- Entameoba histolytica is the most common cause in the UK
- Ascending cholangitis is the most common cause of pyogenic infection
- 'Wheel spoke sign' seen on ultrasound is highly suggestive of amoebic liver abscess
- Imaging guided aspiration is contraindicated in hydatid cysts
- Is known complication of hepatic chemoembolization
Answers: F, T, F, F, T
Notes: Entameoba histolytica is the most common cause in developing world, but in developed world, pyogenic is the most common cause. In pyogenic abscesses, the most common organism isolated in solitary absess is Klebsiella pneumoniae and in multiple abscess E.coli. The most common mode of spread of infection for pyogenic is ascending cholangitis; for amoebic portal; phlebitis and for fungal, hepatic artery. On ultrasound, the pyogenic abscesses are usually hypoechoic with poorly defined irregular wall and may show echogenic debris. The amoebic abscesses are typically hypoechoic with absence of significant wall. Various ultrasound signs have been described for hydatid cyst and include double contour thick wall (due to triple layer), snow storm sign (falling of sand after patient repositioning), water-lilly sign with floating membranes (detachment of endocyst) and wheel spoke sign (daughter cysts). Heptaic infection is known complications of chemoembolization and radiofrequency ablation
Reference: Doyle DJ et al. Imaging of hepatic infections. Clin Rad 61: 737-746
