A liver abscess is a collection of pus within the liver caused by infection. Pus consists of dead white blood cells, microorganisms and tissue debris. Infection triggers an inflammatory response, recruiting neutrophils and macrophages and releasing cytokines, which walls off the infected area to form the abscess cavity. If untreated, the cavity may enlarge as pus accumulates and intracavitary pressure rises, which increases the risk of rupture into adjacent spaces.
Types of liver abscess
Liver abscesses are usually classified by the causative organism:
Pyogenic (bacterial) liver abscess — this is the most common type. It is usually caused by bacteria such as Klebsiella pneumoniae, Escherichia coli, Streptococcus anginosus (milleri group), Staphylococcus aureus, or various anaerobes. In many cases, more than one type of bacteria is involved. People with conditions such as diabetes or bile duct disease are at higher risk.
Amoebic liver abscess — this type is caused by the parasite Entamoeba histolytica. The parasite usually infects the intestines and can spread to the liver through the bloodstream. Amoebic abscesses are more common in parts of the world where this infection is widespread and can become dangerous if not treated quickly.
Fungal liver abscess — these are rare and usually occur in people with severely weakened immune systems, such as those receiving chemotherapy or living with prolonged neutropenia. Candida is the most common fungus involved, though Aspergillus may also cause abscesses.
Parasitic infections with hepatic abscess-like lesions (rare) — some parasitic infections, such as Fasciola hepatica (liver fluke) or, in very rare cases, Ascaris lumbricoides (roundworm), can produce liver lesions that resemble abscesses. However, hydatid disease caused by Echinococcus forms fluid-filled cysts rather than true pus-filled abscesses.
A liver abscess is a serious condition in which pus collects inside the liver, usually caused by bacteria, parasites, or fungi spreading from the intestines, bile ducts, bloodstream or nearby infections.
What causes liver abscesses?
A liver abscess forms when germs reach the liver and cause infection. This can happen in several ways:
From the bile ducts — blockages or infections in the bile ducts, such as gallstones or cholangitis allow bacteria to spread directly into the liver.
From the intestines — bacteria or parasites in the gut can travel to the liver through the portal vein, especially after bowel perforation or inflammation.
Through the bloodstream — infections elsewhere in the body, such as pneumonia or skin infections, can spread to the liver via the blood.
From abdominal infections — conditions like appendicitis or peritonitis may allow bacteria to spread into the liver.
From contaminated food or water — amoebic and parasitic liver abscesses are often linked to unsafe water or eating raw or undercooked food, especially in areas where these infections are common.
In people with weakened immunity — fungal infections can occasionally cause liver abscesses, especially in patients on chemotherapy, long-term steroids, or with advanced HIV.
What are the signs and symptoms of liver abscesses?
Liver abscesses can be difficult to recognise because their symptoms are often vague and overlap with many other conditions. However, people with liver abscesses frequently experience:
Fever and chills
Nausea and vomiting
Night sweats
Fatigue or a general feeling of being unwell
Abdominal pain, usually in the upper right side
Cough or pain that spreads to the chest or shoulder
Shortness of breath
Loss of appetite or unintentional weight loss
Enlarged and tender liver (hepatomegaly)
Jaundice (yellowing of the skin and eyes)
Dark-coloured urine
Because these symptoms are not specific, timely medical assessment is essential. Left untreated, a liver abscess can lead to serious complications.
Liver abscess can cause abdominal pain, usually in the upper right side, because of inflammation and swelling of the liver.
Who is at risk of liver abscesses in Singapore?
Liver abscesses can occur in anyone, but certain factors increase the likelihood of developing one:
Age — older adults, young children and newborns are generally more vulnerable to infections because their immune defences may be weaker or not fully developed.
Cirrhosis — liver cirrhosis makes patients more prone to liver abscesses, as it impairs the liver’s normal filtering function and weakens the immune response.
Weakened immunity — individuals with compromised immune systems, such as those undergoing chemotherapy, living with HIV, receiving long-term steroids or having had an organ transplant, face a greater risk of infections including liver abscesses.
Biliary tract disease — conditions such as gallstones, cholangitis (infection of the bile ducts) or obstruction of the bile ducts are common causes of pyogenic liver abscesses, as bacteria can spread directly from the biliary system into the liver.
Medications — some studies suggest that prolonged use of proton pump inhibitors (PPIs), which reduce stomach acid, may slightly increase the risk of pyogenic liver abscess. This is thought to be linked to changes in gut bacteria, though the exact mechanism remains uncertain.
How are liver abscesses diagnosed?
Early diagnosis of a liver abscess is crucial, as untreated abscesses can rupture and lead to life-threatening complications. Because the symptoms are often non-specific and resemble other conditions, several tests are usually needed to confirm the diagnosis and identify the underlying cause.
Physical examination — your doctor will check for signs such as an enlarged and tender liver (hepatomegaly) or pain in the upper right side of the abdomen. They will also review your medical history and ask about recent travel, food and water sources or other possible exposures. It is important to mention any underlying health conditions or medications you are taking.
Blood tests — these may include a complete blood count (to check for infection), liver function tests, inflammatory markers such as C-reactive protein and blood cultures. They help assess liver health and detect bacteria in the bloodstream.
Stool tests — used mainly when an amoebic or parasitic liver abscess is suspected. They can detect parasite cysts, eggs or other evidence of intestinal infection.
Imaging tests — ultrasound, CT scans or MRI are the most common methods used to visualise the liver and detect abscesses. Imaging helps determine the size, number and location of abscesses, and also guides drainage procedures if needed.
Culture and aspiration — a sample of pus from the abscess, obtained through a needle aspiration or drainage, can be tested to identify the exact organism causing the infection. This guides doctors in selecting the most effective treatment.
What are the complications of liver abscesses?
If not treated promptly, a liver abscess can lead to serious and potentially life-threatening complications. These include:
Abscess rupture — an untreated abscess may burst, releasing pus into the abdominal cavity or nearby structures, which can spread the infection.
Peritonitis — if pus leaks into the abdominal cavity, it can inflame the peritoneum (the lining of the abdomen), causing severe pain, fever and systemic illness.
Spread of infection — the infection can extend to nearby organs such as the lungs or spread into the bloodstream, leading to widespread illness.
Lung complications — if the abscess ruptures upwards through the diaphragm, pus can track into the chest cavity, causing pleural effusion (fluid around the lungs) or empyema (pus in the pleural space). This may result in cough, chest pain and breathing difficulties.
Sepsis and septic shock — when bacteria enter the bloodstream, sepsis may occur. In severe cases, this can progress to septic shock, marked by dangerously low blood pressure, poor blood flow, organ failure and a high risk of death without urgent medical treatment.
What are the treatment options for liver abscesses in Singapore?
Treatment of liver abscesses depends on the underlying cause, but usually involves a combination of drainage procedures and medication.
Drainage — removing the pus from the abscess is often essential, particularly for larger abscesses. This can be done in several ways:
Percutaneous drainage — a minimally invasive procedure performed under ultrasound or CT guidance, where a needle or catheter is inserted through the skin to remove pus. Needle aspiration is usually used for small abscesses, while catheters are preferred for larger ones (typically over 5 cm).
Laparoscopic drainage — a keyhole procedure using small abdominal incisions and a laparoscope (a thin tube with a camera) to access and drain the abscess.
Surgical drainage — now less common, but still necessary in certain situations such as multiple or very large abscesses, thick-walled abscesses, ruptures, peritonitis or when percutaneous methods are unsuccessful.
Antibiotics — broad-spectrum antibiotics are usually started immediately, and later tailored based on culture results. Commonly used agents include third-generation cephalosporins, metronidazole and aminoglycosides. Treatment is often given intravenously at first, followed by oral medication, and may last several weeks.
Antifungal medications — used in rare cases of fungal liver abscess, most often in people with weakened immune systems. Drugs such as amphotericin B, fluconazole or flucytosine may be prescribed.
Antiparasitic medications — in amoebic or other parasitic abscesses, antiparasitic agents are essential. Metronidazole is the mainstay for Entamoeba histolytica, sometimes followed by other medicines (e.g. paromomycin) to clear intestinal infection. Other drugs such as albendazole, mebendazole, triclabendazole or praziquantel may be used depending on the specific parasite involved.
With timely treatment, most patients recover well. The choice of treatment is tailored to the type of infection, the size and number of abscesses and the patient’s overall health.
Summary
A liver abscess is a pocket of pus that forms in the liver due to bacterial, parasitic, or, less commonly, fungal infections. Symptoms such as fever, abdominal pain, fatigue and jaundice are often vague and may be mistaken for other conditions, which is why early diagnosis is so important. Tests such as blood work, imaging scans and aspiration of the abscess help doctors confirm the cause and guide treatment.
Management usually involves a combination of drainage procedures and targeted medicines, such as antibiotics for bacterial causes, antiparasitics for amoebic or worm-related abscesses and antifungal therapy for rarer fungal cases. Treating underlying risk factors, such as gallstones, diabetes or weakened immunity, is also an essential part of long-term recovery. Without timely treatment, liver abscesses can rupture and lead to life-threatening complications including peritonitis, sepsis and even septic shock.
If you are experiencing persistent fever, abdominal discomfort, or other symptoms suggestive of a liver abscess, schedule a consultation with Tan Siong San Surgery for a thorough evaluation, accurate diagnosis and tailored treatment plan.
Frequently Asked Questions (FAQs)
It can be. Without treatment, a liver abscess may rupture or spread infection to the blood and other organs, which can be fatal.
A liver abscess is caused by infection and contains pus, while cysts are fluid-filled sacs and tumours are abnormal growths. Imaging and lab tests help distinguish them.
Most abscesses are treated with antibiotics and needle or catheter drainage. Surgery is only needed if these measures fail, or in cases of rupture or multiple large abscesses.
Hospital stays vary but often last one to two weeks for drainage and intravenous antibiotics, followed by oral medication at home.
Yes, with proper treatment most patients recover completely, although follow-up imaging is usually needed to ensure the abscess has resolved.
They can return if the underlying cause, such as gallstones, bowel disease or uncontrolled diabetes, is not treated.
A balanced diet with adequate protein supports healing. Avoid alcohol and follow your doctor’s advice if you have other liver conditions.
No, you cannot “catch” a liver abscess from someone else. However, amoebic infections that lead to abscesses can spread through contaminated food or water.
Yes, if you seek medical help promptly for unexplained fever, abdominal pain or jaundice. Ultrasound and CT scans can pick it up early.
Yes, repeat imaging and blood tests are often done to confirm the abscess has cleared and to monitor for recurrence.
Most people heal without long-term damage, though very large abscesses or delayed treatment can sometimes scar the liver.
This article has been medically reviewed by Dr. Tan Siong San
Dr Tan is a Senior Consultant Surgeon with over 25 years of clinical experience in the field of Hepato-Pancreato-Biliary (HPB) surgery treating conditions affecting gallbladder, liver and pancreas.
