Acalculous Cholecystitis

Acute acalculous cholecystitis (AAC) is acute inflammation of the gallbladder without gallstones, accounting for 5–10% of all acute cholecystitis cases. [1] It predominantly affects critically ill patients and carries a historically high mortality (~30%), though early diagnosis and intervention significantly improve outcomes. [2-3] The pathogenesis centers on gallbladder ischemia and bile stasis rather than stone obstruction, with nonobstructive mechanisms (ischemia-reperfusion injury, eicosanoid-mediated inflammation) being the central drivers. [3-4]

• RUQ pain: Onset, radiation (to right shoulder/scapula), relationship to meals, severity, and progression
• Fever, nausea, vomiting: Classic triad alongside RUQ pain [1]
• ICU context: Duration of critical illness, recent surgery/trauma, prolonged fasting, TPN use, mechanical ventilation, vasopressor requirement [2][5]
• Outpatient context: Recent viral illness (especially in children — EBV, hepatitis A), autoimmune/rheumatic disease [6-7]
• Important negatives: Absence of prior gallstone history, no biliary colic episodes, no prior cholecystectomy
• Pearl: In sedated/intubated ICU patients, AAC often presents as unexplained sepsis, rising WBC, or new organ dysfunction rather than classic biliary symptoms [4][8]

• Unexplained sepsis or septic shock in a critically ill patient — must consider AAC [4]
• Peritoneal signs (guarding, rigidity) — suggests perforation or gangrenous cholecystitis
• Rapid clinical deterioration despite broad-spectrum antibiotics
• Gangrenous cholecystitis occurs at a significantly higher rate in AAC vs. calculous cholecystitis (31.2% vs. 5.6%) [9]
• Gallbladder perforation risk is high if diagnosis is delayed [8]
• Myocardial infarction/CHF is the only independent risk factor for in-hospital death in AAC [10]

• Contributors: Opioids (promote bile stasis), vasopressors (splanchnic ischemia), TPN [3]
• Empiric antibiotics:
  • Not critically ill: Amoxicillin/clavulanate (if local Enterobacteriaceae resistance <20%) [11]
  • Critically ill: Piperacillin/tazobactam [11]
  • Beta-lactam allergy: Ciprofloxacin or amikacin + metronidazole [11]
  • ESBL risk: Ertapenem or tigecycline; meropenem reserved for septic shock with ESBL risk [11]
• Contraindicated: Avoid hepatotoxic agents; aminoglycoside courses should be brief due to increased nephrotoxicity risk during cholestasis [12]

• NPO during acute illness and pending surgical decision
• Avoid TPN if possible — TPN is a recognized risk factor for AAC; transition to enteral feeding as soon as clinically feasible [3][5]
• Long-term: Low-fat diet if gallbladder preserved; standard diet post-cholecystectomy
• Adequate hydration to support hemodynamics and prevent further splanchnic ischemia

• GI: Nausea, vomiting, anorexia, abdominal distension, jaundice, change in stool color
• Constitutional: Fever, chills, rigors, malaise
• Cardiovascular: Hypotension, tachycardia (signs of sepsis/shock)
• Respiratory: Dyspnea, pleuritic right-sided chest pain (referred pain or reactive effusion)
• Neurologic: Altered mental status (may be only sign in ICU patients)
• Infectious: Recent viral illness, HIV status, immunosuppression

• Collateral: ICU nursing observations (abdominal distension, feeding intolerance, rising vasopressor requirements), medication administration record (opioids, TPN duration)
• Family history: Generally not contributory; no strong hereditary component
• Social context: Immunosuppression (HIV/AIDS — AAC associated with CMV, Cryptosporidium cholangiopathy), alcohol use, IV drug use

• Critical illness: Trauma, major surgery, burns, sepsis, shock, cardiac arrest [2-3]
• Prolonged ICU stay: Mechanical ventilation, vasopressor use, TPN, prolonged fasting [5]
• Comorbidities: Diabetes mellitus, CHF, atherosclerotic disease, cerebrovascular accident, malignancy, abdominal vasculitis, cholesterol embolization [3][9]
• Age: Risk increases significantly in patients >50 years (92.8% of AAC patients in one series) [9]
• Immunosuppression: HIV/AIDS, bone marrow transplant, chemotherapy [7]
• Pediatric: Viral infections (EBV, hepatitis A, enteroviruses) are the most common trigger [7]

• Acute calculous cholecystitis — most common mimic; distinguished by presence of gallstones on imaging
• Ascending cholangitis — Charcot's triad (fever, jaundice, RUQ pain); CBD dilation on imaging
• Hepatic abscess — fever, RUQ pain; CT with rim-enhancing collection
• Acute pancreatitis — epigastric pain radiating to back, elevated lipase
• Peptic ulcer disease/perforation — epigastric pain, free air on imaging
• Right lower lobe pneumonia — referred RUQ pain, cough, CXR findings
• Fitz-Hugh-Curtis syndrome — RUQ pain in young women, perihepatitis
• Mesenteric ischemia — pain out of proportion to exam in vascular patients; lactate elevation
• Appendicitis (high-riding cecum) — can mimic RUQ pathology
• Pearl: In ICU patients, the differential for unexplained sepsis is broad — AAC should be considered when other sources are excluded [4]

• Prior episodes of cholecystitis or biliary disease
• Recent surgery, trauma, or ICU admission
• Chronic illnesses: DM, CHF, CKD, CVA, malignancy, HIV/AIDS [3][9]
• Vascular disease (atherosclerosis, vasculitis)
• Prior cholecystectomy (rules out diagnosis)
• Immunosuppressive medications or transplant history

• Vital signs: Fever, tachycardia, hypotension (sepsis)
• RUQ tenderness with or without guarding
• Murphy's sign: Positive (inspiratory arrest with RUQ palpation) — but often difficult to elicit in sedated/intubated patients [8][13]
• Abdominal distension, decreased bowel sounds
• Jaundice: Present in minority; suggests concomitant biliary obstruction or severe inflammation
• Peritoneal signs: Rebound, rigidity — suggest perforation or gangrenous cholecystitis
• Pearl: In ICU patients, physical exam is often unreliable; maintain a high index of suspicion based on clinical trajectory [2]

• CBC: Leukocytosis with left shift (nonspecific but expected)
• CMP/LFTs: Mild transaminase elevation (cytolysis), possible mild bilirubin elevation; cholestasis pattern less common [5]
• Lipase: To rule out pancreatitis
• Lactate: Elevated in sepsis/ischemia
• Blood cultures: Before initiating antibiotics
• CRP/Procalcitonin: Inflammatory markers to trend
• Coagulation studies: Pre-procedural assessment
• NLR (neutrophil-to-lymphocyte ratio): Elevated NLR and lower lymphocyte counts correlate with higher severity (Grade III) [14]
• Pearl: Lab findings are nonspecific — the diagnosis rests on the combination of clinical suspicion + imaging [2]

• First-line: Right upper quadrant ultrasound [1][13]
  • Gallbladder wall thickening >3 mm (some reports up to 3.5–9 mm)
  • Gallbladder distension (short-axis diameter >40 mm)
  • Pericholecystic fluid
  • Sludge without stones
  • Sonographic Murphy's sign (limited utility in sedated patients)
  • Sensitivity ~81%, specificity ~83% for acute cholecystitis [1]
• CT abdomen: Comparable accuracy; useful when ultrasound is equivocal or to evaluate complications (perforation, abscess) [4]
• Gold standard: Hepatobiliary iminodiacetic acid (HIDA) scan — non-filling of gallbladder at 4 hours; accuracy up to 95%. However, may not be practical in critically ill patients and can yield false positives in ICU patients on TPN or fasting [1-2][13]
• When imaging is unnecessary: If clinical picture is clear and patient is going to OR
• Pearl: Many sonographic features of AAC (wall thickening, distension, sludge) may be routinely present in ICU patients without cholecystitis — serial imaging and clinical correlation are essential [13]

• Tokyo Guidelines (TG18) Severity Grading: [10][15]
  • Grade I (mild): No organ dysfunction, mild inflammatory changes
  • Grade II (moderate): Elevated WBC >18,000, palpable RUQ mass, symptom duration >72 hours, marked local inflammation
  • Grade III (severe): Organ dysfunction (cardiovascular, neurologic, respiratory, renal, hepatic, hematologic)
• Charlson Comorbidity Index (CCI): CCI ≥4 identifies poor surgical candidates [15]
• ASA Physical Status: ASA ≥3 suggests high perioperative risk [15]
• Point-of-care ultrasound (POCUS): Can provide additional bedside information, though the Society of Critical Care Medicine suggests intensivists should not perform the definitive exam for cholecystitis diagnosis [13]
• Bile culture: Obtained at time of cholecystostomy or cholecystectomy to guide antibiotic therapy

• Indications: All patients with suspected AAC, particularly given the association with MI/CHF as a risk factor and cause of death [10]
• Evaluate for acute coronary syndrome as a mimic or precipitant of AAC
• ST changes, arrhythmias, or signs of right heart strain may be present in critically ill patients
• Pearl: MI/CHF was the only independent risk factor for in-hospital death in a large AAC series [10]

AAC is a life-threatening condition with a high risk of gangrenous cholecystitis (31% vs. 6% in calculous disease) and perforation if untreated. [8-9] It represents a systemic disease manifestation rather than a local gallbladder process. [16] Two distinct populations are affected:

• ICU patients: Critically ill with ischemia/stasis-driven pathology; subtle presentation; high mortality
• Outpatient/community patients: Often viral or autoimmune etiology; may have a more benign course amenable to conservative management [6]

Severity stratification per Tokyo Guidelines helps guide management decisions. [10][15] Overall in-hospital mortality is approximately 2.5% in contemporary series, though historically reported as high as 30% in critically ill cohorts. [3][10]

Initial stabilization

• IV fluid resuscitation, electrolyte correction
• NPO status
• Broad-spectrum IV antibiotics (see Medications section above) [11]
• Analgesics (avoid opioids if possible given bile stasis risk)

Definitive treatment

• Laparoscopic cholecystectomy is the gold standard, ideally within 1–3 days of diagnosis [1][10]
  • Early cholecystectomy: fewer complications (11.8% vs. 34.4%), shorter LOS (5.4 vs. 10.0 days) [1]
  • Laparoscopic approach preferred over open, with superior outcomes [10]
• Percutaneous cholecystostomy (PC): Reserved for patients who are severely ill and poor surgical candidates (ASA ≥3, CCI ≥4, septic shock) [1][15]
  • Controls disease in ~85% of patients [3]
  • Higher complication rate than cholecystectomy (65% vs. 12% in one RCT) [1]
  • Can serve as bridge to interval cholecystectomy (8–13 weeks) or as definitive therapy if patient remains a non-surgical candidate [15]
  • Interval cholecystectomy may not be necessary in AAC survivors if stones are absent and precipitating condition resolves [3][17]
• EUS-guided gallbladder drainage: Emerging option for non-surgical candidates; avoids external drain complications [8]
• Conservative management (antibiotics alone): May be appropriate for viral or rheumatic disease-associated AAC; recurrence rate ~9.8% over long-term follow-up [6][18]

The following figure from a JAMA Surgery systematic review illustrates a proposed algorithm for managing acute cholecystitis, including percutaneous cholecystostomy indications and management:

• Admit all patients with confirmed or suspected AAC — this is not an outpatient diagnosis
• ICU admission: Sepsis, hemodynamic instability, organ dysfunction (TG18 Grade III), need for vasopressors [5][10]
• Surgical floor: Hemodynamically stable patients awaiting cholecystectomy
• Surgical consultation: Mandatory in all cases [1]
• Interventional radiology consultation: If percutaneous cholecystostomy is indicated
• GI consultation: Consider for EUS-guided drainage in non-surgical candidates [8]
• Discharge criteria: Post-cholecystectomy — tolerating diet, pain controlled, afebrile, no signs of complications

• Post-cholecystectomy: Surgical follow-up in 2–4 weeks; wound check, pathology review
• Post-cholecystostomy tube: Close follow-up for tube management; interval cholecystectomy typically at 8–13 weeks if patient becomes a surgical candidate; clamping trial preferred over cholangiogram for tube removal decisions [15]
• Conservatively managed patients: Follow-up imaging in 4–6 weeks; recurrence rate ~9.8% over ~5.7 years; low threshold for re-evaluation [18]
• Return precautions: Fever, worsening abdominal pain, jaundice, nausea/vomiting, inability to tolerate PO, signs of wound infection
• Expected course: If treated early, rapid clinical improvement expected; delayed diagnosis carries risk of gangrenous cholecystitis, perforation, and multiorgan failure [5][8]
• Pearl: Unlike calculous cholecystitis, interval cholecystectomy may not be necessary in AAC patients treated with cholecystostomy if the precipitating condition resolves and stones remain absent [3][17][19]

1. Acute Cholecystitis: A Review. — Gallaher JR, Charles A. The Journal of the American Medical Association. 2022.

2. Acute Acalculous Cholecystitis: A Review. — Huffman JL, Schenker S. Clinical Gastroenterology and Hepatology : The Official Clinical Practice Journal of the American Gastroenterological Association. 2010.

3. Acute Acalculous Cholecystitis. — Barie PS, Eachempati SR. Current Gastroenterology Reports. 2003.

4. Acalculous Cholecystitis in the Critically Ill: Evolving Insights Into Diagnosis and Management. — Munir MM, Khan S, Huerta S. Current Opinion in Critical Care. 2026.

5. Acute Acalculous Cholecystitis in Hospitalized Patients in Intensive Care Unit: Study of 5 Cases. — Mossaab G, Ben Khlifa M, Karim N, et al. Heliyon. 2022.

6. Is Conservative Management a Safe Approach for Patients With Acute Acalculous Cholecystitis Presenting With an Acute Abdomen?. — Chang C, Wang Y, Shi W, et al. Medicine. 2023.

7. Acute Acalculous Cholecystitis in Children. — Poddighe D, Sazonov V. World Journal of Gastroenterology. 2018.

8. Recent Advances in Management of Acalculous Cholecystitis. — Balmadrid B. F1000Research. 2018.

9. Risk Factors and Therapeutic Outcomes of Acute Acalculous Cholecystitis. — Gu MG, Kim TN, Song J, et al. Digestion. 2014.

10. Current Status and Therapeutic Strategy of Acute Acalculous Cholecystitis: Japanese Nationwide Survey in the Era of the Tokyo Guidelines. — Morikawa T, Akada M, Shimizu K, et al. Journal of Hepato-Biliary-Pancreatic Sciences. 2024.

11. Clinical Update on Acute Cholecystitis and Biliary Pancreatitis: Between Certainties and Grey Areas. — Fugazzola P, Podda M, Tian BW, et al. EClinicalMedicine. 2024.

12. Biliary Tract Infections: A Guide to Drug Treatment. — Westphal JF, Brogard JM. Drugs. 1999.

13. Guidelines for the Appropriate Use of Bedside General and Cardiac Ultrasonography in the Evaluation of Critically Ill Patients-Part I: General Ultrasonography. — Frankel HL, Kirkpatrick AW, Elbarbary M, et al. Critical Care Medicine. 2015.

14. Clinical Outcomes of Percutaneous Cholecystostomy in Patients With Acute Cholecystitis Classified According to the Tokyo Guidelines, 2018: A Single-Center, Retrospective, Observational Study. — Kahraman YS, Yildiz YA, Taşkent İ, Gün F, Şentürk A. C Medicine. 2026.

15. Indications for and Optimal Management of Percutaneous Cholecystectomy Drainage. — Sadaka AH, Tseng JF, Itani KMF. JAMA Surgery. 2025.

16. Advances in the Study of Acute Acalculous Cholecystitis: A Comprehensive Review. — Fu Y, Pang L, Dai W, Wu S, Kong J. Digestive Diseases. 2021.

17. Acalculous Cholecystitis: Is an Elective Interval Cholecystectomy Necessary. — Abbas SH, Ghazanfar MA, Gordon-Weeks AN, et al. Digestive Surgery. 2017.

18. Long-Term Outcomes of Acute Acalculous Cholecystitis Treated by Non-Surgical Management. — Kim SB, Gu MG, Kim KH, Kim TN. Medicine. 2020.

19. Outcomes Following Percutaneous Cholecystostomy Tube Placement for Acalculous Versus Calculous Cholecystitis. — Chen SY, Huang R, Kallini J, et al. World Journal of Surgery. 2022.