Atypical Acalculus Cholecystitis

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Today Dr. Lu presented an interesting case of acalculus cholecystitis that prompted us to remember that when the data does not match our clinical picture, we need to reassess. The key take home points are:

  1. Re-visit the differential diagnosis when the data does not match the original diagnosis
  2. Consider testing characteristics when approaching imaging
  3. In the right clinical context, consider repeat imaging

It is more typical to see calculus cholecystitis than acalculus. Calculus cholecystitis can be seen in patients with RUQ pain, fever and leukocytosis. However, there is no single finding that has a strong enough liklihood ratio to establish or exclude the diagnosis thus, imaging is required (see Trowbridge et. al. 2003 for more details). While those with acalculus cholecystitis typically have a more variable presentation but, are often critcally ill. It is key to assess for risk factors for acalculus cholecystitis which include:

AAC risk factors.png

Imaging is also key in acalculus cholecystitis. However, with few studies and relatively low numbers, the sensitivity ranges from 29-92% with U/S and 67-100% with HIDA (see [Barie 2010][1], Huffman 2010 and Mariat 2000 for more information). And, one cannot forget the possibilty of a falsely negative study. While a false-negative HIDA scan is rare, it can happen. As was seen in this patient.

[1]: Barie PS, Eachempati SR. Acute acalculous cholecystitis. Gastroenterol Clin North Am 2010; 39:343.

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Ultimately, management is supportive care with IV fluids and pain control in addition to antibiotic and source control. Antibiotics include single agent (Pip-Tazo, Ertapenem, Meropenem, etc) or combination therapy with Metronizadole (+ Ceftriaxone, Cipro, Cefepime, etc). If there is imaging suggestive of necrosis, emphysematous gallbladder or perforation then, emergency cholecystectomy is indicated. Additionally, if there is no improvement in 24-48hours, repeat imaging vs. ongoing antibiotics vs. cholecystectomy may be indicated. In this case, repeat imaging revealed a perforated gallbladder and the patient was taken for emergent cholecystectomy.