Question 1

Pathophysiology                                                                                                               (2 marks)

Acalculous cholecystitis is caused by gallbladder stasis from hypomotility that leads to increased intraluminal pressures in the gallbladder wall, resulting in ischemia, inflammation, and potential necrosis. Stasis can lead to bacterial colonisation and progress to infection.

Note: It was important to appreciate that hypomotility is the cause of stasis in this case as opposed to obstruction in the case of calculous cholecystitis

Diagnosis:                                                                                                               (4 marks)

Often associated with severe critical illness, trauma or burns, period of “shock” state e.g. post-cardiac arrest, prolonged fasting/on TPN.

History and physical examination generally unreliable – may have abdominal signs.

Features of systemic inflammation, including fever, raised WCC, septic shock, general deterioration during critical illness, but these are non-specific.

May be elevation of LFT’s but again non-specific.

Diagnosis usually based on consideration of possibility when investigating fever or shock in critically ill patient.

Radiology is mainstay of diagnosis

Ultrasonography is most reliable and convenient method- Increased GB wall thickness is primary diagnostic criteria (>3.5mm) Other signs include oedema, peri-cholecystic fluid, intramural gas.

Other imaging modalities:

CT scan- sensitive, not very specific

Cholescintigraphy (HIDA-CCK scan- measures ejection fraction of the GB (<35% abnormal) in response to CCK- time consuming and requires transport of critically ill patient )

Management:                                                                                                               (4 marks)

1. General supportive care (e.g. IV fluids; NBM; Pain control; Antiemetics)
2. Antibiotics (similar to peritonitis regimes)

Either single agent regimen; Piperacillin/Tazobactam or Meropenem Or combination regimen; Cefepime or Ceftazidime plus metronidazole

(Note: any suitable regime acceptable). Duration depends on achievement of source control

3. Gall bladder drainage- indicated in the setting of deterioration/shock despite antibiotics other causes ruled out.
   1. Percutaneous cholecystosomy (preferred technique, can be performed at the bedside)
   2. Open or laparoscopic cholecystectomy
   3. Transpapillary drainage through ERCP (not preferred method), or more recently endoscopic placement of covered metal stent

Examiners Comments:

Very few candidates had any idea about hypomotility in the pathophysiology of the disease. Knowledge gaps existed about pathophysiology, precise USS findings and role of cholecystostomy.

Discussion

Historical risk factors

• Strongly associated factors
  • Trauma with massive transfusion
  • Any recent surgery
  • Burns
  • Sepsis
  • TPN
  • Prolonged fasting
  • Critical illness in general
• Weakly associated factors
  • ERCP
  • Long hospital stay
  • Immunosuppression
  • Vasculitis
  • CBD obstruction
  • Obesity, diabetes, hypertension

Clinical manifestations:

• RUQ pain
• High bilirubin
• Cholestatic pattern of LFT elevation
• Fever
• Bacteraemia
• Sympathetic right sided pleural effusion
• Haemodynamic instability

Diagnostic investigations

• Abdominal ultrasound
• Abdominal CT
• Expected radiological findings:
  • Thickened gall bladder wall (over 3.5-4mm)
  • Pericholecystic fluid
  • Intramural gas
  • Echogenic or hyperdense bile sludge
  • Sloughed mucosa
  • Gall bladder distension
• HIDA
• Blood cultures

Management

Options for Management of Acalculous Cholecystitis

Option	Advantages	Disadvantages
Conservative (antibiotics)	Few complications May be the only option for high risk patients. In a mixed (calculous and acalculous) group, 87% of conservatively managed patients recovered completely. Patients with reasonably normal gall bladder function (over 40% GBEF) only need conservative management. There is still an option to progress to one of the other treatment options.	May delay definitive treatment The gallbladder may become necrotic and rupture, causing peritonitis Patients with a severely infected gall bladder will continue to get worse, as source control has not been achieved.
Percutaneous cholecystostomy	Fewer complications than open cholecystectomy Can serve as the definitive management option in 80% of cases Safe with ultrasound or CT guidance	No difference in mortality and morbidity when compared to laparoscopic cholecystectomy (but this was a population of patients who were not critically ill) Risk of drain dislodgement
Laparoscopic cholecystectomy	Fewer complications than open cholecystectomy A definitive management option	Not an option in some patients, particularly morbidly obese patients and those with severe respiratory failure Requires a surgeon familiar with the approach May end up converting to open anyway, losing all benefits of the laparoscopic approach.
Open cholecystectomy	A definitive management option. Allows for a thorough washout. Accomodates weird anatomy and allows earlier maagement of surgical complications. May be the only option for those with a gangrenous or perforated gall bladder.	Significant morbidity post operatively in the critically ill population (mortality may be up to 19%)