Cholecystitis

Cholecystitis – High‑Yield Study Guide for Medical Students

Cholecystitis is a core GI/surgical topic and a frequent cause of acute abdomen. Understanding its pathophysiology, presentation, diagnostic workup, and management is essential for exams and clinical practice.

Definition

Cholecystitis is inflammation of the gallbladder, most commonly due to persistent obstruction of the cystic duct by gallstones (calculous cholecystitis). A smaller proportion of cases occur without stones (acalculous cholecystitis), typically in critically ill patients.

• Acute calculous cholecystitis: acute gallbladder inflammation caused by gallstone obstruction of the cystic duct.
• Acalculous cholecystitis: gallbladder inflammation without stones, usually in severely ill or postoperative patients.
• Chronic cholecystitis: long-standing gallbladder inflammation, usually from repeated bouts of mild acute inflammation and gallstones leading to fibrosis and functional impairment.

Epidemiology

Cholecystitis is one of the most common indications for urgent abdominal surgery.

• Strongly associated with cholelithiasis; ~90–95% of acute cholecystitis is calculous.
• More common in females (especially reproductive age) due to estrogen-related changes in bile composition.
• Increased incidence with age, obesity, metabolic syndrome, and certain ethnic groups (e.g., Native Americans have higher gallstone prevalence).
• Acalculous cholecystitis accounts for ~5–10% of cases, but carries higher morbidity and mortality, particularly in ICU populations.

Pathophysiology

Calculous Cholecystitis

The key event is obstruction of the cystic duct by a gallstone or sludge, leading to gallbladder distension, inflammation, and potential infection.

• Cystic duct obstruction: A gallstone becomes impacted at the gallbladder neck or cystic duct, blocking bile outflow.
• Gallbladder distension: continued secretion of mucus and fluid causes increased intraluminal pressure and wall tension.
• Chemical inflammation: concentrated bile, lysolecithin, and prostaglandins damage the mucosa and recruit inflammatory mediators.
• Vascular compromise: increased pressure impairs venous and lymphatic drainage, leading to edema, ischemia, and possible necrosis.
• Bacterial involvement: secondary infection with enteric organisms (commonly E. coli, Klebsiella, Enterococcus, Clostridium) may superimpose, worsening inflammation and systemic response.

Acalculous Cholecystitis

Acalculous cholecystitis is driven by gallbladder stasis, ischemia, and infection, rather than stones.

• Occurs in severely ill patients (sepsis, trauma, major surgery, burns, prolonged fasting, TPN).
• Stasis due to hypomotility and fasting leads to sludge and concentration of bile.
• Hypoperfusion and microthrombi cause ischemic injury to the gallbladder wall.
• Bacterial translocation can lead to severe inflammation, gangrene, and perforation.

Chronic Cholecystitis

Chronic cholecystitis results from recurrent or longstanding gallbladder inflammation due to stones or functional obstruction.

• Repeated episodes of subclinical or mild acute cholecystitis → progressive fibrosis and thickening of the gallbladder wall.
• Associated with Rokitansky–Aschoff sinuses (outpouchings of mucosa through the muscular layer).
• Can progress to a porcelain gallbladder (calcification of the wall), which has an association with gallbladder carcinoma.

Risk Factors

Classically remembered for gallstone disease: the "4 F's" in calculous cholecystitis.

• Female
• Fat (obesity, metabolic syndrome)
• Fertile (pregnancy, multiparity; estrogen increases cholesterol saturation of bile)
• Forty (middle age)

Additional risk factors include:

• Rapid weight loss, bariatric surgery
• Hemolytic disorders (e.g., sickle cell disease → pigment stones)
• Diabetes mellitus
• Hyperlipidemia and high-calorie diets
• Prolonged fasting, TPN (particularly for acalculous cholecystitis)
• Critical illness, trauma, major surgery, vasculitis (for acalculous cholecystitis)

Clinical Presentation

Acute Calculous Cholecystitis

The classic presentation is constant right upper quadrant (RUQ) pain with systemic signs of inflammation.

• Pain characteristics:
  • Persistent, steady RUQ or epigastric pain lasting >4–6 hours (vs biliary colic which is episodic <4–6 hours).
  • Often begins after a fatty meal.
  • Radiation to the right scapula or shoulder (via phrenic nerve irritation).
• Associated symptoms:
  • Anorexia, nausea, and vomiting.
  • Low-grade fever and malaise.
  • Mild jaundice may be present but is not a dominant feature unless common bile duct obstruction is present.
• Physical exam:
  • RUQ tenderness and guarding.
  • Murphy sign: inspiratory arrest on deep palpation of the RUQ due to pain as the inflamed gallbladder contacts the examiner's hand. Highly suggestive of acute cholecystitis.
  • Possible palpable tender gallbladder in some patients.
  • Tachycardia, signs of systemic inflammatory response in more severe cases.

Acalculous Cholecystitis

Acalculous cholecystitis often presents atypically and may be subtle.

• Typically occurs in critically ill patients (ICU, ventilated), making history and exam difficult.
• May present with unexplained fever, leukocytosis, sepsis, or vague abdominal distension/pain.
• High index of suspicion is needed, especially in patients with risk factors and no clear source of sepsis.

Chronic Cholecystitis

• Recurrent episodes of biliary-type pain, often postprandial, particularly after fatty meals.
• Less intense and less systemic than acute cholecystitis.
• May present with dyspepsia, bloating, and intolerance to fatty foods.

Diagnosis

Diagnosis is based on clinical assessment supported by laboratory tests and imaging. Tokyo Guidelines are often used for standardized diagnosis and severity grading.

Laboratory Findings

• CBC: leukocytosis with left shift is common in acute cholecystitis.
• Liver function tests (LFTs):
  • Mild elevation in AST/ALT possible.
  • Alkaline phosphatase and GGT may be mildly elevated.
  • Significant elevation in bilirubin and cholestatic enzymes suggests possible choledocholithiasis or ascending cholangitis rather than isolated cholecystitis.
• CRP/ESR: often elevated, reflecting inflammation.
• Amylase/lipase: evaluated to exclude gallstone pancreatitis if epigastric pain or back radiation.

Imaging

Ultrasound (First-Line Imaging)

Abdominal ultrasound is the initial imaging modality of choice.

• Findings supporting acute cholecystitis:
  • Gallstones (or sludge) in the gallbladder.
  • Gallbladder wall thickening (>3 mm).
  • Pericholecystic fluid.
  • Enlarged, distended gallbladder.
  • Sonographic Murphy sign: maximal tenderness when the ultrasound probe compresses the gallbladder.
• Ultrasound is also useful for assessing bile ducts and excluding choledocholithiasis or other pathology.

HIDA Scan (Cholescintigraphy)

Hepatobiliary iminodiacetic acid (HIDA) scan is highly sensitive and specific when ultrasound is equivocal.

• In acute calculous cholecystitis, the gallbladder fails to visualize due to cystic duct obstruction.
• HIDA scan is particularly useful in early disease or in obese patients or those with technically difficult ultrasound.

CT and MRI

• CT abdomen may be used to evaluate complications (perforation, abscess, emphysematous cholecystitis) or if diagnosis remains uncertain.
• MRCP is reserved mainly for evaluating the biliary tree for choledocholithiasis or other biliary pathology.

Diagnostic Criteria (Simplified Clinical Approach)

In practice, diagnosis of acute cholecystitis is often made when the following are present:

• Local signs of inflammation: RUQ pain/tenderness, positive Murphy sign.
• Systemic signs of inflammation: fever, leukocytosis, elevated CRP.
• Imaging evidence: characteristic ultrasound or HIDA scan findings of gallbladder inflammation.

Management

Management differs for acute calculous, acalculous, and chronic cholecystitis but centers around supportive care, antibiotics, and definitive surgical management.

Initial Supportive Management

• NPO (nil per os): rest the gut and reduce gallbladder stimulation.
• IV fluids: maintain hemodynamic stability and correct volume deficits.
• Pain control: e.g., IV opioids titrated to effect.
• Antiemetics: symptomatic relief for nausea/vomiting.

Antibiotic Therapy

Empiric antibiotics are used in moderate to severe acute cholecystitis or when systemic signs are present, targeting gram-negative and anaerobic enteric organisms.

• Example regimens (local resistance patterns should guide choice):
  • Ceftriaxone + metronidazole
  • Or piperacillin–tazobactam monotherapy in higher-risk or severe cases
• Duration often 4–7 days depending on severity and source control.

Definitive Management – Cholecystectomy

Laparoscopic cholecystectomy is the definitive treatment for symptomatic cholecystitis due to gallstones.

• Acute calculous cholecystitis:
  • Early laparoscopic cholecystectomy (generally within 72 hours of presentation, often within same admission) is associated with better outcomes.
  • Open cholecystectomy is considered if anatomy is unclear, complications are present, or laparoscopic approach is unsafe.
• Chronic cholecystitis:
  • Elective laparoscopic cholecystectomy for recurrent biliary pain or complications.
  • Porcelain gallbladder typically warrants cholecystectomy due to carcinoma risk.

Management of Acalculous Cholecystitis

Acalculous cholecystitis often occurs in unstable patients who may not tolerate immediate surgery.

• Aggressive supportive care and broad-spectrum IV antibiotics.
• Percutaneous cholecystostomy (image-guided drainage of the gallbladder) in high-risk or critically ill patients as a temporizing or definitive measure.
• Interval cholecystectomy may be considered once the patient stabilizes, depending on risk and underlying condition.

Management of Complications

• Gallbladder perforation: emergency surgical intervention and drainage; may present with generalized peritonitis.
• Empyema of the gallbladder: pus in the gallbladder; urgent cholecystectomy or cholecystostomy plus antibiotics.
• Gangrenous cholecystitis: transmural necrosis; requires urgent operative management.
• Emphysematous cholecystitis: gas-forming organisms in gallbladder wall; more common in diabetics and requires urgent surgery and broad-spectrum antibiotics.
• Gallstone ileus: mechanical small bowel obstruction due to a large gallstone passing through a cholecystoenteric fistula; requires surgical removal of the stone and consideration of fistula repair.

Prevention and Long-Term Considerations

• Address modifiable risk factors: weight management, control of diabetes and dyslipidemia, gradual (not rapid) weight loss.
• Asymptomatic gallstones are generally not removed, except in select cases (e.g., sickle cell disease, porcelain gallbladder, large polyps).
• Post-cholecystectomy, most patients tolerate normal diets; a minority may have transient diarrhea or fat intolerance.

Key Clinical Pearls (High-Yield for Exams)

• Acute cholecystitis vs biliary colic: biliary colic is transient RUQ pain from temporary cystic duct obstruction without persistent inflammation; acute cholecystitis is sustained pain with inflammatory signs >4–6 hours.
• Murphy sign: inspiratory arrest with RUQ palpation is classic for acute cholecystitis and is often tested.
• Ultrasound: first-line imaging; look for gallstones, gallbladder wall thickening, pericholecystic fluid, and sonographic Murphy sign.
• HIDA scan: non-visualization of the gallbladder despite visualization of the bile ducts and duodenum is diagnostic when ultrasound is equivocal.
• Acalculous cholecystitis: think of this in critically ill or postoperative patients with unexplained sepsis or RUQ findings; mortality is higher and diagnosis is often delayed.
• Choledocholithiasis vs cholecystitis: prominent jaundice and markedly elevated cholestatic LFTs suggest common bile duct stones; consider ERCP in these cases.
• Cholangitis: Charcot triad (fever, jaundice, RUQ pain) and Reynolds pentad (triad + hypotension + altered mental status) represent biliary sepsis and require urgent biliary decompression, not just cholecystectomy.
• Porcelain gallbladder: calcified gallbladder wall on imaging is associated with increased risk of gallbladder carcinoma and typically indicates elective cholecystectomy.
• Diabetics and elderly: may present atypically or with more severe disease (e.g., emphysematous or gangrenous cholecystitis); maintain a low threshold for imaging and intervention.

Summary

Cholecystitis is most often a complication of gallstone disease, characterized by persistent RUQ pain with signs of inflammation and characteristic imaging findings. Early recognition, appropriate imaging, timely antibiotics when indicated, and definitive management with cholecystectomy (or cholecystostomy in select high-risk patients) are central to optimal outcomes. For exams, focus on differentiating biliary colic from acute cholecystitis, recognizing classic signs (Murphy sign, ultrasound findings), and knowing indications for surgical intervention and when to suspect complications or alternative diagnoses.