Emphysematous Cholecystitis

Full of Gas
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Diagnosis and reasoning

An adage which pediatricians love to repeat is that 'children are not little adults' - their physiology and patterns of disease vary widely by age. Similarly, the elderly are not just 'old adults'; as a result of the physiological processes of aging, they have their own unique spectrum of disease. In addition, the elderly often present later in the course of illness, tend to have more nonspecific symptoms, and may have comorbidities which mask the causative etiology. Last but not least, the physical examination of an older patient can be misleadingly benign - even with potentially fatal conditions. The patient in this case is an excellent example in point. At first glance, his presentation appears to be relatively benign - upper abdominal pain associated with minimal tenderness in the right upper quadrant. Given the absence of fever, and system-specific symptoms, it is all too easy to become complacent. However, note the presence of a pulse rate of over 90 bpm, along with a respiratory rate of > 20 cycles/minute; these two findings satisfy the criteria for systemic inflammatory response syndrome (SIRS), and suggest that serious pathology is at play. It also also important to appreciate that in retrospective studies, over 50% of older patients presenting with an acute abdomen required hospital admission, while 20% to 33% required immediate surgery. Thus, a very careful evaluation should always be performed in this age group; considering the right upper quadrant (RUQ) location of the pain and tenderness, potentially catastrophic conditions which need to be excluded include acute pancreatitis, acute cholecystitis and occult perforation of a viscus. His basic investigations turn out to be normal, except for the full blood count showing a leukocytosis (and thus fulfilling yet another criteria of SIRS); note also that the presence of normal amylase and lipase levels makes acute pancreatitis less likely. Imaging of the abdomen should be the next step in his workup; ultrasonography is the recommended first-line imaging study in patients with RUQ pain, but turns out to be inconclusive here. However, the abdominal radiograph proves to be fruitful by demonstrating an area of hyperlucency in the RUQ - a very unusual finding. The differential diagnosis of a hyperlucent area in the RUQ includes overlying bowel gas, retroperitoneal air, hepatic abscess, enterobiliary fistula, gallstone ileus, emphysematous cholecystitis (EC), an incompetent sphincter of Oddi, and focal biliary lipomatosis. However, note the presence of a poorly visualized gallbladder; when considered along with the above, this finding is most suspicious of EC. Thus, further visualization of the abdomen via computerized tomography (CT) is essential. The CT scan clinches the diagnosis by demonstrating the presence of gas inside the lumen and wall of the gallbladder. Thus, the diagnosis is EC indeed. EC is a life threatening condition which mandates emergent cholecystectomy; while percutaneous cholecystostomy is also a therapeutic option, this is best reserved for patients in whom surgery is contraindicated. IV antibiotics are also an essential component of the therapy; insulin should be started in order to bring his blood glucose under control.


Discussion

Emphysematous cholecystitis (EC) is a rare, life-threatening variant of acute cholecystitis characterized by the presence of gas in the gallbladder lumen, wall, or pericholecystic tissue. EC displays several traits which are markedly different from those of acute cholecystitis. First and foremost, men are affected more frequently than women, at a 2:1 ratio (as opposed to acute cholecystitis, where women are affected more often). In addition, the majority of these patients are of an older age group, being between 50 to 70 years of age, while around half have diabetes mellitus (DM), often complicated by peripheral arterial disease (PAD). Another important difference is that gallstones are found in only around 40% of cases of EC (while being found in approximately 90% of cases of acute cholecystitis); these patients also at higher risk of gallbladder perforation and gangrene. The pathophysiology underlying EC is believed to be vascular compromise of the cystic artery resulting in ischemia of the gallbladder; this would explain the male predilection and association with risk factors for atherosclerotic disease. The clinical presentation is similar to that of acute cholecystitis, with right upper quadrant pain and fever being the most common presenting symptoms; nausea and vomiting are also seen in almost half of patients. Examination often reveals tenderness in the right upper quadrant; an enlarged tense gallbladder may be palpable, and Murphy's sign may be positive. Note that the presence of peritonism is an ominous sign, signalling likely perforation, as is the development of clinical findings suggestive of sepsis or shock. It is very important to appreciate that similar to other gas forming infections, EC may initially manifest with insidious signs and symptoms, and then progress extremely rapidly, requiring emergent surgical intervention. It is almost impossible to differentiate EC from acute cholecystitis; imaging is key for the diagnosis. Plain radiographs of the abdomen can be used for the diagnosis; based on their radiographic appearance, the disease can be divided into 3 stages: Stage 1: gas within the gallbladder lumen Stage 2: gas within the gallbladder wall Stage 3: gas within the pericholecystic tissues Note that the presence of pneumoperitoneum is strongly suggestive of gallbladder perforation. Ultrasound most often demonstrates hyper-reflective echoes with distal reverberations originating from the gallbladder; a more specific (but less common) finding is the presence of small, nonshadowing echogenic foci rising up from the dependent portions of the gallbladder lumen, similar to effervescing bubbles in a glass of champagne (the "champagne sign"). Note that false negatives may occur if surrounding pericholecystic air obscures the gallbladder or mimics adjacent air-filled bowel. In addition, multiple stones within a contracted gallbladder can mimic the sonographic appearance of EC, as can the calcified walls seen in a porcelain gallbladder; thus, it is essential to perform additional radiography to confirm the presence of gas. CT is the most sensitive and specific imaging modality for identifying gas within the gallbladder lumen or wall; intravenous (IV) or oral contrast agents are usually not required, while pneumobilia, free intraperitoneal air, and portal venous gas are reliably identified. Note that in selected patients, Magnetic Resonance Imaging (MRI) may also play a supplemental role by providing information on intramural necrosis as well as intraluminal gas. Considering laboratory investigations, most patients demonstrate a neutrophil leukocytosis; serum bilirubin levels may also be elevated. Cultures of gallbladder fluid are positive in 95% of patients; the commonest organisms isolated are Clostridium spp, Escherichia coli, and Klebsiella spp. Once the diagnosis of EC is made, cholecystectomy should be performed as early as possible, as the disease can progress rapidly; both open or laparoscopic techniques can be used. In patients in whom surgery is contraindicated, percutaneous drainage of the gallbladder is usually the initial procedure of choice All patients should receive immediate antibiotic therapy; this should cover anaerobes, enteric Gram-negative organisms, and Gram-positive organisms (especially enterococci). Note that some authorities recommend hyperbaric oxygen therapy as an adjuvant to surgery, in order to reduce growth of anaerobic organisms; however, there is yet insufficient evidence to determine its efficacy. Overall, the mortality rate of EC is reported to be 15% (as compared to 4% for acute cholecystitis); early diagnosis and treatment is key towards reducing morbidity and mortality in this population.


Take home messages

  1. EC is a life threatening illness characterized by the presence of gas in the gallbladder lumen, wall, or pericholecystic tissue.
  2. Unlike acute cholecystitis, EC predominantly occurs in the elderly, is more common in males, and has a strong association with diabetes.
  3. EC cannot be differentiated from acute cholecystitis via clinical findings alone; diagnostic imaging is essential.
  4. EC may initially manifest with insidious signs and symptoms, and then progress extremely rapidly.
  5. The presence of peritonism or pneumoperitoneum is suggestive of gallbladder perforation.

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