Acute Cholecystitis

1. Definition

Acute cholecystitis is acute inflammation of the gallbladder, usually due to cystic duct obstruction by gallstones, leading to distension, ischemia, and secondary infection.

  • 90–95% → Calculous cholecystitis
  • 5–10% → Acalculous cholecystitis (critically ill patients)

2. Anatomy Review 

  • Fundus → Body → Infundibulum → Neck
  • Hartmann’s pouch: stone impaction site
  • Cystic duct joins common hepatic duct
  • Calot’s triangle boundaries:
    • Cystic duct
    • Common hepatic duct
    • Inferior border of liver
      (Contains cystic artery)


3. Etiology & Risk Factors

A. Calculous (Most Common)

Gallstone obstructs cystic duct → bile stasis → inflammation

Risk factors (4 Fs classic):

Risk Factor

Pathophysiology

Female

Oestrogen ↑ cholesterol secretion into bile → supersaturation → cholesterol stone formation

Forty (Increasing age)

Age-related ↓ bile salt synthesis + ↑ cholesterol saturation → stone formation risk rises after 40

Fertile (Multiparity)

Repeated high oestrogen & progesterone exposure → ↑ cholesterol + ↓ gallbladder motility

Fat (Obesity)

↑ Hepatic cholesterol synthesis → cholesterol supersaturation of bile

Rapid weight loss

Mobilisation of cholesterol from adipose tissue → bile supersaturation + gallbladder hypomotility

Pregnancy

Progesterone → gallbladder hypomotility; Oestrogen → ↑ cholesterol secretion

OCP use

Oestrogen component ↑ cholesterol in bile → promotes cholesterol stones

Diabetes mellitus

Autonomic neuropathy → impaired gallbladder emptying; dyslipidaemia contributes

Hemolysis

↑ Unconjugated bilirubin load → pigment stone formation (calcium bilirubinate stones)



B. Acalculous Cholecystitis

Seen in:

  • ICU patients
  • Sepsis
  • Trauma
  • Burns
  • TPN
  • Post major surgery

Mechanism:

  • Bile stasis
  • Ischemia
  • Sludge
  • Secondary infection

 Higher mortality than calculous


4. Pathophysiology

  1. Stone blocks cystic duct
  2. Gallbladder distension
  3. Increased intraluminal pressure
  4. Ischemia
  5. Chemical inflammation (lysolecithin formation)
  6. Secondary bacterial infection (E. coli, Klebsiella, Enterococcus)

If untreated:

  • Gangrene
  • Perforation
  • Empyema


5. Clinical Features

Classical Presentation

  • RUQ pain (>6 hours)
  • Radiates to right shoulder/scapula
  • Fever
  • Nausea/vomiting

Murphy’s Sign

  • Arrest of inspiration on palpation of RUQ
  • Highly suggestive

 Differentials

  • Biliary colic
  • Acute cholangitis
  • Acute pancreatitis
  • Peptic ulcer perforation
  • Hepatitis
  • Right lower lobe pneumonia


6.Biliary Colic vs Cholecystitis

Feature

Biliary Colic

Acute Cholecystitis

Duration

<6 hours

>6 hours

Fever

No

Yes

WBC

Normal

Raised

Murphy’s sign

Negative

Positive

Inflammation

No

Yes


7. Investigations 

 Blood Tests

  • WBC ↑
  • CRP ↑
  • Mild LFT elevation
  • Bilirubin usually normal
  • ALP mild ↑

 Marked jaundice → think:

  • Choledocholithiasis
  • Mirizzi syndrome(Stone compresses common hepatic duct → obstructive jaundice)
  • Cholangitis


 Imaging

First-line: Ultrasound

Findings:

  • Gallstones
  • Wall thickening (>3 mm)
  • Pericholecystic fluid
  • Sonographic Murphy sign
  • Distended gallbladder

Sensitivity ~85–90%


 HIDA Scan (if US equivocal)

  • Non-visualization of gallbladder = diagnostic
  • Most sensitive test

 CT Scan

Useful for:

  • Complications
  • Perforation
  • Abscess
  • Gangrene


8. Severity Grading (Tokyo Guidelines)

Used clinically (important concept).

Grade I (Mild)

  • No organ dysfunction
  • Mild inflammation

Grade II (Moderate)

  • WBC >18,000
  • Palpable tender mass
  • 72 hours duration

Grade III (Severe)

  • Organ dysfunction (shock, renal failure, altered mental status)


9. Management 

A. Initial Management

  • NBM
  • IV fluids
  • Analgesia (NSAIDs preferred)
  • IV antibiotics

Antibiotics (Empirical)

Mild–moderate:

  • Co-amoxiclav
    OR
  • Ceftriaxone + metronidazole

Severe:

  • Piperacillin-tazobactam


B. Definitive Treatment

Early Laparoscopic Cholecystectomy (within 72 hours)

Gold standard

Advantages:

  • Shorter hospital stay
  • Fewer complications
  • Lower recurrence

Delayed surgery only if:

  • High surgical risk
  • Severe inflammation

C. Percutaneous Cholecystostomy

Indications:

  • Critically ill
  • Unfit for surgery
  • Grade III

Acts as bridge to surgery


10. Complications 

1. Empyema-Pus in gallbladder

2. Gangrenous cholecystitis-Ischemic necrosis

3. Perforation

→ Local abscess
→ Generalized peritonitis

4. Mirizzi Syndrome

5. Gallstone ileus-Stone enters bowel → small bowel obstruction