Liver Abscess

Introduction

Liver abscesses typically result from a polymicrobial bacterial infection spreading from the biliary or gastrointestinal tract, either via contiguous spread or seeding from the portal and hepatic veins.

Common causes include cholecystitis, cholangitis, diverticulitis, appendicitis, or septicaemia

The most commonly isolated organisms are E. Coli, K. pneumoniae, and S. constellatus, although fungal causes may also be present in immunocompromised patients.

Clinical Features

Patients typically present with fever, rigors, and abdominal pain*. Other symptoms include bloating, nausea, anorexia, weight loss, fatigue and jaundice.

On examination, patients will have RUQ tenderness +/- hepatomegaly. If the abscess ruptures (a rare complication), then patients may present with signs of shock.

*Pyogenic abscess should be considered in all patients presenting with pyrexia of unknown origin associated with associated abdominal pain or bloating

Investigations

FBC will show a leucocytosis and LFTs are often abnormal, with a raised ALP in most cases and deranged ALT and bilirubin in a proportion. All patients should also have peripheral blood and fluid cultures sent for microscopy.

Ultrasound imaging will reveal poor-defined lesions with hypo- and hyper-echoic areas, with potential gas bubbles and septations.

Further delineation can be achieved by CT imaging with contrast (Figure 1), revealing a similar pattern from the collection as seen on US with associated surrounding oedema.

By Hellerhoff / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Figure 1 – CT scan showing a liver abscess, seen as a hypodense lesion with peripheral enhancement

Management

Patients should be fluid resuscitated and stabilised accordingly, and started on appropriate antibiotic therapy (guided by sensitivities and local policies)

Most cases can be drained via image-guided aspiration of the abscess (with or without catheter drainage), either US or CT, for source control. Any underlying cause should also be addressed once the patient has been appropriately managed

Surgery is rarely indicated, predominantly if the abscess has ruptured or refractory to antibiotic treatment.

Amoebic Abscess

An amoebic abscess is the most common extra-intestinal manifestation of amebiasis infection, caused by the organism Entamoeba histolytica.

The infection spreads via faeco-oral route. Once in the colon, the trophozoite begins to invade the mucosa and spread to the liver via the portal system.

By CDC/Dr. Mae Melvin; Dr. E. West of Mobile, AL

Figure 2 – An amoebic liver abscess

It is estimated that 12% of the world’s population is infected with this organism, most commonly in developing regions such as South America, the Indian subcontinent, and Africa.

Clinical Features

Patients will present with vague symptoms of abdominal pain, nausea, fever or rigors, weight loss, and bloating. Cases should be suspected in patients with a history of recent travel (<6 months) to an endemic region.

Patients may present with a prodrome of clinical features secondary to the intestinal involvement, including abdominal pain and diarrhoea.

Investigations

Bloods will show a leucocytosis with deranged LFTs. All patients should also have peripheral blood and fluid cultures sent for microscopy. Blood and stool samples should also be sent to check for the presence of E. histolytica antibodies, if suspected.

Ultrasound imaging will reveal poor-defined lesions which can be further characterised by CT imaging.

Management

Most patients can be treated with antibiotics alone, typically metronidazole or tinidazole are the antimicrobials of choice.

In large cysts or those which do not respond well to antibiotic therapy, surgical drainage may be required. A luminal agent such as paromomycin can also be prescribed to eradicate amoebiasis in the colon.