Acute Cholecystitis

1. Overview
2. Pathophysiology
3. Calculous vs Acalculous Cholecystitis
4. Risk Factors
5. Clinical Presentation and Murphy's Sign
6. Diagnosis
7. Tokyo Guidelines Severity Grading
8. Treatment and Management
9. Complications
10. Research Papers
11. Connections
12. Featured Videos

Overview

Acute cholecystitis is acute inflammation of the gallbladder, most often triggered by a gallstone impacted in the cystic duct. It affects approximately 200,000 Americans annually and is the second most common indication for emergency abdominal surgery after appendicitis.

The vast majority of cases — 90–95% — are calculous cholecystitis, where an obstructing stone causes bile stasis and a cascade of chemical irritation, mucosal injury, and secondary bacterial infection. The remaining 5–10% are acalculous, arising in critically ill patients without stones, and carry a significantly higher mortality.

Outcomes are generally favorable when recognized early. Most patients respond well to intravenous antibiotics combined with early laparoscopic cholecystectomy (lapchole), typically performed within 72 hours of symptom onset. The Tokyo Guidelines (TG18) provide an internationally adopted framework for grading severity and directing treatment decisions.

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Pathophysiology

Calculous Cholecystitis

In calculous cholecystitis, a gallstone becomes impacted in the cystic duct or Hartmann's pouch, the infundibular outpouching of the gallbladder neck. Obstruction halts normal bile outflow, producing:

1. Bile stasis and concentration — trapped bile grows increasingly concentrated, raising the local concentration of cytotoxic bile salts.
2. Chemical irritation — concentrated bile salts disrupt the gallbladder mucosal barrier, triggering prostaglandin (PGE₂, PGI₂) release and inflammatory mediator cascades.
3. Mucosal injury and edema — the gallbladder wall becomes edematous, hyperemic, and infiltrated with neutrophils.
4. Secondary bacterial infection — bacterobilia develops in 50–75% of cases. Common organisms include Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, and anaerobes such as Bacteroides fragilis. Infection amplifies inflammation and raises the risk of gangrenous progression and perforation.

Acalculous Cholecystitis

Acalculous cholecystitis occurs without stones in the setting of critical illness, major trauma, burns, sepsis, or prolonged total parenteral nutrition (TPN). Two converging mechanisms drive it:

• Biliary stasis — fasting, opioid analgesics, and TPN suppress cholecystokinin (CCK) release, reducing gallbladder contractility. Stagnant bile becomes viscous and concentrated ("biliary sludge").
• Ischemia — low-flow states, vasopressors, and microvascular injury reduce gallbladder wall perfusion. Ischemia-reperfusion injury further damages the mucosal barrier.

Because these patients are often sedated or have an altered sensorium, diagnosis is frequently delayed, contributing to the 30–50% mortality seen in acalculous disease — far higher than the 1–3% mortality of uncomplicated calculous cholecystitis.

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Calculous vs Acalculous Cholecystitis

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Risk Factors

The classic mnemonic for gallstone disease — and by extension calculous cholecystitis — is the "5 F's":

• Female — estrogen increases cholesterol secretion into bile and reduces bile acid synthesis; progesterone slows gallbladder emptying. Cholecystitis is approximately twice as common in women as in men.
• Forty — prevalence rises steeply after age 40; peaks in the sixth and seventh decades.
• Fat — obesity (BMI >30) increases biliary cholesterol saturation and reduces gallbladder motility.
• Fertile — pregnancy and multiparity amplify hormonal effects, increase bile cholesterol, and reduce gallbladder emptying.
• Family history — first-degree relatives of gallstone patients carry a 2–3× increased lifetime risk.

Additional independent risk factors include:

• Rapid weight loss — crash dieting or bariatric surgery mobilizes hepatic cholesterol into bile faster than gallbladder motility can clear it.
• Total parenteral nutrition (TPN) — bypasses enteral stimulation of CCK; gallbladder stasis within days.
• Prolonged fasting — similar mechanism to TPN.
• Diabetes mellitus — autonomic neuropathy impairs gallbladder motility; diabetics have higher rates of gangrenous cholecystitis and acalculous disease.
• Critical illness, major trauma, burns — primary drivers of acalculous disease (see above).
• Immunosuppression — organ transplant recipients have elevated rates of acalculous and complicated cholecystitis.
• Crohn's disease — terminal ileal disease or resection reduces bile acid reabsorption, increasing biliary cholesterol saturation and stone risk.
• Hemolytic anemias (sickle cell disease, hereditary spherocytosis) — pigment (bilirubin) stone formation increases cholecystitis risk, particularly in younger patients.

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Clinical Presentation and Murphy's Sign

Symptoms

Unlike biliary colic — which is episodic, lasts under 6 hours, and resolves completely — acute cholecystitis presents with persistent right upper quadrant (RUQ) pain lasting more than 6 hours, typically accompanied by systemic features of inflammation.

• RUQ or epigastric pain — constant and progressive (not colicky); often radiates to the right shoulder, right scapula, or interscapular area via phrenic nerve and diaphragmatic irritation.
• Fever — typically >38.5°C; high-grade fever (>39°C) suggests gangrenous disease or concurrent cholangitis.
• Nausea and vomiting — present in the majority of patients.
• Anorexia — universal.

Murphy's Sign

Murphy's sign is the cornerstone physical examination finding in acute cholecystitis:

The examiner places two fingers in the RUQ below the liver edge, then asks the patient to take a deep breath. As the diaphragm descends, the inflamed gallbladder moves inferiorly against the examiner's fingers. The patient involuntarily arrests inspiration due to sharp pain — a positive Murphy's sign.

• Sensitivity: ~65%
• Specificity: ~87%
• The sonographic Murphy's sign (maximal pain directly under the ultrasound probe positioned over the gallbladder) has somewhat better diagnostic value and can be elicited in sedated patients by noting facial grimacing.

Boas Sign

Referred hyperesthesia in the right subscapular area (approximately the right T9 dermatome), caused by phrenic nerve irritation from the inflamed gallbladder. Less commonly elicited than Murphy's sign but specific when present.

Distinguishing Acute Cholecystitis from Biliary Colic

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Diagnosis

Laboratory Findings

• Leukocytosis — WBC >10,000/mm³; >18,000 suggests Grade II severity per TG18.
• Elevated CRP — sensitive marker of acute-phase inflammation; useful for severity grading and monitoring treatment response.
• Alkaline phosphatase — mildly elevated from biliary obstruction and hepatic inflammation.
• Bilirubin — mild elevation is common; significant hyperbilirubinemia (>3–4 mg/dL) raises suspicion for concurrent common bile duct stone (choledocholithiasis) or Mirizzi syndrome.
• Liver enzymes (AST/ALT) — modest elevation possible; marked elevation suggests hepatitis or cholangitis.
• Lipase/amylase — elevated if concurrent gallstone pancreatitis.

Ultrasound — First-Line Imaging

Abdominal ultrasound is the first-line imaging modality for suspected cholecystitis: it is rapid, inexpensive, portable, and avoids radiation. Diagnostic criteria include:

• Gallstones or biliary sludge in the gallbladder lumen
• Gallbladder wall thickening >3 mm
• Pericholecystic fluid (edema around the gallbladder)
• Sonographic Murphy's sign — pain maximal directly under the transducer when pressed over the gallbladder (sensitivity ~86%, specificity ~35%)
• Gallbladder distension (>5 cm transverse diameter)

HIDA Scan (Hepatobiliary Scintigraphy)

The HIDA scan (hepatobiliary iminodiacetic acid scintigraphy) is indicated when ultrasound findings are equivocal. A technetium-99m-labeled iminodiacetic acid derivative is injected intravenously. The radiotracer is concentrated by hepatocytes and excreted into bile. Under normal conditions, it fills the gallbladder within 30–60 minutes.

Non-visualization of the gallbladder at 60 minutes (or 4 hours after morphine augmentation) indicates cystic duct obstruction, consistent with cholecystitis.

• Sensitivity: ~97%
• Specificity: ~90%
• False-positives occur with prolonged fasting, TPN, or liver disease.

CT and MRCP

• CT abdomen/pelvis — preferred when complications are suspected: gallbladder perforation, emphysematous cholecystitis (gas in gallbladder wall), pericholecystic abscess, or when the diagnosis is uncertain and appendicitis or other pathology must be excluded.
• MRCP (magnetic resonance cholangiopancreatography) — non-invasive evaluation of the biliary tree when choledocholithiasis, Mirizzi syndrome, or primary sclerosing cholangitis is suspected.

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Tokyo Guidelines Severity Grading

The Tokyo Guidelines, first published in 2007 and most recently updated as TG18 in 2018, provide the internationally accepted framework for grading acute cholecystitis severity and matching patients to appropriate treatment pathways.

Grade I — Mild

Acute cholecystitis in a patient with no organ dysfunction and local inflammation confined to the gallbladder. The patient is fit for surgery.

• No criteria for Grade II or III are met.
• First-line treatment: early laparoscopic cholecystectomy within 72 hours of symptom onset.

Grade II — Moderate

Acute cholecystitis associated with marked local inflammation, defined by any one of the following:

• Leukocytosis >18,000/mm³
• Fever >39°C
• Palpable tender mass in the RUQ
• Symptom duration >72 hours
• Marked local inflammation on imaging: gangrenous cholecystitis, pericholecystic abscess, hepatic abscess, biliary peritonitis, emphysematous cholecystitis, bilioenteric fistula

Grade II patients may still proceed to early lapchole if performed at an experienced center; if the local inflammatory process is severe or the patient's condition is suboptimal, delayed surgery after initial medical management is acceptable.

Grade III — Severe

Acute cholecystitis with organ dysfunction in one or more systems:

Grade III patients require immediate intensive care support and organ stabilization. Definitive cholecystectomy is deferred. Percutaneous cholecystostomy (PC) is often used as a bridge to reduce gallbladder pressure and systemic inflammation while the patient is stabilized for eventual elective surgery.

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Treatment and Management

Initial Medical Management

All patients with acute cholecystitis require:

• NPO (nothing by mouth) — reduces biliary stimulation and prepares for possible surgery.
• Intravenous fluid resuscitation — corrects dehydration from fever, vomiting, and reduced oral intake.
• Analgesics — opioids or ketorolac for pain control. Historical concerns that opioids worsen biliary spasm (the "morphine myth") have not been borne out clinically.
• Antibiotic therapy — targeting gram-negative enteric organisms and anaerobes:

Laparoscopic Cholecystectomy — Definitive Treatment

Early laparoscopic cholecystectomy (within 72 hours) is the standard of care for Grade I and most Grade II patients. Multiple randomized controlled trials and systematic reviews, including the landmark Cochrane analysis by Gurusamy et al. (2013), confirm that early surgery reduces:

• Total hospital length of stay
• Conversion rate from laparoscopic to open procedure
• Overall complication rates
• Risk of recurrent biliary events during a "waiting period"

The conversion rate from laparoscopic to open cholecystectomy is approximately 5–10%, higher when surgery is delayed beyond 72 hours due to increased adhesions and tissue friability.

Percutaneous Cholecystostomy (PC)

For Grade III patients or high-surgical-risk patients (severe comorbidities, ASA class IV–V), percutaneous cholecystostomy provides a temporizing bridge:

• Ultrasound- or CT-guided placement of a drainage catheter directly into the gallbladder lumen under local anesthesia.
• Decompresses the gallbladder, reduces intraluminal pressure, and allows infected bile to drain.
• Clinical improvement typically seen within 24–48 hours.
• The CHOCOLATE trial (Loozen et al., BMJ 2018) compared PC to lapchole in high-risk patients; both were feasible, though lapchole had lower rates of major complications in selected patients.
• After patient stabilization (weeks to months), elective interval cholecystectomy is performed — or the gallbladder is left in situ in truly inoperable patients if the tube can be removed once the cystic duct is unobstructed.

Open Cholecystectomy

Open surgery is reserved for cases where laparoscopic approach is not feasible: gallbladder perforation with biliary peritonitis, dense adhesions from prior surgeries, inability to identify critical anatomy (Calot's triangle), or intraoperative complications.

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Complications

Gangrenous Cholecystitis

Ischemic necrosis of the gallbladder wall, occurring in approximately 2–20% of acute cholecystitis cases — the most feared acute complication. Risk factors include diabetes, cardiovascular disease, delayed presentation, and male sex. CT shows absent or heterogeneous enhancement of the gallbladder wall. Gangrenous cholecystitis dramatically increases perforation risk and mandates urgent surgical intervention regardless of TG18 grade.

Gallbladder Perforation

Perforation occurs in roughly 5–10% of cases and presents in three patterns (Niemeier classification):

• Type I (acute free perforation) — bile leaks into the peritoneal cavity → bile peritonitis → surgical emergency with high mortality.
• Type II (subacute) — perforation is walled off by omentum and adjacent structures → pericholecystic abscess; presents with persistent fever and a palpable RUQ mass.
• Type III (chronic) — perforation into an adjacent hollow organ (duodenum, colon) → bilioenteric fistula; may cause gallstone ileus.

Emphysematous Cholecystitis

A rare but life-threatening variant (1–2% of cases) caused by gas-forming organisms — most commonly Clostridium perfringens, E. coli, or Klebsiella — infecting the gallbladder wall. CT demonstrates gas within the gallbladder wall or lumen. Predominantly affects elderly diabetic men. Perforation rate approaches 20–75%. This is a surgical emergency; early cholecystectomy or PC is imperative.

Cholecystoenteric Fistula

Erosion of a large gallstone through the gallbladder wall into an adjacent bowel loop — most often the duodenum (cholecystoduodenal fistula), less commonly the colon or stomach. Can produce gallstone ileus if the stone (typically >2.5 cm) impacts in the terminal ileum. Presents as small-bowel obstruction with air in the biliary tree (pneumobilia) on plain film or CT (Rigler's triad).

Mirizzi Syndrome

A stone impacted in the cystic duct or Hartmann's pouch exerts external compression on the common hepatic or common bile duct (CBD), producing obstructive jaundice that can mimic cholangiocarcinoma. MRCP or ERCP is required for diagnosis. Surgical management is complex and should be performed at experienced hepatobiliary centers.

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Research Papers

1. Yokoe M, Hata J, Takada T, et al. "Tokyo Guidelines 2018: diagnostic criteria and severity grading of acute cholecystitis." J Hepatobiliary Pancreat Sci. 2018;25(1):41–54. PMID: 29032636
2. Miura F, Okamoto K, Takada T, et al. "Tokyo Guidelines 2018: initial management of acute biliary infection and flowchart for acute cholangitis." J Hepatobiliary Pancreat Sci. 2018;25(1):31–40. PMID: 29019233
3. Gurusamy K, Davidson C, Gluud C, Davidson BR. "Early versus delayed laparoscopic cholecystectomy for people with acute cholecystitis." Cochrane Database Syst Rev. 2013;6:CD005440. PMID: 23813477
4. de Mestral C, Rotstein OD, Laupacis A, et al. "Comparative operative outcomes of early and delayed cholecystectomy for acute cholecystitis." Ann Surg. 2014;259(1):10–15. PMID: 23756456
5. Loozen CS, van Ramshorst B, van Santvoort HC, Boerma D. "Laparoscopic cholecystectomy versus percutaneous catheter drainage for acute cholecystitis in high-risk patients (CHOCOLATE): multicentre randomised clinical trial." BMJ. 2018;363:k3965. PMID: 30530525
6. Yamashita Y, Takada T, Kawarada Y, et al. "Backgrounds of the Tokyo Guidelines for the management of acute cholangitis and cholecystitis." J Hepatobiliary Pancreat Surg. 2007;14(1):1–10. PMID: 17252291
7. Strasberg SM. "Acute calculous cholecystitis." N Engl J Med. 2008;358(26):2804–2811. PMID: 18579815
8. Huffman JL, Schenker S. "Acute acalculous cholecystitis: a review." Clin Gastroenterol Hepatol. 2010;8(1):15–22. PMID: 19747982
9. Banz V, Gsponer T, Candinas D, Güller U. "Discrepancy between the pre- and intraoperative diagnosis of acute cholecystitis." Surg Endosc. 2011;25(3):894–901. PMID: 20734091
10. Wakabayashi G, Iwashita Y, Hibi T, et al. "Recommendations for laparoscopic and open cholecystectomy: Tokyo Guidelines 2018." J Hepatobiliary Pancreat Sci. 2018;25(1):73–86. PMID: 29045089
11. Kimura Y, Takada T, Kawarada Y, et al. "Definitions, pathophysiology, and epidemiology of acute cholangitis and cholecystitis: Tokyo Guidelines." J Hepatobiliary Pancreat Surg. 2007;14(1):15–26. PMID: 17252293
12. Navez B, Mutter D, Russier Y, et al. "Laparoscopic approach improves short-term outcome of patients with acute cholecystitis." World J Surg. 1997;21(9):899–904. PMID: 9301927

PubMed Topic Searches

1. Acute cholecystitis laparoscopic cholecystectomy
2. Tokyo Guidelines cholecystitis severity grading
3. Acalculous cholecystitis ICU critical illness
4. Percutaneous cholecystostomy high-risk surgical patients
5. Emphysematous cholecystitis diagnosis and treatment

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Connections

• Gastroenterology
• Gallstones
• Choledocholithiasis
• Cholangitis
• Pancreatitis
• Primary Sclerosing Cholangitis
• Gallbladder Disease

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