A 56-year-old man is evaluated for fever on postoperative day 3. He had undergone coronary artery bypass surgery for multivessel coronary artery disease, requiring 4 grafts. The patient is still intubated and is receiving mechanical ventilation. He has a history of type 2 diabetes mellitus, hypercholesterolemia, and hypertension. Temperature is 38.9 C (102 F), blood pressure is 130/80 mm Hg, and pulse is 90/min. BMI is 28 kg/m². Examination reveals coarse breath sounds bilaterally. Heart sounds are normal. The patient grimaces during palpation of the right upper quadrant. Bowel sounds are decreased. Laboratory results are as follows: Chest x-ray reveals postoperative changes but no new infiltrate. Which of the following is the most likely diagnosis in this patient?

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Quizplus · Accepted Answer

11ec25c8_d8e2_ed54_bc81_f384524d1829_MD0003_00 This patient's presentation suggests acalculous cholecystitis, an acute inflammation of the gallbladder in the absence of gallstones. Acalculous cholecystitis is most often seen in hospitalized patients who are critically ill. Common predisposing conditions include recent surgery (particularly cardiopulmonary, aortic, or abdominal), severe trauma, extensive burns, sepsis or shock, prolonged fasting or total parenteral nutrition, or critical illness requiring mechanical intubation. These conditions likely cause gallbladder stasis or ischemia with local inflammation that can lead to gallbladder distension, necrosis, and secondary bacterial infection. Acalculous cholecystitis can present with unexplained fever and diffuse or right upper quadrant (RUQ) abdominal pain. Other findings can include jaundice, RUQ mass, leukocytosis, or abnormal liver function tests (normal results do not exclude the diagnosis). Therefore, the diagnosis requires a high degree of suspicion. Complications include gangrene, perforation, and emphysematous cholecystitis. Abdominal ultrasound is usually preferred for diagnosis and can reveal signs of acute cholecystitis without gallstones. Patients with unclear ultrasound findings may need an abdominal CT scan or cholescintigraphy (hepatobiliary iminodiacetic acid) scans, which are more sensitive and specific for the diagnosis. (Choice B) Acute cholangitis is usually due to common bile duct obstruction by a gallstone or malignancy. It typically presents with fever, jaundice, RUQ abdominal pain, and elevated alkaline phosphatase. Therefore, acute cholangitis is less likely given this patient's normal alkaline phosphatase and absence of jaundice. (Choice C) Acute pancreatitis can occur postoperatively in patients with hypotension (similar to acalculous cholecystitis). However, acute pancreatitis is less likely due to this patient's RUQ, rather than epigastric, tenderness and normal amylase levels. (Choice D) Right lower lobe pneumonia can present with fever, cough, and sometimes RUQ pain. However, pneumonia is less likely given the absence of new infiltrate on this patient's chest x-ray. (Choice E) Right-sided pyelonephritis usually presents with fever, nausea, and right flank (not RUQ) pain. (Choice F) Subphrenic abscess (rare) can cause fever and abdominal pain. However, it usually develops due to peritonitis (eg, perforated ulcer, appendicitis, abdominal surgery) and is unlikely in this patient who did not undergo an abdominal procedure. Educational objective: Acute acalculous cholecystitis is an acute inflammation of the gallbladder in the absence of gallstones that is most commonly seen in hospitalized and critically ill patients. References: Acute acalculous cholecystitis: a review. (http://www.ncbi.nlm.nih.gov/pubmed/19747982)

A 56-Year-Old Man Is Evaluated for Fever on Postoperative Day