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Difficulty: MediumGastroenterology and Hepatology

A 38-year-old man comes to the clinic complaining of a 3-week history of right upper quadrant abdominal pain, low-grade fevers, and profound fatigue. He emigrated from an endemic region of Central America 4 months ago. He does not use tobacco, alcohol, or illicit drugs. His temperature is 38.3°C (100.9°F), blood pressure is 122/78 mm Hg, and pulse is 88/min. Physical examination shows a liver edge that is palpable 3 cm below the right costal margin with marked point tenderness over the lower right rib cage. A complete blood count reveals a leukocyte count of 13,500/mm³ with 75% neutrophils. An abdominal ultrasound reveals a solitary, hypoechoic, 5-cm fluid collection in the right hepatic lobe. Enzyme immunoassay for *Entamoeba histolytica* antibodies is positive. Which of the following is the most appropriate next step in management?

  1. Administration of oral metronidazole followed by paromomycinAnswer
  2. B
    CT-guided percutaneous catheter drainage
  3. C
    Intravenous piperacillin-tazobactam
  4. D
    Intravenous ceftriaxone and metronidazole
  5. E
    Diagnostic fine-needle aspiration for culture and sensitivity

Answer

Administration of oral metronidazole followed by paromomycin
The correct approach involves administering a tissue amebicide to eradicate the invasive systemic infection, followed by a luminal agent to eliminate intestinal colonization. The patient's presentation of a solitary liver lesion, travel history, and positive serology definitively confirms an amebic liver abscess caused by *Entamoeba histolytica*. Unlike pyogenic liver abscesses, amebic abscesses typically do not require aspiration or percutaneous drainage unless they are at high risk of rupture or refractory to medical therapy.

Step-by-Step Solution

1
Identify the clinical syndrome from the presentation.
The patient has a liver abscess, evidenced by right upper quadrant pain, fever, leukocytosis, and a solitary fluid collection on hepatic ultrasound.
Recognizing the core pathology limits the differential diagnosis to primarily pyogenic versus amebic liver abscess.
2
Differentiate the etiology based on epidemiological and laboratory data.
The patient's travel history and positive enzyme immunoassay for *Entamoeba histolytica* definitively identify the lesion as an amebic liver abscess.
Accurate etiological differentiation is critical because pyogenic and amebic abscesses require fundamentally different management strategies.
3
Select the appropriate targeted therapy.
Medical management with a tissue amebicide (metronidazole) followed by a luminal agent (paromomycin) is chosen over antibiotics or drainage.
Amebic liver abscesses typically resolve with targeted medical therapy alone and do not require routine percutaneous drainage.

Key Concept

Management of amebic liver abscess requires a tissue amebicide followed by an intraluminal agent, and rarely necessitates procedural drainage.
Estimated Time:1m 15s
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Topics

Gastroenterology and Hepatology

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