Protocol for the management of liver abscess Department of Internal Medicine, PMHC

Liver abscesses maybe amoebic or polymicrobial (mixed enterbacteria). Amoebic abscess is by far the most common type of liver in our setting. Patients with polymicrobial abscess usually have underlying gastrointestinal or biliary tract disease, bacteria may have arrived in the liver from the portal vein or hepatic artery. Also these patients tend to be older then patients with amoebic abscess. Polymicrobial abscesses are also more likely to be multiple. Amoebic abscesses tend to be singular, in the right lobe of the liver and also occur predominantly in men. They are not often associated with amoebic dysentery although amoebic cysts can be found in the stools of >10% of patients with amoebic abscess. Clinical features both types of abscess may cause fever, right upper quadrant pain, right shoulder tip pain, jaundice maybe present if the abscess encroaches on the biliary tree. On examination the abscess maybe felt and in the case of amoebic abscess there maybe a fluctuant area where the abscess is about to burst through the skin. Either abscess may present acutely or sub-acutely. Pain may also be elicited on percussion of the lower right posterior chest wall. Diagnosis is made with ultrasound note should be taken of the number of abscesses seen, the site of the abscess and any associated liver or abdominal abnormality. Chest x-ray may shown right sided pleural effusion, or raised hemidiaphragm. Practical issues

1. Deciding if the abscess is polymicrobial or amoebic a. First make the diagnosis of liver abscess have a low threshold for carrying out an

ultrasound scan in patients with fever and right upper quadrant pain. Also consider the diagnosis in patients with right sided pleural effusion, raised right hemidiaphragm or fever of unknown origin

b. If the abscess is single treat as amoebic (other supporting features are younger patient, male and abscess in right lobe of liver)

c. If there are multiple abscesses treat as polymicrobial (also consider this diagnosis in older patients, patients with biliary disorders or patients with other gastrointestinal abnormalities from which bacteria may have spread.

2. Management a. Amoebic abscess

i. give metronidazole 800mg 8 hrly p.o. for 7 to 10 days. In a severely ill patient metronidazole 500mg 8hrly i.v.i. but this is rarely necessary.

ii. Aspiration of the abscess is not routinely required. But it is useful to aspirate the abscess if it is in the left lobe and may rupture into the pericardium, the hemidiaphragm is raised and the abscess may rupture into the pleural cavity or the abscess is about to point through the skin to prevent a fistula or amoebic peritonitis which has a high mortality. Also abcsesses greater then 10x10cm should be aspirated.

iii. Patients usually improve rapidly. There is not thought to be any resistance to metronidazole. If the patient is not improving aspirate the abscess and send the pus for culture. The reason for non improvement could be either that the abscess is polymicrobial or that it is too tense for the antibiotic to penetrate

iv. A luminal amoebocide should be given to clear amoebic cysts. b. Polymicrobial abscess

i. Aspirate pus under ultrasound guidance, take a blood culture, look for the source of infection and address this as appropriate.

ii. Give co-amoxiclav 1.2g 8hrly i.v.i. and metronidazole 500mg 8hrly i.v.i until the patient improves. Also in the severely ill patient consider adding gentamicin 5mg/kg i.v.i.. After days if the patient is improving oral co-amoxiclav can be given or another appropriate antibiotic depending on pus culture results.

iii. Assess the patient for diabetes, bowel carcinoma, biliary disease as appropriate. Ask advice from medical / surgical consultants on further management.