A 42-year-old woman from Kolkata presents with a 2-month history of fever, right upper quadrant pain, and hepatomegaly. Ultrasound shows a 6 cm hypoechoic lesion in the right lobe of the liver with no internal septations. Stool microscopy is negative for parasites. Serology (IHA/ELISA) for E. histolytica is positive. What is the most appropriate next step in management?

Explanation

## Management of Amebic Liver Abscess (ALA) **Key Point:** Amebic liver abscess is diagnosed by the clinical triad of fever, hepatomegaly, and imaging findings PLUS positive serology. Stool microscopy is often negative (only 10–20% positive in ALA) because the infection is extraintestinal. Serology positivity (>90% in ALA) is the gold standard for diagnosis. ### Diagnostic Certainty in This Case | Finding | Significance | |---------|-------------| | Ultrasound: 6 cm hypoechoic lesion, no septations | Typical ALA appearance (homogeneous, no gas, no locules) | | Negative stool microscopy | Expected in extraintestinal disease; does not exclude ALA | | Positive serology (IHA/ELISA) | >90% sensitive in ALA; confirms amebic etiology | | Clinical presentation | Fever + RUQ pain + hepatomegaly = classic ALA | **High-Yield:** Serology alone is sufficient for diagnosis of ALA; aspiration/culture is NOT required for uncomplicated cases. ### Medical Management as First-Line **Clinical Pearl:** Uncomplicated amebic liver abscess (no rupture, no peritonitis, no shock) is managed medically in >90% of cases with excellent outcomes. Drainage is reserved for: - Abscess >5 cm with risk of rupture - Failure to improve after 5–7 days of medical therapy - Left lobe abscess (risk of pericardial rupture) - Rupture or peritonitis ### Two-Drug Regimen for ALA 1. **Metronidazole 750 mg TDS × 10 days** — kills trophozoites in abscess wall and surrounding liver parenchyma 2. **Paromomycin 25–35 mg/kg/day ÷ 3 doses × 7 days** — eliminates luminal cysts (prevents relapse and transmission) **Mnemonic:** **METRO for tissue, PAROMO for lumen** = Complete eradication of both invasive and luminal stages. ### Why Aspiration is NOT Routine - Aspiration does NOT improve cure rates in uncomplicated ALA - Risk of secondary bacterial infection if needle passes through bowel - Serology + imaging is diagnostic; culture is low-yield (E. histolytica is difficult to culture) - Aspiration reserved for diagnostic uncertainty or therapeutic drainage [cite:Harrison 21e Ch 237; Robbins 10e Ch 8]