Acute Cholecystitis

Slide 1 · Acute Cholecystitis

Pathogenesis • morphology • clinical correlation

Calculous and acalculous patterns

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives: Explain, recognize, distinguish

Explain how cystic outflow obstruction initiates calculous inflammation.

Describe the ischemic and stasis-related mechanisms of acalculous disease.

Recognize gross, microscopic and clinical hallmarks of acute cholecystitis.

Distinguish dangerous complications and the chronic counterpart.

Slide 3 · The gallbladder stores and concentrates bile

Physiologic context

Liver secretion may reach approximately 1 L of bile daily.

Between meals, the gallbladder stores and concentrates bile.

Pathologic relevance

Adult gallbladder capacity is approximately 50 mL.

Stored bile is exposed to abrupt outflow obstruction and pressure changes.

Slide 4 · Cholecystitis is a clinicopathologic spectrum

Acute

Abrupt gallbladder inflammation.

Frequently follows an impacted gallstone.

Chronic

Repeated or sustained wall inflammation.

May occur without known acute attacks.

Acute on chronic

Acute inflammation may supervene on chronic gallbladder disease.

History and morphology may overlap.

Slide 5 · Stone obstruction explains most acute attacks

Distribution of acute attacks

90%

10%

Stone obstruction / calculous

Acalculous

The groups describe triggering mechanisms, not different histologic appearances.

Slide 6 · The cystic duct and neck are critical sites

Stone at outlet

Gallbladder

Relevant anatomy

Gallbladder lumen stores and concentrates bile.

Neck continues into the cystic duct.

Outflow obstruction initiates most acute attacks.

Slide 7 · Biliary pain is not equivalent to acute inflammation

Symptomatic stones

Gallbladder contraction pushes a calculus against the outlet.

Pressure and pain may occur without established cholecystitis.

Acute cholecystitis

Progressive right upper quadrant or epigastric pain.

Pain characteristically persists beyond 6 hours.

Slide 8 · Stone formation sets the upstream conditions

Cholesterol supersaturation

Crystal nucleation

Mucus trapping

Macroscopic calculus

Hypomotility of the gallbladder further favors cholesterol stone formation.

Slide 9 · Calculous cholecystitis is a major gallstone complication

It is described as the principal complication of gallstones.

It is the commonest reason for emergency cholecystectomy in the source.

Diabetes with symptomatic gallstones is an important clinical setting.

Slide 10 · Calculous injury begins with outflow obstruction

Impacted calculus

Impaired gallbladder emptying

Luminal distention

Chemical and vascular injury

This is initially an inflammatory response to the obstructed, distended organ.

Slide 11 · Phospholipases convert lecithins into lysolecithins

Luminal lecithins

Mucosal phospholipase action

Toxic lysolecithins

Chemical mucosal irritation

The toxin-producing reaction is part of the stated chemical-injury mechanism.

Slide 12 · A protective mucus layer normally limits bile injury

Intact barrier

Glycoprotein mucus separates epithelial cells from concentrated bile.

The mucosal surface is normally protected.

Barrier disruption

Acute inflammation damages the protective mucus layer.

The epithelium becomes directly exposed to bile salts.

Slide 13 · Bile salts become harmful when the barrier is lost

1

Glycoprotein mucosal protection is disrupted.

2

Bile salts come into direct contact with epithelium.

3

Detergent action worsens epithelial injury.

4

Chemical injury reinforces local inflammation.

Slide 14 · Prostaglandins contribute to mural inflammation

Distended gallbladder tissue releases inflammatory prostaglandins.

Their activity contributes to mucosal and mural inflammation.

The response is not explained solely by bacterial contamination.

Slide 15 · Distention increases intraluminal pressure

Cystic duct obstruction

Failure of drainage

Luminal distention

Raised intraluminal pressure

Progressive pressure increases the threat to gallbladder-wall perfusion.

Slide 16 · Pressure-related vascular compromise injures mucosa

Wall distention

Increased pressure

Compromised mucosal blood flow

Worsening wall injury

The mechanical and chemical pathways are concurrent rather than mutually exclusive.

Slide 17 · Calculous pathogenesis is multifactorial

Chemical

Lysolecithins are injurious.

Bile salts act directly after mucus loss.

Inflammatory

Prostaglandins enhance mucosal and mural reactions.

Irritation initially need not involve bacteria.

Vascular

Distention elevates pressure.

Mucosal blood flow becomes compromised.

Slide 18 · Initial injury may be sterile

Early phase

Obstruction causes chemical irritation and ischemic stress.

A bacterial cause is not required at onset.

Subsequent course

Bacterial infection may be superimposed.

Superinfection can intensify the inflammatory process.

Slide 19 · Superinfection changes the inflammatory burden

1

Initial chemically mediated inflammation develops.

2

Infection may become superimposed later.

3

Suppurative exudate may accumulate in the lumen.

4

Sepsis becomes a possible complication.

Slide 20 · Calculous disease: The complete causal chain

Outlet calculus

Distention

Chemical barrier injury

Vascular compromise

Inflammation

Secondary bacteria may aggravate this chain, but are not mandatory to initiate it.

Slide 21 · Acalculous cholecystitis occurs without stones

Approximately 10% of acute attacks occur without gallstones.

Disease arises most often in patients severely ill for another reason.

The dominant proposed mechanism is ischemic gallbladder injury.

Slide 22 · Acalculous cholecystitis is fundamentally ischemic

Systemic stress

Reduced wall perfusion

Ischemic tissue injury

Acute inflammation

This summarizes the proposed predominant mechanism, not a universal exclusive pathway.

Slide 23 · The cystic artery has limited collateral protection

Anatomic property

The cystic artery functions as an end artery.

The source describes no collateral circulation.

Clinical implication

Reduced perfusion can rapidly compromise the wall.

Systemic hypotension therefore increases vulnerability.

Slide 24 · Sepsis and hypotension undermine wall perfusion

Sepsis / hypotension

Reduced arterial delivery

Gallbladder ischemia

Wall inflammation

Sepsis with hypotension and multiorgan dysfunction is a source-listed risk context.

Slide 25 · Mural edema can worsen ischemic compromise

Wall inflammation

Mural edema

Further blood-flow compromise

Amplified injury

The sequence is a simplified causal loop: Edema and inflammation can aggravate vascular compromise.

Slide 26 · Stasis provides a second acalculous mechanism

Poor emptying

Biliary sludge

Impaired cystic outflow

Gallbladder injury

Sludge can obstruct the cystic duct even in the absence of a macroscopic stone.

Slide 27 · Acalculous obstruction may involve three materials

Microcrystals

Cholesterol crystals accumulate as sludge.

The material is not a typical macroscopic gallstone.

Viscous bile

Concentrated, thick bile contributes to stasis.

Impaired drainage sustains retention.

Mucus

Mucus joins the stagnant luminal contents.

Outflow compromise may occur without stones.

Slide 28 · Acalculous injury is a reinforcing process

1

Critical illness promotes ischemia or biliary stasis.

2

Stasis and sludge impede emptying.

3

Inflammation and edema further impair perfusion.

4

The acutely inflamed wall may become necrotic.

Slide 29 · Sepsis with organ failure is a major risk setting

Sepsis and hypotension are recognized risk factors.

Multisystem organ failure may coexist.

Gallbladder symptoms may be masked by the primary illness.

Slide 30 · Trauma and extensive burns increase vulnerability

Major trauma and burns are established risk contexts.

Systemic physiologic stress can coexist with vascular compromise.

An acalculous attack may be overlooked during intensive care.

Slide 31 · Immunosuppression and diabetes matter

Immunosuppression

Listed as a risk factor for acute acalculous inflammation.

Overlapping illness may obscure manifestations.

Diabetes mellitus

A risk factor for acalculous episodes.

Also highlighted in symptomatic calculous disease.

Slide 32 · Rare primary infections can be acalculous

Some episodes are caused by primary bacterial infection.

The source names Salmonella Typhi and staphylococci as examples.

These are unusual mechanisms, not the general explanation for acalculous attacks.

Slide 33 · More indolent acalculous disease has other contexts

Vascular causes

Systemic vasculitis.

Severe atherosclerotic ischemic disease in older patients.

Infectious / biliary contexts

AIDS-associated disease, often linked in the source to Cryptosporidium.

Ascending biliary tract infection.

Slide 34 · Calculous versus acalculous: Different triggers

Calculous

Obstructing stone in neck or cystic duct.

Toxic bile exposure and pressure-induced vascular compromise.

Acute pain often clinically conspicuous.

Acalculous

Absence of a gallstone.

Ischemia and biliary stasis are prominent.

Often develops amid severe illness.

Slide 35 · Acute cholecystitis enlarges and distends the organ

The gallbladder is usually enlarged and tense.

The serosal surface may appear unusually congested or discolored.

Macroscopic appearance depends on the severity of injury.

Slide 36 · Serosal discoloration reflects hemorrhagic injury

Reported colors

Bright red or blotchy violaceous regions.

Severe injury may yield a green-black appearance.

Structural explanation

Subserosal hemorrhages contribute to discoloration.

Progression to green-black necrosis marks gangrenous disease.

Slide 37 · The serosa may develop fibrinous exudate

Mural inflammation

Serosal reaction

Fibrinous coating

Fibrinopurulence if severe

Exudate is a pathologic surface finding, distinct from luminal pus.

Slide 38 · Inflamed gallbladder contents become turbid

Bile may appear cloudy or turbid rather than clear.

Fibrin, pus and hemorrhage can mix with luminal bile.

Additional stones are common in calculous cases.

Slide 39 · A calculus may remain impacted at the outlet

Location

Gallbladder neck.

Cystic duct.

Meaning

Persistent obstruction explains luminal distention.

The finding distinguishes the calculous form from acalculous morphology.

Slide 40 · Empyema means a lumen dominated by pus

Gallbladder empyema = virtually pure pus within the lumen

A suppurative complication of acute inflammation.

Not synonymous with uncomplicated biliary stasis.

Slide 41 · Mild acute disease shows edema and hyperemia

Gross findings

Thickening of the gallbladder wall.

Edematous, hyperemic appearance.

Microscopic correlates

Interstitial edema and vascular congestion.

Early erosion of the mucosal lining.

Slide 42 · Gangrenous cholecystitis is necrotizing injury

Mild

Edematous, hyperemic wall

Severe

Green-black wall necrosis

Complicated

Potential perforation

Schematic progression: Actual pathology varies by severity and case.

Slide 43 · Perforation follows destructive wall injury

Mural necrosis

Loss of wall integrity

Perforation

Localized or diffuse contamination

Complications include local abscess or diffuse peritonitis.

Slide 44 · Gas-forming infection may cause emphysematous disease

Etiologic organisms cited

Clostridia.

Coliform bacteria.

Pathologic consequence

Organisms can generate gas in the inflamed gallbladder.

This is a severe infectious variant, not typical early sterile injury.

Slide 45 · Early histology shows vascular and epithelial injury

1

Vascular congestion in the gallbladder wall.

2

Interstitial mural edema.

3

Erosion of the mucosal surface.

4

Variable superimposed suppurative inflammation.

Slide 46 · Early neutrophils may be less prominent than expected

Typically sparse neutrophils in early acute disease.

A striking neutrophilic infiltrate may appear with superimposed infection.

Early morphological interpretation requires the vascular and epithelial context.

Slide 47 · Stone presence is the main morphological discriminator

Shared acute findings

Edema, congestion and erosion.

Serosal exudation and possible necrosis.

Turbid luminal contents if advanced.

Specific distinction

An obstructing gallstone is identified in calculous disease.

Acalculous attacks lack such a stone; Otherwise the lesions overlap.

Slide 48 · Pain usually persists beyond six hours

Pain becomes progressive in the right upper quadrant or epigastrium.

Persistence beyond 6 hours is characteristic in the source.

Prior gallbladder-related painful episodes are common but not obligatory.

Slide 49 · Fever and gastrointestinal symptoms often accompany pain

Constitutional

Mild fever.

Sweating and tachycardia.

Appetite

Anorexia may occur.

An attack can begin suddenly.

Gastrointestinal

Nausea.

Vomiting.

Slide 50 · Jaundice suggests additional ductal obstruction

Typical acute cholecystitis

Most affected patients are not jaundiced.

Inflammation often remains centered on the gallbladder.

Concerning additional finding

Hyperbilirubinemia raises suspicion of common bile duct obstruction.

Assess the biliary tree beyond the cystic duct.

Slide 51 · Laboratory changes provide supportive clues

Mild to moderate leukocytosis may accompany acute disease.

Serum alkaline phosphatase can be modestly elevated.

Neither finding alone identifies the triggering mechanism.

Slide 52 · Clinical severity ranges from mild to urgent

Relatively mild course

Some attacks resolve without intervention.

Symptoms may decrease over the following days.

Progressive disease

A substantial minority worsen instead of resolving.

Severe progression can demand immediate surgical attention.

Slide 53 · Symptom resolution does not eliminate recurrence

Acute symptomatic episode

Clinical improvement

Gallstones persist

New episode may recur

Recurrence is common when patients recover without surgery.

Slide 54 · Acalculous presentations can be clinically silent

Symptoms may evolve insidiously rather than abruptly.

Critical illness may obscure gallbladder-related complaints.

A higher proportion have no localizing gallbladder symptoms.

Slide 55 · Delayed recognition threatens the acalculous patient

Severe underlying illness

Subtle gallbladder symptoms

Delayed recognition

Gangrene / perforation

The source stresses the much higher complication rate in acalculous disease.

Slide 56 · Bacterial superinfection can spread beyond gallbladder

Acute cholecystitis

Bacterial superinfection

Cholangitis or sepsis

Systemic deterioration may accompany spread or superinfection.

Slide 57 · Perforation has localized and diffuse outcomes

Contained injury

Gallbladder perforation.

Local abscess formation.

Uncontained rupture

Spillage into the peritoneal cavity.

Diffuse peritonitis.

Slide 58 · Biliary-enteric fistula links gallbladder to bowel

Inflammatory fistula

Biliary–enteric connection

Air and bacteria enter bile ducts

Stone-related ileus possible

A gallstone may pass into bowel through a fistula and obstruct intestine.

Slide 59 · Acute gallbladder disease can destabilize other organs

Cardiopulmonary

Preexisting cardiac illness may worsen.

Pulmonary decompensation is possible.

Renal

Acute illness may worsen renal function.

Multiorgan dysfunction increases risk.

Hepatic

Liver disease may decompensate.

Sepsis and biliary obstruction add burden.

Slide 60 · Chronic cholecystitis supplies important context

Chronic disease can follow recurrent acute attacks.

It also develops without a documented history of acute attacks.

It is associated with cholelithiasis in more than 90% of cases.

Slide 61 · Chronic disease is not simply persistent acute edema

Acute-dominant pattern

Edema, congestion, mucosal erosions.

Fibrinous or fibrinopurulent exudate.

Chronic-dominant pattern

Fibrosis and mononuclear inflammation.

Wall thickening, adhesions and epithelial outpouchings.

Slide 62 · Acute and chronic cholecystitis: Contrast

Feature

Acute

Chronic

Pain

Progressive; >6 h typical

Recurrent steady RUQ/epigastric

Pathology

Edema / acute injury ± necrosis

Variable fibrosis and mononuclear cells

Outlet stone

Commonly obstructs neck/duct

Outflow obstruction not prerequisite

Systemic illness

Fever and leukocytosis possible

Less striking manifestations

Slide 63 · Case 1: Progressive pain with an impacted stone

ILLUSTRATIVE CLINICAL VIGNETTE

An adult has sustained right upper quadrant pain for over 6 hours.

Nausea and low-grade fever accompany the attack.

A stone is found lodged at the gallbladder neck.

What initiates inflammation, and is early bacterial infection required?

Slide 64 · Case 1: The first injury is chemical and vascular

Trigger

Cystic outlet stone prevents emptying.

Gallbladder distention impairs mucosal perfusion.

Mechanism

Lysolecithins and bile salts cause chemical injury.

Bacterial superinfection may occur subsequently.

Slide 65 · Case 2: An ICU patient without localizing pain

ILLUSTRATIVE CLINICAL VIGNETTE

A critically ill patient has sepsis, hypotension and organ failure.

No gallstone is identified.

Clinical findings referable to the gallbladder are minimal.

Which form is likely, and what complication must be anticipated?

Slide 66 · Case 2: Suspect ischemic acalculous injury

Reasoning

Acalculous attacks occur with severe systemic illness.

End-arterial circulation makes the wall ischemia-prone.

Urgency

The onset may be insidious and occult.

Gangrene and perforation are particularly concerning.

Slide 67 · Case 3: A dark gallbladder wall and pus

ILLUSTRATIVE CLINICAL VIGNETTE

An enlarged gallbladder appears green-black at surgery.

The lumen contains abundant purulent material.

The wall contains focal areas of perforation.

Identify the three pathological complications represented.

Slide 68 · Case 3: Identify the complications precisely

Gangrene

Green-black wall necrosis.

Severe tissue destruction.

Empyema

Virtually pure pus in the lumen.

Suppurative complication.

Perforation

Loss of wall integrity.

May form abscess or peritonitis.

Slide 69 · The two etiologic pathways converge on wall injury

Calculous: Obstructing stone

Pressure / chemical injury

Mural inflammation

Edema / necrosis / perforation

Acalculous disease reaches overlapping damage through ischemia and stasis rather than a large obstructing stone.

Slide 70 · Four diagnostic concepts to retain

Calculous attacks start with cystic outflow obstruction in most cases.

Acalculous disease preferentially affects severely ill patients and is ischemia-prone.

Gross and microscopic inflammation overlap; Stones distinguish the two etiologies.

Gangrene, empyema, perforation and systemic infection signal dangerous progression.

Slide 71 · Primary teaching reference

Robbins, Cotran & Kumar: Pathologic Basis of Disease

11th edition (2026).

Gallbladder — cholecystitis and related complications.