AKT · Gastroenterology/Liverlow yield

Liver abscess

Pyogenic (biliary/portal spread, polymicrobial) or amoebic (Entamoeba histolytica)

Overview

A collection of pus in the liver — PYOGENIC (commonest in the UK; from biliary disease/ascending cholangitis, portal spread from appendicitis/diverticulitis, or haematogenous; often polymicrobial incl. E. coli, Klebsiella) or AMOEBIC (Entamoeba histolytica — travel/endemic, classically a single right-lobe 'anchovy-paste' abscess). Presents with fever, RUQ pain and deranged LFTs; treated with drainage + antibiotics (pyogenic) or metronidazole (amoebic).

Recognise

Swinging fever, rigors, RUQ pain, tender hepatomegaly, malaise/weight loss, raised inflammatory markers, deranged LFTs (raised ALP)
Pyogenic: older, biliary/abdominal source, often polymicrobial (Klebsiella, E. coli)
Amoebic: travel/endemic area, usually a SINGLE right-lobe abscess ('anchovy paste'), positive amoebic serology

Red flags

Sepsis; rupture (into pleura/peritoneum/pericardium)
Underlying source (biliary obstruction/cholangitis, colonic source)

Differentials & how to tell them apart

Pyogenic vs amoebictravel/single right-lobe + serology (amoebic) vs polymicrobial/biliary source (pyogenic)

Hydatid cystechinococcus — calcified/daughter cysts; do NOT aspirate (anaphylaxis)

HCC/metastasis with necrosismalignant context, imaging characteristics

Cholangitis/cholecystitisbiliary sepsis without a discrete liver collection

Investigations

USS/CT (the abscess); blood cultures, FBC/CRP/LFTs; amoebic serology + stool antigen; aspiration for culture (pyogenic). Identify the source (biliary/colonic).

Management

Pyogenic → drainage + IV antibiotics; amoebic → metronidazole

1Image (USS/CT) and take cultures/amoebic serology. PYOGENIC: percutaneous drainage + broad-spectrum IV antibiotics and treat the source. AMOEBIC: metronidazole (usually no drainage needed).Gate: Distinguish pyogenic (drain + antibiotics, find the biliary/colonic source) from amoebic (metronidazole, often no drainage) — travel history + single right-lobe abscess + serology points to amoebic; never aspirate a suspected HYDATID cyst (anaphylaxis)
2Treat the underlying source (biliary obstruction/colonic); follow imaging resolution; luminal amoebicide to clear carriage.

Pyogenic: drainage (percutaneous) + broad-spectrum IV antibiotics — cover Gram-negatives/anaerobes; treat the source

Amoebic: metronidazole (+ luminal agent) — usually responds medically; drainage if large/no response/rupture risk

Key points

Swinging fever + RUQ pain + raised ALP + liver collection = liver abscess. Pyogenic (drain + antibiotics, find the source) vs amoebic (travel, single right-lobe 'anchovy paste', metronidazole). Don't aspirate hydatid.

Monitor & prognosis

Resolution on imaging; source control.

Good with drainage/antibiotics; rupture is dangerous.

Source: BSG; StatPearls