Acute Cholecystitis

Detailed Overview

Approximately 90% of cases are calculous, meaning they are caused by a gallstone impacting the gallbladder neck or cystic duct. The remaining 10% are acalculous, typically occurring in critically ill patients due to gallbladder stasis and ischemia. The continuous obstruction leads to an increase in intraluminal pressure, compromising venous return and potentially causing necrosis and perforation if left untreated. Early surgical intervention is standard to prevent complications such as gangrenous cholecystitis, gallbladder perforation, or cholecystoenteric fistulas.

Epidemiology & Demographics

Occurs in approximately 10-20% of patients with symptomatic gallstones. More common in women than men (ratio 2:1) up to age 50, after which the incidence becomes more equal. Peak incidence is in the 5th and 6th decades of life.

Etiological Mechanism

Primary cause is cholelithiasis (gallstones) obstructing the cystic duct (90%). Secondary causes (acalculous) include prolonged fasting, total parenteral nutrition, critical illness (trauma, burns, sepsis), and infections (e.g., Salmonella, CMV in immunocompromised).

Primary Causes

Cholelithiasis (Gallstones)

Biliary sludge

Gallbladder dysmotility/stasis

• Female sex: Increased estrogen levels increase cholesterol saturation in bile.
• Obesity: Increases hepatic cholesterol secretion and reduces bile acid pool size.
• Age > 40: Increased risk of gallstone formation with age.

A gallstone becomes impacted in the cystic duct. Biliary stasis leads to concentrated bile, which is toxic to the gallbladder mucosa (chemical cystitis). Increased intraluminal pressure compromises venous and lymphatic drainage, leading to ischemia. Prostaglandin release exacerbates inflammation. Secondary bacterial colonization (typically E. coli, Klebsiella, Enterococcus) occurs in 50-75% of cases. Without treatment, full-thickness wall ischemia leads to gangrene or perforation.

Characteristic Clinical Presentation

• Right Upper Quadrant Pain: Severe, steady pain lasting > 6 hours, often radiating to the right shoulder or back (scapula).
• Nausea and Vomiting: Commonly accompanies the pain, often triggered by fatty meals.
• Fever: Low-grade fever (e.g., 38.0 - 38.5°C) due to systemic inflammation.

Physical Examination Signs

• Murphy's Sign
• RUQ Tenderness/Guarding

• Gangrenous Cholecystitis: Ischemia and necrosis of the gallbladder wall, increasing perforation risk.
• Gallbladder Perforation: Can lead to localized abscess or generalized peritonitis.

Diagnostic Criteria & Guidelines

Tokyo Guidelines (2018): Suspected diagnosis requires one local sign of inflammation (Murphy's sign, RUQ pain) AND one systemic sign of inflammation (Fever, CRP > 3 mg/dL, WBC > 10,000/mcL). Definite diagnosis requires both plus imaging findings of acute cholecystitis.

Differential Diagnosis

• Acute Pancreatitis
• Peptic Ulcer Disease
• Acute Hepatitis

Laboratory Tests & Biomarkers

• WBC Count: Leukocytosis (typically 10,000 - 15,000/mcL) with a left shift.
• C-Reactive Protein (CRP): Elevated, often > 3 mg/dL.
• Liver Function Tests: Mild elevation in AST, ALT, and Alkaline Phosphatase. Significant hyperbilirubinemia (>2 mg/dL) suggests choledocholithiasis.

Imaging Modalities & Findings

• Abdominal Ultrasound: Gallbladder wall thickening (> 4 mm), pericholecystic fluid, and sonographic Murphy's sign.
• HIDA Scan: Non-visualization of the gallbladder after 4 hours implies cystic duct obstruction.

• Grade I (Mild)
  Acute cholecystitis without organ dysfunction or severe local inflammation.
• Grade II (Moderate)
  Associated with elevated WBC count (>18,000/mm3), palpable tender mass, duration >72h, or marked local inflammation.
• Grade III (Severe)
  Associated with cardiovascular, neurological, respiratory, renal, hepatic, or hematological dysfunction.

Second-Line & Adjunctive Therapy

Percutaneous cholecystostomy tube placement under ultrasound or CT guidance to decompress the gallbladder for very high-risk surgical candidates.

Surgical & Procedural Management

Laparoscopic cholecystectomy is the definitive treatment. Open cholecystectomy if severe inflammation obscures anatomy.

Recommended Lifestyle Changes

• Gradual weight loss (0.5 to 1 kg per week) if overweight.
• Low-fat diet post-operatively to manage potential bile diarrhea.

Patient Counseling & Advice

Explain that surgery cures the condition. Discuss the possibility of post-cholecystectomy syndrome (mild persistent symptoms or diarrhea in 5-10% of patients).

Follow-Up & Monitoring Schedule

Post-operative follow-up at 1-2 weeks for wound check and review of surgical pathology.

Preventive Strategies

Prophylactic cholecystectomy for asymptomatic gallstones is generally NOT recommended.

Excellent with timely surgical intervention. Mortality rate for uncomplicated laparoscopic cholecystectomy is < 0.5%.