## Most Common Site of Extraintestinal Amoebiasis **Key Point:** The liver is the most common site of extraintestinal E. histolytica infection, accounting for 80–90% of all extraintestinal cases [cite:Park 26e Ch 8]. ### Pathophysiology Trophozoites invade the intestinal mucosa and breach the portal circulation via the superior mesenteric vein, lodging preferentially in the liver parenchyma. The right lobe is more frequently affected than the left due to portal blood flow distribution. ### Clinical Presentation of Amoebic Liver Abscess - **Acute phase:** fever, hepatomegaly, right upper quadrant tenderness, elevated transaminases - **Chronic phase:** weight loss, hepatomegaly, pain - **Imaging:** hypoechoic or anechoic lesion on ultrasound; "anchovy paste" appearance on aspiration (sterile, containing necrotic material) ### Frequency of Extraintestinal Sites | Site | Frequency (%) | Notes | |------|---------------|-------| | Liver | 80–90 | Most common; right lobe > left | | Lung | 5–10 | Secondary to liver abscess rupture | | Brain | 1–2 | Rare; high mortality | | Spleen | <1 | Uncommon; usually with liver involvement | | Kidney | <1 | Rare | **High-Yield:** Amoebic liver abscess is the most common cause of liver abscess in endemic areas (India, Africa, Mexico). In non-endemic areas, pyogenic abscess is more common. **Clinical Pearl:** Serology (indirect haemagglutination test, enzyme immunoassay) is positive in >90% of patients with amoebic liver abscess but only 10% with acute intestinal infection, making it a valuable diagnostic aid. **Tip:** When a patient from an endemic region presents with fever, hepatomegaly, and RUQ pain, always think amoebic liver abscess first—it is the most likely extraintestinal manifestation.
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.