A 70-year-old man comes to the hospital due to worsening right upper quadrant pain, fever, and anorexia for the past 2 days. Today, he also developed chills. The patient was treated for acute diverticulitis 4 weeks ago. Medical conditions also include type 2 diabetes mellitus and hypertension. He does not use tobacco, alcohol, or illicit drugs. The patient has not traveled recently. Temperature is 39.3 C (102.7 F), blood pressure is 130/80 mm Hg, pulse is 98/min, and respirations are 18/min. Examination shows no jaundice. The right upper quadrant is markedly tender with some guarding on palpation. Bowel sounds are normal, and there is no ascites. Laboratory results are as follows:
| Hemoglobin | 11.2 g/dL |
| Leukocytes | 19,000/mm3 |
| Total bilirubin | 1.7 mg/dL |
| Aspartate aminotransferase (SGOT) | 90 U/L |
| Alanine aminotransferase (SGPT) | 80 U/L |
| Alkaline phosphatase | 190 U/L |
CT scan of the abdomen is shown in the exhibit:
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Blood cultures are obtained. Which of the following is the best next step in diagnosis?
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This patient with fever, right upper quadrant pain, leukocytosis, and elevated liver enzymes has a rounded, hypoattenuating lesion in the liver, which is concerning for pyogenic liver abscess. Pyogenic liver abscess can occur due to direct extension from biliary tract infections, penetrating trauma, or hematogenous spread from the systemic (eg, infectious endocarditis) or portal circulation (eg, intraabdominal infection). This patient likely developed the abscess as a result of his recent diverticulitis, which allowed for the spread of bacteria from the inflamed intestines through the portal circulation.
Manifestations typically include fever, right upper quadrant pain (which may be severe), leukocytosis, and elevated liver function studies. The diagnosis is confirmed with abdominal imaging; CT scan classically demonstrates a well-defined, hypoattenuating, rounded lesion, often surrounded by a peripherally enhancing abscess membrane.
Management includes blood cultures, antibiotics, and percutaneous aspiration and drainage, which is both diagnostic (eg, culture, Gram stain) and therapeutic; catheter placement is often required to drain large lesions. Surgical drainage can be considered for abscesses not amenable to percutaneous intervention.
(Choice B) Malaria can present with fevers, anemia, and hyperbilirubinemia; however, it would not be expected to cause right upper quadrant pain or a hypoattenuating liver lesion on CT scan. It would also be unexpected in a patient who has not traveled recently.
(Choice C) Echinococcus granulosus causes cystic liver lesions in individuals exposed to infected sheep or canines; patients are typically asymptomatic unless the cysts are large or rupture. Cysts are typically visible on a CT scan as thin-walled, septated lesions, occasionally with calcification.
(Choices D and F) Entamoeba histolytica is a major cause of hepatic abscess; however, most patients with amebic liver abscess have a history of exposure in endemic areas (eg, India, Mexico). This diagnosis should be considered in patients without other, more common causes of abscess (unlike this patient with recent diverticulitis). Testing options include serology or stool analysis (eg, ova and parasite).
(Choice E) This patient is at increased risk for Clostridioides (formerly Clostridium) difficile infection due to his recent hospitalization and antibiotic treatment for diverticulitis. However, C difficile infection is characterized by persistent, watery diarrhea and would not be expected to cause abscess formation.
Educational objective:
Pyogenic liver abscess typically presents with fevers, right upper quadrant pain, leukocytosis, and altered liver function tests. It can result from direct spread from the biliary tract or from hematogenous seeding of distal infection, particularly those involving the portal system (eg, diverticulitis). Diagnosis requires abdominal imaging, and management includes blood cultures, antibiotics, aspiration, and drainage.