Acalculous cholecystitis: Clinical manifestations, diagnosis, and management

INTRODUCTION — Acalculous cholecystitis is an acute necroinflammatory disease of the gallbladder with a multifactorial pathogenesis. It accounts for approximately 10 percent of all cases of acute cholecystitis and is associated with high morbidity and mortality rates.

This topic will review the pathophysiology, diagnosis, and management of acalculous cholecystitis. Clinical issues related to acute calculous cholecystitis and chronic cholecystitis are discussed separately. (See "Acute calculous cholecystitis: Clinical features and diagnosis" and "Treatment of acute calculous cholecystitis".)

PATHOGENESIS — Acalculous cholecystitis results from gallbladder stasis and ischemia, which then cause a local inflammatory response in the gallbladder wall. The majority of patients with acalculous cholecystitis have multiple risk factors (table 1) [1-7]. In some cases, specific primary infections predispose to acalculous cholecystitis (table 2). As an example, acalculous cholecystitis occurring in patients with acquired immunodeficiency syndrome (AIDS) and other immunosuppressed patients may be due to opportunistic infections such as microsporidia, Cryptosporidium, or cytomegalovirus [8]. More often, however, these infections cause a cholangiopathy without cholecystitis. (See "AIDS cholangiopathy".)

Pathologically in patients with acalculous cholecystitis, endothelial injury, gallbladder ischemia, and stasis, lead to concentration of bile salts, gallbladder distension, and eventually necrosis of the gallbladder tissue. Once acalculous cholecystitis is established, secondary infection with enteric pathogens, including Escherichia coli, Enterococcus faecalis, Klebsiella spp, Pseudomonas spp, Proteus spp, and Bacteroides fragilis and related strains, is common [9]. Perforation occurs in severe cases [10,11]. (See 'Complications' below.)

EPIDEMIOLOGY — Acalculous cholecystitis is typically seen in patients who are hospitalized and critically ill, though it may also be seen in the outpatient setting in patients with risk factors for acalculous cholecystitis (table 1). Acalculous cholecystitis has been reported in 0.7 to 0.9 percent of patients following open abdominal aortic reconstruction, in 0.5 percent of patients following cardiac surgery, and in as many as 4 percent of patients who have undergone bone marrow transplantation [4,12-15]. There is a male preponderance among patients with acute acalculous cholecystitis ranging from 40 to 80 percent [12,16].

The incidence of acalculous cholecystitis in outpatients is not well defined. In one of the largest single center reports, 36 of 47 patients (77 percent) identified over a seven-year period developed symptoms at home without evidence of acute illness or trauma [17]. Significant vascular disease was observed in 72 percent of these patients. Although this suggests that the relative incidence in outpatients may be much higher than is generally recognized, some of these patients may have been misclassified as having acalculous cholecystitis since it is possible that gallstones or microcrystals had not been appreciated.

CLINICAL MANIFESTATIONS

Clinical presentation — The clinical presentation of acalculous cholecystitis varies based on the severity of illness and underlying predisposing conditions (table 1). In critically ill patients, the appearance of unexplained fever may be the only sign of acalculous cholecystitis. The physical examination may reveal a palpable right upper quadrant mass and rarely jaundice [17]. Jaundice typically results from sepsis-related cholestasis or partial biliary obstruction induced by inflammation extending into the common bile duct. However, it may also occur as a result of extrinsic compression of the common bile duct by a phlegmon (Mirizzi-type syndrome). Because the presentation may be insidious, patients may have sepsis, shock, and peritonitis at presentation due to complications including gallbladder necrosis, gangrene, or perforation. Patients with emphysematous cholecystitis may have crepitus of the right upper quadrant. (See 'Complications' below and "Mirizzi syndrome".)

In outpatients or in the critically ill who are able to provide a more detailed history, the presentation may be similar to that seen in calculous cholecystitis, with fever, severe right upper quadrant pain with tenderness to palpation, and a positive Murphy's sign (pain elicited during inspiration while palpating the right upper quadrant) [18,19]. (See "Acute calculous cholecystitis: Clinical features and diagnosis", section on 'Clinical manifestations'.)

Although a smoldering presentation characterized by recurrent biliary symptoms for months or years had previously been attributed to "chronic acalculous cholecystitis", the evaluation for concurrent gallstones or microcrystals has been limited [20,21]. These patients may in fact have had gallstone-related disease or functional gallbladder disorder. (See "Acute calculous cholecystitis: Clinical features and diagnosis" and "Overview of gallstone disease in adults" and "Functional gallbladder disorder in adults".)

Laboratory tests — Laboratory tests in patients with acalculous cholecystitis are nonspecific. Leukocytosis is present in 70 to 85 percent of patients [22]. Abnormal liver tests include conjugated hyperbilirubinemia and a mild increase in serum alkaline phosphatase and serum aminotransferases [17]. (See "Approach to the patient with abnormal liver biochemical and function tests".)

Complications — Similar to patients with acute calculous cholecystitis, complication of acalculous cholecystitis include emphysematous cholecystitis, gangrene, and perforation (image 1) [1,19]. Gallbladder gangrene develops in approximately 50 percent of patients with acalculous cholecystitis and can result in gallbladder perforation [23]. Emphysematous cholecystitis, in particular, puts patients at risk for perforation. Overall, perforation occurs in approximately 10 percent of patients with acalculous cholecystitis [14]. Perforation may result in a cholecystenteric fistula, abscess formation, or free perforation with generalized peritonitis. In patients with gangrene without perforation, complications include acute pancreatitis, colonic perforation, and obstruction of the common hepatic duct. These complications are discussed in detail separately. (See "Acute calculous cholecystitis: Clinical features and diagnosis", section on 'History'.)

DIAGNOSTIC APPROACH

Clinical suspicion and evaluation — Acalculous cholecystitis should be suspected in critically ill patients with sepsis without a clear source or jaundice. It should also be considered in patients with postoperative jaundice. (See "Classification and causes of jaundice or asymptomatic hyperbilirubinemia", section on 'Disorders associated with conjugated hyperbilirubinemia' and "Approach to the patient with postoperative jaundice", section on 'Acalculous cholecystitis'.)

We perform abdominal imaging with an ultrasonography in patients with suspected acalculous cholecystitis [9,19,24,25]. In patients in whom the diagnosis is uncertain, we perform abdominal imaging with a contrast-enhanced abdominal computed tomography (CT) scan for evidence of acute acalculous cholecystitis and to exclude other causes of acute abdominal pain. In stable patients in whom the diagnosis is unclear after ultrasonography and abdominal CT scan, we perform a hepatic iminodiacetic acid (HIDA) scan [26]. (See 'Imaging' below.)

Laboratory evaluation should include a complete blood count, electrolytes, liver tests, pancreatic enzymes. In addition, we perform a urine analysis to look for evidence of urosepsis, and a chest radiograph or CT scan to rule out pneumonia. Blood cultures should be obtained in all patients with suspected acalculous cholecystitis. Culture results can guide narrowing of empiric antibiotics. (See 'Antibiotics' below and "Antimicrobial approach to intra-abdominal infections in adults", section on 'Assessment of culture data'.)

Imaging — Imaging in acalculous cholecystitis is not specific enough to make the diagnosis alone. Imaging findings must be interpreted in the context of the clinical presentation. (See 'Diagnosis' below.)

Ultrasonography — Ultrasonography is noninvasive and can be performed at the bedside in critically ill patients. Radiologic features suggestive of acalculous cholecystitis include:

●3.5- to 4-mm (or more) thick wall (if the gallbladder is distended to at least 5-cm longitudinally, and the patient has no ascites or hypoalbuminemia)

●Sonographic Murphy's sign is defined as inspiratory arrest during deep breath while gallbladder is being insonated)

●Pericholecystic fluid (halo)/subserosal edema

Other imaging findings in patients with acalculous cholecystitis include:

●Intramural gas

●Sloughed mucosal membrane

●Echogenic bile (sludge)

●Hydrops (distension greater than 8-cm longitudinally or 5-cm transversely, with clear fluid)

The reported sensitivity of ultrasound for acalculous cholecystitis ranges from 30 to 92 percent [23,27]. However, these data are derived from small, mostly retrospective studies with use of different criteria for sonographic diagnosis.

The specificity of ultrasound for acalculous cholecystitis ranges from 89 to 100 percent [23,27]. Sonographic Murphy's sign is operator-dependent and requires an awake and cooperative patient, but, when present, is indicative of gallbladder inflammation. Thickening of the gallbladder wall is the most reliable feature seen in patients with acalculous cholecystitis but is not specific [23]. False positive results may be due to hypoalbuminemia, ascites, sludge, non-shadowing stones, or cholesterolosis which can mimic a thickened gallbladder wall.

Gallbladder abnormalities are detected in a significant number of critically ill patients even in the absence of acalculous cholecystitis. In one study of 44 critically ill patients, at least one sonographic abnormality was detected in 37 patients (84 percent) and up to three sonographic abnormalities were detected in 25 (57 percent). However, only two had acalculous cholecystitis [28].

Computed tomography — The accuracy of CT scan appears to be similar to that seen with ultrasonography [29,30]. CT scan findings suggestive of acalculous cholecystitis include [23]:

●Gallbladder wall thickening (>3 mm)

●Subserosal edema

●Pericholecystic fluid

●Mucosal sloughing

●Intramural gas

●Hyperdense bile (sludge)

●Gallbladder distention (>5 cm)

Gallbladder abnormalities are highly prevalent in critically ill patients and in one retrospective study of CT scan images of 127 critically ill patients, abnormal findings in the gallbladder were present in 96 percent. Of these findings, gas in the gallbladder wall or lumen, lack of gallbladder wall enhancement, and edema around the gallbladder have the highest specificity for acalculous cholecystitis (99, 95, and 92 percent, respectively), but these findings have poor sensitivity (11, 38, and 22 percent, respectively).

Cholescintigraphy — Technetium labeled HIDA is injected intravenously and is then taken up selectively by hepatocytes and excreted into bile. If the cystic duct is patent, the tracer will enter the gallbladder, leading to its visualization without the need for concentration. Normally, visualization of contrast within the common bile duct, gallbladder, and small bowel occurs within 30 to 60 minutes. Failure to opacify the gallbladder at one hour is considered a positive test. Leakage into the pericholecystic space suggests gallbladder perforation.

As cholescintigraphy (HIDA scan) takes hours to perform, it is not recommended in critically ill patients in whom a delay in therapy can be potentially fatal. The sensitivity of cholescintigraphy for acalculous cholecystitis ranges from 67 to 100 percent [31]. False negatives are rare but can occur in the following conditions [32]:

●Cystic duct patency despite a diseased gallbladder

●Bowel loop simulation of the gallbladder

●Bile leak from gallbladder perforation

●Tracer activity in the kidneys simulating the small bowel or the gallbladder

The specificity of cholescintigraphy for acalculous cholecystitis ranges from 58 to 88 percent [31]. The accuracy can be improved by injection of intravenous morphine in patients with nonvisualization of the gallbladder to increase bile secretory pressure, which promotes gallbladder filling in the absence of acalculous cholecystitis. If the gallbladder is not visualized in 30 minutes after morphine injection, it is considered a positive study. However, several conditions that can lead to false-positive results include:

●Severe hepatocellular disease can lead to abnormal uptake and excretion of the tracer.

●Fasting and administration of total parenteral nutrition can result in false positive results because the gallbladder is full due to prolonged lack of stimulation.

●Biliary sphincterotomy can result in low resistance for bile flow, leading to preferential excretion of the tracer into the duodenum without filling of the gallbladder.

●Severe illness is associated with poor emptying of the gallbladder due to the stress of systemic inflammation and ischemia.

●Rapid biliary to bowel transit.

●Prior cholecystectomy.

●Hyperbilirubinemia, which may be associated with impaired hepatic clearance of iminodiacetic acid compounds. Other agents (diisopropyl and m-bromothymethyl iminodiacetic acid) used in cholescintigraphy have generally overcome this limitation.

Diagnosis — The diagnosis of acalculous cholecystitis is based upon a constellation of symptoms and signs (eg, critically ill patients with sepsis without a clear source or jaundice) in the setting of supportive imaging findings, and the exclusion of alternative diagnoses. Imaging in acalculous cholecystitis is not specific enough to make the diagnosis alone and must be interpreted in the context of the clinical presentation.

The diagnosis of acalculous cholecystitis is often made in patients with all of the following:

●Fever, abdominal pain, leukocytosis and/or elevated liver tests (see 'Clinical manifestations' above)

●Risk factors for acalculous cholecystitis (table 1)

●Radiologic features suggestive of acalculous cholecystitis (eg, gallbladder wall thickening, sonographic Murphy’s sign, pericholecystic fluid) (see 'Imaging' above)

●No evidence of other conditions that could elicit the clinical and radiographic findings

DIFFERENTIAL DIAGNOSIS — The differential diagnosis of acalculous cholecystitis includes other causes of sepsis (eg, pneumonia, urinary tract infection), right upper quadrant pain and/or jaundice. These include:

●Acute calculous cholecystitis

●Acute pancreatitis

●Hepatic or subphrenic abscess

●Right-sided pyelonephritis

These conditions can be ruled out by clinical examination, laboratory tests, and imaging (eg, abdominal computed tomographic scan) performed as part of the evaluation in patients with suspected acalculous cholecystitis. (See 'Clinical suspicion and evaluation' above and 'Diagnostic approach' above and "Clinical manifestations and diagnosis of acute pancreatitis" and "Pyogenic liver abscess" and "Acute complicated urinary tract infection (including pyelonephritis) in adults and adolescents".)

MANAGEMENT — Prompt treatment of acalculous cholecystitis is imperative because without it, gallbladder gangrene may develop and can result in gallbladder perforation [19,23]. If treatment is delayed, mortality rates from acalculous cholecystitis may be as high as 75 percent [33,34]. With treatment, the mortality rate in acalculous cholecystitis is approximately 30 percent.

Overall approach — Patients diagnosed with acalculous cholecystitis require inpatient management, and based on their hemodynamic status, may need monitored or intensive care unit support. The management of acalculous cholecystitis includes supportive care with intravenous fluids, pain control, initiation of antibiotics (after blood cultures have been obtained), and definitive therapy with either cholecystectomy or gallbladder drainage (algorithm 1). Antibiotic therapy augments but does not replace definitive therapy because purulent material in the gallbladder needs to be removed or drained.

The initial choice between cholecystectomy or a gallbladder drainage procedure depends on the patient’s overall status, disease stage, and available local expertise:

●Patients with one of the indications for an emergency cholecystectomy can only be treated with cholecystectomy. Indications for an emergency cholecystectomy include:

•Gallbladder necrosis

•Emphysematous cholecystitis

•Gallbladder perforation

●Patients without indications for emergency cholecystectomy, who are critically ill or in poor health, or unfit for general anesthesia should be treated with gallbladder drainage. (See 'Gallbladder drainage' below.)

●Patients without indications for emergency cholecystectomy who are of low surgical and anesthetic risk (eg, ASA class I or II) can be treated with either cholecystectomy or gallbladder drainage. The decision should be made based on available local resources (surgeon, interventional radiologist, and endoscopist) and patient preference. Existing literature on this subject consists of either single-institution retrospective series [35,36], or large administrative database reviews [37,38], neither of which can be relied upon to make a definitive recommendation [39].

Patients typically respond to a gallbladder drainage procedure within 24 hours. Failure to improve (defined as persistent fever, signs of sepsis, or evidence of new multiorgan dysfunction) may be due to gangrenous cholecystitis, catheter dislodgement, bile leakage resulting in peritonitis, or an incorrect diagnosis of acalculous cholecystitis. In such patients, rescue cholecystectomy is required, or mortality is imminent.

Patients who are successfully treated with a gallbladder drainage procedure in combination with antibiotics may have the cholecystostomy tube removed when acalculous cholecystitis resolves and drainage is minimal (algorithm 1). Because the recurrence rate is low after true acute acalculous cholecystitis, and patients are generally high-risk, interval cholecystectomy is typically not required [40]. However, patients should undergo repeat abdominal ultrasound to exclude the presence of gallstones and sludge, the presence of which is an indication for surgery in suitable candidates. In patients undergoing cholecystectomy, the cholecystostomy tube is removed at the time of surgery. (See 'Management following gallbladder drainage' below.)

General measures for all patients

Supportive care — Supportive care includes intravenous hydration and correction of any associated electrolyte disorders, pain control, and treatment of the underlying predisposing cause.

Patients should be kept fasting, and although uncommonly needed, those who are vomiting should have placement of a nasogastric tube. Pain control in patients can usually be achieved with nonsteroidal anti-inflammatory drugs or opioids. Progression of pain during treatment for acute cholecystitis, despite adequate analgesia, is an indicator of a clinical progression.

Antibiotics — After blood cultures are obtained, intravenous broad spectrum antibiotics should be started. Acute cholecystitis is primarily an inflammatory process, but secondary infection of the gallbladder can occur as a result of cystic duct obstruction and bile stasis.

The choice of antibiotics should take into consideration whether the infection is community-acquired versus healthcare-associated, individual risk factors for infection with resistant bacteria and risk for adverse outcomes (table 3). We recommend the following antibiotic regimens for patients with acute cholecystitis based on their individual risk category [41]:

●For patients with community-acquired acute cholecystitis of low risk (table 4).

●For patients with community-acquired acute cholecystitis of high risk (table 5).

●For patients with healthcare-associated acute cholecystitis (table 6).

However, given that acalculous cholecystitis almost exclusively occurs in hospitalized patients who are acutely ill [42-44], most will have healthcare-associate acute cholecystitis.

The chosen antimicrobial agents should subsequently be tailored to culture and susceptibility results when they become available. The duration of antibiotics depends on the adequacy of control of infection and the clinically stability of the patient. Antibiotic therapy for intra-abdominal infections, including acute cholecystitis and the duration of therapy, are discussed in detail elsewhere. (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Empiric antimicrobial therapy'.)

Gallbladder drainage — Although cholecystectomy was traditionally the preferred definitive treatment for acalculous cholecystitis, gallbladder drainage has been established as a safe, effective, and definitive alternative to surgery.

Percutaneous cholecystostomy — Drainage of the gallbladder can be performed under radiologic guidance via a percutaneous cholecystostomy tube. Decompressing the gallbladder with a cholecystostomy allows both local inflammation and systemic illness to resolve [35,45-56]. Typically, a cholecystostomy tube is left in place until the acalculous cholecystitis has resolved. Patients with acalculous cholecystitis treated with cholecystostomy should improve rapidly (within 24 hours). (See 'Overall approach' above.)

The success rates for cholecystostomy range from 56 to 100 percent [35,45-56]. Complications include hemorrhage, sepsis, bile peritonitis, pneumothorax, intestinal perforation, secondary infection of the gallbladder, and catheter dislodgement [23,51,52,57,58].

Endoscopic drainage — Endoscopic gallbladder drainage is reserved for patients with acalculous cholecystitis in whom percutaneous approaches are contraindicated, or are not anatomically feasible (ie, advanced liver disease, ascites, or coagulopathy). Isolated cases of successful transpapillary endoscopic drainage of the gallbladder have been reported. Transpapillary drainage utilizes endoscopic retrograde cholangiography techniques and equipment to place a drainage catheter into the gallbladder via the cystic duct. The other end of the catheter is either brought out through the nose (nasobiliary drain) or left to drain internally into the duodenum.

An approach utilizing endoscopic ultrasound has been shown to be effective and similar to percutaneous drainage. This technique involves a trans-gastric approach from the antrum or proximal duodenum with endoscopic ultrasound guidance and can be used to place a metallic lumen-apposing stent that drains the gallbladder internally without need for an external drainage system [59].

Management following gallbladder drainage — Once the episode of acalculous cholecystitis has resolved, cholecystectomy is typically not required [47,48]. The risk of recurrent cholecystitis appears to be low among those treated with cholecystostomy drainage. In a retrospective study that included 57 patients with acalculous cholecystitis, of the 28 patients who were managed with percutaneous cholecystostomy, 2 (7 percent) had recurrent acalculous cholecystitis over a median 32 month follow-up [35].

Patients should undergo an abdominal ultrasound to evaluate for gallstones that may have been missed on prior imaging (algorithm 1).

●If gallstones or sludge are found, elective cholecystectomy should be performed in surgical candidates. The cholecystostomy tube should be left in place until the cholecystectomy. (See "Open cholecystectomy" and "Laparoscopic cholecystectomy" and "Complications of laparoscopic cholecystectomy".)

●In patients without gallstones or sludge, the cholecystostomy tube can be removed when there is minimal drainage (less than 10 cc per day). This is typically four to six weeks after cholecystostomy tube placement.

Cholecystectomy — Both open and laparoscopic approaches have been used for the surgical treatment of acalculous cholecystitis [3,19,60]. The gallbladder is often encased in an inflammatory mass, which makes laparoscopic cholecystectomy more complicated because of a higher risk of bile duct and vascular injuries. However, a laparoscopic approach is still preferred in critically ill patients. It is appropriate for the experienced surgeon to attempt a laparoscopic approach but convert to an open cholecystectomy if necessary. (See "Open cholecystectomy" and "Laparoscopic cholecystectomy" and "Complications of laparoscopic cholecystectomy".)

Timely cholecystectomy has been associated with survival rates of greater than 90 percent in patients with acute cholecystitis related to trauma, although lower survival rates would be expected in patients who develop acalculous cholecystitis in the setting of a critical illness [33].

PROGNOSIS — Acalculous cholecystitis is associated with a high mortality rate. Mortality in patients with acalculous cholecystitis depends upon coexistent medical or surgical conditions and the rapidity of diagnosis. Gallbladder necrosis, gangrene, and perforation are frequently present at the time of diagnosis, particularly in the critically ill, and are associated with poor outcomes [1,19]. The mortality rate can be as high as 90 percent in critically ill patients or as low as 10 percent in community-acquired cases [19,61]. Overall, the mortality rate is approximately 30 percent, which in part reflects the fact that acalculous cholecystitis typically develops in patients who are already critically ill [23]. If treatment is delayed, mortality rates may be as high as 75 percent [33,34]. The cause of death in most patients with acalculous cholecystitis is sepsis with multiorgan failure [62].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cholecystitis and other gallbladder disorders".)

SUMMARY AND RECOMMENDATIONS

●Epidemiology – Acalculous cholecystitis is an acute necroinflammatory disease of the gallbladder with a multifactorial pathogenesis. It accounts for approximately 10 percent of all cases of acute cholecystitis and is associated with high morbidity and mortality rates.

●Clinical manifestations – Acalculous cholecystitis is typically seen in patients who are hospitalized and critically ill, although it may also be seen in the outpatient setting (table 1). In critically ill patients, the appearance of unexplained fever, leukocytosis, or vague abdominal discomfort may be the only sign of acalculous cholecystitis. Because the presentation may be insidious, gallbladder necrosis, gangrene, and perforation are frequently present at the time of diagnosis. (See 'Clinical manifestations' above.)

●When to suspect and choice of imaging – Acalculous cholecystitis should be suspected in critically ill patients with sepsis without a clear source or jaundice. It should also be considered in patients with postoperative jaundice. We perform abdominal imaging with ultrasonography in patients with suspected acalculous cholecystitis. In patients in whom the diagnosis is uncertain, we perform a contrast-enhanced abdominal computed tomography (CT) scan for evidence of acute acalculous cholecystitis and to exclude other causes of acute abdominal pain. In stable patients in whom the diagnosis is unclear after ultrasonography and abdominal CT scan, we perform a hepatic iminodiacetic acid scan. (See 'Clinical suspicion and evaluation' above.)

●Diagnosis – Imaging in acute acalculous cholecystitis is not specific enough to make the diagnosis alone. The diagnosis of acute acalculous cholecystitis is based upon a constellation of symptoms and signs in the setting of supportive imaging findings, and the exclusion of alternative diagnoses. The diagnosis of acute acalculous cholecystitis is often made in patients with all of the following (see 'Diagnosis' above and 'Imaging' above):

•Fever, abdominal pain, leukocytosis and/or elevated liver tests

•Risk factors for acute acalculous cholecystitis (table 1)

•Radiologic features suggestive of acalculous cholecystitis

•No evidence of other condition that could elicit the clinical and radiographic findings

●Management

•General measures – Patients with acalculous cholecystitis require supportive care with intravenous fluids, correction of electrolyte abnormalities, bowel rest, and pain control (algorithm 1). In patients with acalculous cholecystitis, we recommend the initiation of broad spectrum antibiotics as soon as blood cultures have been drawn, rather than waiting for blood culture results (Grade 1B). The choice of antibiotics should take into consideration whether the infection is community-acquired versus healthcare-associated, individual risk factors for infection with resistant bacteria, and risk for adverse outcomes (table 3). (See 'Antibiotics' above.)

•Definitive treatment with drainage or cholecystectomy – We recommend definitive treatment with either cholecystectomy or cholecystostomy for patients with acalculous cholecystitis, rather than continued supportive care (Grade 1B). The initial choice between cholecystectomy or a gallbladder drainage procedure depends on the patient's overall status (indications for emergency cholecystectomy), disease stage, and available local expertise.

•Patients with the indications for an emergency cholecystectomy – Indications for an emergency cholecystectomy include:

-Gallbladder necrosis

-Emphysematous cholecystitis

-Gallbladder perforation

•Patients without indications for emergency cholecystectomy – In patients with acalculous cholecystitis who do not have indications for emergency cholecystectomy, we suggest cholecystostomy rather than cholecystectomy (algorithm 1) (Grade 2C). Cholecystostomy is effective and is less invasive than cholecystectomy. However, cholecystectomy is also a reasonable alternative in patients who are good surgical candidates.

Patients with acalculous cholecystitis who fail to improve within 24 to 48 hours following cholecystostomy require emergency cholecystectomy (algorithm 1). (See 'Overall approach' above and 'Gallbladder drainage' above and 'Cholecystectomy' above.)

●Prognosis – Acalculous cholecystitis is associated with a high mortality rate. Mortality in patients with acalculous cholecystitis depends upon coexistent medical or surgical conditions and the rapidity of diagnosis. The risk of recurrent cholecystitis appears to be low among those treated with cholecystostomy drainage. Once the episode of acalculous cholecystitis has resolved, cholecystectomy is typically not required in the absence of concurrent gallstones or sludge. (See 'Management following gallbladder drainage' above and 'Prognosis' above.)