Empyema of the gallbladder is the most severe form of acute cholecystitis. Empyema of the gallbladder is usually the result of a progression of acute cholecystitis in a background of bile stasis and cystic duct obstruction. This is a surgical emergency which requires prompt treatment with antibiotics and urgent aspiration/removal of the gallbladder to reduce the risk of septic shock. 
Frequently empyema of the gallbladder is associated with calculus cholecystitis where there is an obstructed cystic duct and stasis of bile. The stagnant bile in the gallbladder has superinfection with microorganisms that lead to suppuration in an acutely inflamed gallbladder. Hence the gallbladder lumen becomes filled with exudative material and very often frank pus. Rarely empyema of the gallbladder may present in association with common bile duct stones or carcinoma of the gallbladder. Empyema can also occur in calculus cholecystitis.
Empyema of the gallbladder is estimated to occur in 5 % to 15% of cases diagnosed to have acute cholecystitis. It is noted to be the more morbid condition when occurring in, the older age group. There is the higher preponderance of males who develop this disease. Patients with an increased risk of acute cholecystitis such as those with associated diabetes, immunosuppressant therapy, or hemoglobinopathies have a higher chance of developing empyema of the gallbladder. Mortality is rare except in patients with advanced age, compromised immunity or significant comorbidities. The incidence of postoperative complications regardless of the surgical approach is estimated to be 10% to 20%.
The stagnant bile due to cystic duct obstruction in the background of gallstone disease can become infected. Severe infection is caused commonly by pathogenic Escherichia coli, Klebsiella, Streptococcus faecalis, and anaerobes such as Bacteroids and Clostridia. Pus formation follows this infection, tightly filling the lumen of the gallbladder. In a tense and edematous gallbladder, necrosis of the wall and perforation may ensue if drainage or removal of the gallbladder is not performed promptly. If not treated rapidly, patients can develop generalized sepsis or gangrene of the gallbladder resulting in perforation of the gallbladder. Rarely a fistula between the gallbladder and duodenum can occur as a sequela of inadequately treated empyema of the gallbladder. Untreated cases develop symptoms of localized sepsis due to micro perforation or generalized sepsis due to macro perforation.
Pathological examination of the emphysematous gallbladder show marked edema and inflammation. The wall of the gallbladder may be covered externally by a fibrinous exudate. There is obvious pus which can be seen in the lumen of the gallbladder which at times appears creamy. On culture, this pus may not always grow organisms if the patient has been on antibiotic therapy. Microscopic examination of the mucosa can reveal ulceration and evidence of inflammation. There may be associated mucosal hemorrhage.
Patients with empyema of the gallbladder have symptoms similar to acute cholecystitis. Tenderness in the right upper quadrant and a positive Murphy's sign are the most common and predominant presenting symptoms. As the pathology progresses, there may be a palpable gallbladder detected which is acutely tender even on light palpation. With the worsening of the disease, high fever, chills, rigors, and signs of systemic sepsis follows. Patients who are on immunosuppressants or suffer from associated diabetes may have a more prolonged course with few associated typical signs and symptoms as described above.
In patients present with an initial stage of empyema, symptoms, physical signs and investigations may be unremarkable to distinguish from an acute cholecystitis. Frequently the patient has a raised white cell count on laboratory evaluation indicating an underlying infective cause. An ultrasound which is the most commonly used radiological investigation in gallbladder disease is not diagnostic can raise the suspicion of an empyema when there is very edematous gallbladder, or there are echogenic contents in the gallbladder associated with gallstones. A CT scan can be helpful when ultrasonogram is not contributory. A CT scan may reveal an enlarged or distended gallbladder with edematous walls and at times pericholecystic collection. When the diagnosis is more difficult an MRI can be of help. A heavily T2 weighted sequence on MRI can help in distinguishing pus from sludge.An MRI may also show a fluid level with a layering of purulent bile. An increasing white blood count with a shift to the left in a patient with acute cholecystitis is suggestive of adverse changes. The other relevant investigations are liver enzyme levels as well as PT (prothrombin time) and aPTT (activated partial thromboplastin time). Radiological findings alone may be insufficient for an accurate diagnosis of empyema of the gallbladder. A combination of clinical, radiological, and laboratory findings are crucial to arrive at a correct final diagnosis of empyema of the gallbladder.
Prompt parenteral antibiotic therapy with urgent removal or drainage of the gallbladder should be the goal to prevent increased morbidity and the rare possibility of mortality. Although the conventional practice is to perform an open cholecystectomy, it is possible to achieve a laparoscopic removal of the gallbladder by experienced surgeons. Surgeons who undertake laparoscopic approach should have a low threshold to convert to open procedure when encountered with technical difficulties. The conversion rate from laparoscopic to open cholecystectomy is higher in empyema of the gallbladder than that in uncomplicated acute cholecystitis. The higher rate of conversion is attributed to reduced visualization or distortion of the anatomical structures in the Calot's triangle as well as increased bleeding due to inflamed friable tissue. An initial decompression of the distended gallbladder either under the radiological guidance or intraoperative laparoscopically guided, facilitates the more straightforward dissection of the gallbladder. Postoperative complication rates irrespective of approach either laparoscopic or open is higher than for cholecystitis for gallstone disease. Postoperative complications which include wound infection, bleeding, cystic duct stump leak, and common bile duct injury, subhepatic abscess, have all been reported. A subtotal cholecystectomy is rarely is performed when the surgeon encounters pericholecystic inflammation that makes a safe dissection of the Calot's triangle impossible. In the elderly patients or those who are too ill to undergo surgery due to associated comorbidity, a percutaneous or transhepatic radiologically guided drainage is a temporizing procedure. This initial drainage procedure often leads to a dramatic improvement in the condition of the patient which then permits an elective cholecystectomy when the patient's condition improves.
Following surgery and removal of the gallbladder, IV antibiotics are required until the fever subsides and the WBC returns to normal. Most patients are discharged home on antibiotics for 1 week.
Empyema of the gallbladder may present with symptoms indistinguishable from acute cholecystitis. A high index of suspicion, as well as a combination of clinical, radiological, and laboratory parameters, helps in early diagnosis. Early and prompt surgical intervention in the form of cholecystectomy if not feasible, cholecystostomy prevents high morbidity and rare mortality.
Empyema of the gallbladder is a serious disorder that requires prompt diagnosis and treatment. The infection can quickly become systemic and cause multiple organ failure. Most patients require aggressive hydration, IV antibiotics and surgery. Because the disorder is associated with serious complications during surgery, an interprofessional team approach is recommended. Besides the surgeon, the radiologist may be required to drain any residual collections. The patient may be monitored in the ICU where the nurse is responsible for monitoring the patient closely for any respiratory distress and renal dysfunction. These patients are also prone to wound infections, DVT, and pneumonia- hence vigilance is necessary.
The pharmacist should manage the medications and ensure that polypharmacy does not occur, which can exacerbate the already compromised patient. Finally, there is a growing body of evidence indicating that after optimal hydration of the patient, the surgeon should remove the gallbladder within 48-72 hours. (Level V)
When the condition is diagnosed and treated early, the prognosis is excellent. However, in patients who are immunocompromised, old or those with diabetes, empyema of the gallbladder can be unpredictable and cause severe sepsis. Further, the rate of conversion of a laparoscopic procedure into an open procedure is also higher in gallbladder empyema. (Level III)