange ultrasound if not already done; imaging is usually the missing item rather than a genuinely negative one |
What the Tokyo Guidelines — Cholecystitis needs (6 inputs)
- A-1: Murphy's sign
- Inspiratory arrest on palpation of the right upper quadrant. A local sign; either A item is sufficient for category A.
- A-2: Right upper quadrant mass, pain or tenderness
- Any of the three counts.
- B-1, B-2, B-3: Fever, elevated CRP, elevated white cell count
- Systemic signs of inflammation. Any one is sufficient for category B. TG18 does not fix numeric thresholds for these diagnostic items, which is a genuine looseness in the criteria.
- C: Imaging findings characteristic of acute cholecystitis
- Gallbladder wall thickening, distension, pericholecystic fluid, a sonographic Murphy's sign, or gallstones and debris. Required for a definite diagnosis — this is where the cholecystitis rule differs from the cholangitis one.
- Organ dysfunction (six systems)
- Cardiovascular (dopamine ≥ 5 µg/kg/min or any noradrenaline), neurological (decreased consciousness), respiratory (PaO₂/FiO₂ below 300), renal (oliguria or creatinine above 2.0 mg/dL), hepatic (PT-INR above 1.5), haematological (platelets below 100,000/mm³). Identical to the cholangitis thresholds. Any one makes it Grade III.
- Grade II criteria (four items)
- White cell count above 18,000/mm³; palpable tender right upper quadrant mass; symptoms lasting more than 72 hours; marked local inflammation (gangrenous or emphysematous cholecystitis, pericholecystic or hepatic abscess, biliary peritonitis). Any ONE makes it Grade II.
Units. The Grade II white cell threshold is expressed as above 18,000/mm³, which is the same as 18 ×10⁹/L — the two conventions appear interchangeably across the guideline. Creatinine above 2.0 mg/dL for renal dysfunction is about 177 µmol/L. The diagnostic fever, CRP and white cell items carry no numeric thresholds in TG18 and depend on local reference ranges.
What it returns
- Diagnostic status
- Definite, suspected, or criteria not met. Suspected is local plus systemic signs; definite additionally requires imaging.
- Severity grade
- Grade I (mild), II (moderate) or III (severe). Assessed top-down, so organ dysfunction settles it regardless of the Grade II items.
- Which organ systems are failing
- Listed explicitly, since Grade III alone does not tell the receiving team what needs supporting.
How it is calculated
The criteria separate the two things that make cholecystitis diagnosable — something wrong locally at the gallbladder, and a systemic inflammatory response — and then require imaging to confirm that the local finding really is the gallbladder. That structure exists because right upper quadrant pain has a long differential: uncomplicated biliary colic produces pain without inflammation, cholangitis produces systemic inflammation with cholestasis rather than local gallbladder signs, and a perforated ulcer or hepatic abscess can mimic both. Requiring one item from each category filters these apart. The severity grading was built around a different question from the cholangitis one. In cholangitis the grade tracks how urgently the biliary tree must be decompressed; in cholecystitis it tracks how difficult and dangerous the operation will be. That is why the Grade II list contains a palpable mass, a duration threshold and specific pathological findings such as gangrene or emphysematous change — these describe a gallbladder that has become hostile to dissect, in a hilum where planes are lost and the bile duct is at risk.
Facts & figures
| Category | Items |
|---|---|
| A — local signs of inflammation | Murphy's sign · right upper quadrant mass, pain or tenderness |
| B — systemic signs of inflammation | Fever · elevated CRP · elevated white cell count |
| C — imaging | Findings characteristic of acute cholecystitis: wall thickening, distension, pericholecystic fluid, sonographic Murphy's sign, stones or debris |
Suspected = one item in A plus one item in B. Definite = A plus B plus C. Unlike the cholangitis criteria, imaging is not interchangeable with another category — it is required for a definite diagnosis.
| Cholangitis | Cholecystitis | |
|---|---|---|
| Suspected diagnosis | A + (B or C) | A + B |
| Definite diagnosis | A + B + C | A + B + C (imaging mandatory) |
| Grade II rule | Any TWO of five | Any ONE of four |
| Grade II white cell threshold | Above 12,000 or below 4,000/mm³ | Above 18,000/mm³ |
| Grade III | Any one of six organ dysfunctions | Identical — same six, same thresholds |
| What the grade drives | Timing of biliary drainage | Timing and difficulty of cholecystectomy |
Grade III is the only part the two share exactly. Everything else differs, which is why they are two calculators rather than one with a toggle.
Evidence
TG18 diagnostic criteria and severity grading — Yokoe et al.
2018The 2018 revision of the Tokyo Guidelines cholecystitis chapter, developed by an international consensus group with accompanying validation of the diagnostic criteria and severity grading against clinical and pathological outcomes.
The criteria retain the TG13 structure with revised supporting evidence, and the severity grading is supported by its association with operative difficulty, conversion rates and mortality.
Management flowchart — Okamoto et al.
2018The TG18 chapter translating the severity grade into a management algorithm, covering the choice between early cholecystectomy, delayed surgery and percutaneous cholecystostomy across the three grades.
Establishes early laparoscopic cholecystectomy as preferred in Grade I and selected Grade II patients, with cholecystostomy reserved for those unfit for surgery, and permits either route at Grade III depending on fitness and expertise.
Surgical management and bail-out strategies — Wakabayashi et al.
2018The TG18 chapter on safe steps in laparoscopic cholecystectomy, addressing the difficult gallbladder that the Grade II criteria describe.
Sets out the critical view of safety and formal bail-out options including subtotal cholecystectomy, which is the practical consequence of a Grade II designation for the operating surgeon.
Pathological correlation
2023Independent study relating TG severity grade to histopathological severity in resected gallbladders.
Supports an association between the TG grade and the degree of pathological inflammation found at surgery, while showing the correlation is imperfect — a reminder that the grade describes the clinical situation rather than the specimen.
How it compares
Tokyo Guidelines — Cholecystitis vs Tokyo Guidelines for acute cholangitis
Different diseases sharing a name — and the Grade II rules differ, one criterion here against two there, which is where they are most often confused.
Cholecystitis is inflammation of the gallbladder, treated by removing or draining it; cholangitis is infection of an obstructed biliary tree, treated by decompressing the duct. The diagnostic criteria differ in structure (imaging is mandatory for a definite cholecystitis diagnosis but interchangeable with cholestasis for suspected cholangitis), and the Grade II rules differ in both the number of criteria required and the white cell threshold. Only Grade III is identical between them. The two can coexist, and when they do, both need addressing separately.
Tokyo Guidelines — Cholecystitis vs Rome IV biliary pain criteria
Opposite ends of the same spectrum — Rome IV defines biliary-type pain without inflammation, TG18 defines the inflamed gallbladder.
Rome IV biliary pain criteria exist to characterise episodic pain of biliary type in a patient who is not acutely inflamed, typically before considering cholecystectomy for functional gallbladder disorder. TG18 requires systemic inflammatory signs and imaging change. A patient meeting Rome IV criteria has, by definition, not got acute cholecystitis at that moment, and the distinction determines whether the operation is urgent or elective.
Tokyo Guidelines — Cholecystitis vs Ultrasound findings alone
Insufficient on their own — imaging is category C, one of three required categories, not the diagnosis.
Gallstones are common and frequently incidental, and wall thickening occurs in ascites, heart failure, hepatitis and hypoalbuminaemia without any cholecystitis. TG18 requires a local sign and a systemic inflammatory sign alongside the imaging precisely so that an incidental ultrasound finding in a patient with another cause for their pain is not mislabelled.
Pearls & pitfalls
- Grade II needs only ONE criterion here, against TWO for cholangitis. Applying the cholangitis rule under-grades cholecystitis and is the commonest cross-contamination between the two scores.
- The Grade II white cell threshold is 18,000/mm³, not the 12,000/mm³ used in cholangitis. A count of 15,000 is not a Grade II criterion in cholecystitis.
- Symptom duration beyond 72 hours is a Grade II criterion on its own. It is a history question rather than a test, and it is the item most often forgotten — a patient can move from Grade I to Grade II with no change in any measurement.
- Imaging is required for a definite diagnosis. A + B alone is suspected, which is a real distinction rather than a formality.
- Read Grade II as a warning about the operation, not only about the patient. It predicts a difficult dissection and a higher risk of bile duct injury.
- Where the dissection is unsafe, subtotal cholecystectomy or conversion is the correct bail-out, not persistence in a hostile hilum. TG18 devotes a chapter to this.
- Consider whether the picture is actually cholangitis. The two coexist, and cholangitis needs biliary rather than gallbladder drainage — draining the gallbladder does not treat an obstructed duct.
- TG18 does not give numeric thresholds for the diagnostic fever, CRP and WBC items. Document the actual values so the assessment can be re-derived by whoever reads the note.
Critical actions
- Grade I in a fit patient: offer early laparoscopic cholecystectomy during the index admission rather than a deferred interval operation.
- Grade II: refer for early surgical assessment and plan for a technically difficult operation with an explicit bail-out strategy.
- Grade III: provide organ support and arrange urgent source control — emergency cholecystectomy or percutaneous cholecystostomy by fitness and local expertise.
- Start antimicrobials and take blood cultures before the first dose in every grade.
- Actively exclude coexisting cholangitis, which requires biliary drainage rather than gallbladder-directed treatment.
- Recalculate the grade during the admission — the 72-hour criterion alone can change it without any other change in the patient.
- Where percutaneous cholecystostomy is used, plan the definitive operation rather than treating the drain as the endpoint.
Why this score exists
The most useful thing to understand about this grading is that it was not built purely as a measure of how ill the patient is. Grade II contains a palpable mass, a 72-hour duration threshold and a list of specific pathological findings — gangrene, emphysematous change, pericholecystic abscess — none of which are physiological markers in the way organ dysfunction is. What they have in common is that each predicts a gallbladder that will be hard and hazardous to remove, with obliterated planes and a bile duct at risk. Reading Grade II as a statement about operative difficulty rather than about sickness explains why a comparatively well patient whose symptoms started four days ago earns the same grade as one with a white cell count of 20,000, and why the guideline pairs the grade with an explicit chapter on bail-out strategies.
About the creator
First author, TG18 cholecystitis diagnostic criteria and severity grading
Led the cholecystitis diagnostic criteria and severity grading chapters of the 2013 and 2018 guidelines.
Co-author of the TG18 cholecystitis diagnostic criteria and severity grading chapter.
Chair of the Tokyo Guidelines revision committee
Led the Tokyo Guidelines programme across the 2007, 2013 and 2018 editions.
Limitations
- The diagnostic items for fever, CRP and white cell count carry no numeric thresholds, unlike the cholangitis criteria, which leaves real interpretive latitude in category B.
- Murphy's sign has modest and operator-dependent sensitivity, particularly in older patients, who are also the group in whom cholecystitis is most likely to be severe.
- The severity grading is consensus-derived rather than fitted to outcome data, so the choice of four Grade II items and the one-of-four rule is expert judgement.
- Grade II mixes a laboratory value, a physical sign, a history item and a set of pathological findings, which means two patients with the same grade can be clinically very different.
- Correlation between the TG grade and histopathological severity is imperfect — the grade describes the clinical situation rather than what is found in the specimen.
- The grading is a snapshot with no representation of trajectory, despite duration being one of its own criteria.
- It does not identify coexisting cholangitis or choledocholithiasis, both of which change management and need separate assessment.
If you are the patient
Acute cholecystitis is inflammation of the gallbladder, usually because a gallstone has blocked its outlet. The Tokyo Guidelines are a checklist doctors use to confirm the diagnosis and then grade how severe it is, from I to III. The diagnosis needs three things: signs of a problem in the right upper part of the abdomen, signs that the body is mounting an inflammatory response, and a scan showing changes in the gallbladder. The grade then helps decide the plan. Grade I usually means keyhole surgery to remove the gallbladder during the same hospital stay, which is generally better than waiting. Grade II means the gallbladder is inflamed enough that the operation is likely to be more difficult, so the surgical team plans accordingly. Grade III means other organs are being affected and the person needs intensive support alongside either surgery or a drain placed into the gallbladder through the skin. One thing worth knowing: if symptoms have been going on for more than three days, that alone moves the grade up, because the longer the inflammation has been present the harder the operation becomes.
Frequently asked questions
What are the Tokyo Guidelines for acute cholecystitis?#
A diagnostic framework plus a severity grade. Diagnosis needs local signs of inflammation (A) and systemic signs (B) for suspicion, with characteristic imaging (C) required to make it definite. Severity is graded I to III.
What defines Grade II acute cholecystitis?#
Any ONE of four criteria, in the absence of organ dysfunction: white cell count above 18,000/mm³, a palpable tender mass in the right upper quadrant, symptoms lasting more than 72 hours, or marked local inflammation such as gangrenous or emphysematous cholecystitis, pericholecystic or hepatic abscess, or biliary peritonitis.
What defines Grade III acute cholecystitis?#
Dysfunction of any one of six organ systems: cardiovascular (dopamine ≥ 5 µg/kg/min or any noradrenaline), neurological (decreased consciousness), respiratory (PaO₂/FiO₂ below 300), renal (oliguria or creatinine above 2.0 mg/dL), hepatic (PT-INR above 1.5), or haematological (platelets below 100,000/mm³). These are identical to the cholangitis Grade III thresholds.
How do the cholecystitis and cholangitis Tokyo criteria differ?#
In three ways that matter. Cholecystitis needs imaging for a definite diagnosis, while cholangitis allows cholestasis and imaging to be interchangeable for suspicion. Cholecystitis Grade II needs one of four criteria; cholangitis needs two of five. And the Grade II white cell threshold is 18,000/mm³ for cholecystitis against 12,000/mm³ for cholangitis. Only Grade III is identical.
Why does symptom duration over 72 hours make it Grade II?#
Because the longer the gallbladder has been inflamed, the more the tissue planes are obliterated and the harder and more hazardous the dissection becomes. The Grade II criteria are as much a prediction of operative difficulty as a measure of how unwell the patient is, which is why a history item sits alongside laboratory and pathological ones.
Should Grade I cholecystitis be operated on during the same admission?#
Yes, in a fit patient. Early laparoscopic cholecystectomy during the index admission is preferred over a deferred interval operation, which is what the TG18 management flowchart supports.
When is percutaneous cholecystostomy used instead of surgery?#
Primarily in patients who are unfit for surgery, most often at Grade III or in Grade II patients with significant comorbidity. TG18 explicitly permits either emergency cholecystectomy or cholecystostomy at Grade III, decided by the patient's fitness and the expertise available. Where a drain is used, the definitive operation should still be planned rather than treating the drain as the endpoint.
Do gallstones on ultrasound confirm acute cholecystitis?#
No. Gallstones are common and often incidental, and gallbladder wall thickening occurs in ascites, heart failure, hepatitis and hypoalbuminaemia without cholecystitis. Imaging is one of three required categories — a local sign and a systemic inflammatory sign are needed alongside it.
References
Original / primary reference
Management
- Okamoto K, Suzuki K, Takada T, et al. Tokyo Guidelines 2018: flowchart for the management of acute cholecystitis. J Hepatobiliary Pancreat Sci. 2018;25(1):55-72.
- Wakabayashi G, Iwashita Y, Hibi T, et al. Tokyo Guidelines 2018: surgical management of acute cholecystitis: safe steps in laparoscopic cholecystectomy for acute cholecystitis. J Hepatobiliary Pancreat Sci. 2018;25(1):73-86.
- Gomi H, Solomkin JS, Schlossberg D, et al. Tokyo Guidelines 2018: antimicrobial therapy for acute cholangitis and cholecystitis. J Hepatobiliary Pancreat Sci. 2018;25(1):3-16.