Biliary tract obstruction (stone, tumor, stricture) with development of abscess secondary to cholangitis; spread from adjacent cholecystitis
Seeding during ERCP, biopsy, surgery
Spread via portal vein from intra-abdominal infection (appendicitis, diverticulitis, other) or direct extension (e.g. cholecystitis)
Trauma involving liver or abdominal structures
GI tract translocation secondary to malignancy (e.g. colon, gastric) or for unclear reasons
Seeding from systemic bacteremia, IVDU
Often etiology is cryptogenic
Amoebic: acquired via unclean water/poor sanitation, also anal intercourse
Echinococcus: typically traveler from Africa, Europe, Asia, the Middle East; Central and South America; very rare de novo in North America; exposure via working w/sheep/dogs, consumption of soil/water/food (containing eggs) contaminated w/feces from infected animals
Symptoms
F
C
Right upper quadrant pain
Sometimes nausea, fatigue, weight loss, diarrhea, jaundice and other less specific symptoms
Can be rather sub-acute, developing over weeks or longer
With severe illness, can have symptoms from spread of abscess (metastasis) to other sites
W/amebiasis, may have bloody diarrhea prior
Severe illness if abscess ruptures, w/intra-abdominal spread
Physical Exam Findings
Fever
Sometime severe illness/sepsis
Pain on palpation right upper quadrant
Sometimes palpable mass (varies w/size of abscess)
Tests
CT or US to identify abscess (and to facilitate drainage)
Serologies can be helpful for amebiasis and echinococcus (evidence of infection)