NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Holzheimer RG, Mannick JA, editors. Surgical Treatment: Evidence-Based and Problem-Oriented. Munich: Zuckschwerdt; 2001.

Cover of Surgical Treatment

Surgical Treatment: Evidence-Based and Problem-Oriented.

Show details

Pyogenic and amebic liver abscess

, M.D., FACS and , M.D.

Author Information

Abscesses of the liver are known since the time of Hippocrates. Improvements in diagnostic and therapeutic modalities besides the postoperative care have significantly reduced the high mortality. The reduced mortality is related to early diagnosis and proper and prompt treatment. Liver abscesses are classified into two main groups, pyogenic and amebic related to the etiological cause.

Pyogenic abscess

The incidence of pyogenic liver abscess based on hospital admissions ranges from 0.029 to 1.47%(5) and 0.3 to 1.4% in autopsy studies (9). There is a decline in the incidence of pyogenic liver abscesses as well as a change in the relative frequency of pyogenic and amebic abscesses.

Pyogenic liver abscesses are caused from 1) diseases of the biliary tract, 2) infectious gastrointestinal disorders spreading via the portal vein, 3) hemotogeneous spread via the hepatic artery, 4) direct extension from an intraabdominal infection and 5) trauma. There has been a change in the trend of the etiological causes and the biliary tract diseases have replaced the infections through the portal route as the most common cause of pyogenic liver abscesses. The biliary tract diseases account for about 40%, whereas the portal route about 20% of the cases. Cryptogenic abscesses, with unknown etiology, still account for about 20% of pyogenic liver abscesses. Previously appendicitis was reported as the most important cause of the portal etiology, however diverticulitis, perforated ulcers and perforated cancers have become the leading cause in this category in recent years (3, 5, 8, 9). Geographical variations may be present in the etiological causes.

Bacteria entering the portal system are usually engulfed by the Kupffer cells in the liver. A liver abscess may form if the quantity of the organisms exceeds the capacity of the Kupffer cells in the presence of an underlying liver disease or if the host is immunucompromised. The hepatic artery is a source of contamination in cases of systemic bacteremia; i.e. subacute bacterial endocarditis. Biliary obstruction, i.e. stones, strictures or tumors, leads to the contamination of the bile and subsequent cholangitis resulting in multiple abscesses in the liver. Large abscess formation can be seen in oriental cholangiohepatitis secondary to biliary strictures. These abscesses are most commonly located in the lateral segment of the left lobe (6).

Pyogenic liver abscess is almost always the result of bacterial infection although on rare occasions fungal infections may be the underlying cause. Positive cultures are obtained in over ninety percent of the cases. Intestinal microorganisms such as Escherichia coli, Klebsiella, Proteus, Staphylococcus and Streptococcus are most commonly isolated. Anaerobic bacteria are seldomly cultured. Polymicrobial cultures are not frequent.

Fever and chills are the most common clinical manifestations. Right upper quadrant abdominal pain, jaundice, weight loss, nausea and vomiting are the other common manifestations. Rupture of the abscess with peritonitis may be seen occasionally. Sepsis may be present in 25% of the cases. Leukocytosis, hyperbilirubinemia, hypoalbuminemia and elevated serum alkaline phosphatase are common laboratory findings. Other liver function tests such as AST may also be mildly elevated.


Imaging techniques are extremely helpful in the diagnosis of hepatic abscesses. Plain abdominal x-rays may demonstrate gas within the abscess cavity (10–20%) and elevation of the diaphragm. Radioisotope scanning was the most common method used for a long period until new imaging techniques have been introduced. Ultrasonography (US) should be preferred as the initial diagnostic method. It has an accuracy rate of 80–90% in diagnosing intrahepatic abscesses larger than 2 cm in diameter with limitation in abscesses located in the dome of the liver. US findings demonstrate an irregular margin and a hypoechoic lesion. Gas within the cavity is detected by the presence of microbubbles or diffuse hyperechoic spots with reverberation (5, 6, 10). Although the findings are non-specific ultrasonography is also helpful in differentiating pyogenic and amebic abscesses.

Computerized tomography (CT) has the advantage of detecting intrahepatic collections as small as 0.5 cm. This advantage is significant in patients with multiple small pyogenic abscesses. Pyogenic abscesses may have well-defined round or oral cavities or lobulated with poorly marginated edges on CT. The internal density of the abscess is usually low (2–29 Housefield units). But it increases with contrast enhancement which increases the ease of diagnosis (7).

Both ultrasonography and computerized tomography contribute significantly in identification of liver lesions which further facilitates the diagnosis by needle aspiration. Analysis of the Gram stain of the aspirate will demonstrate polymorphonuclear leukocytes and bacteria in pyogenic abscesses.

Magnetic resonance (MR) is well established as a sensitive imaging method for detection of liver lesions. Some reports claim that it does not provide information of greater usefulness than US or CT. Runge et al. have reported that the conspicuity of an early liver abscess is improved markedly on delayed MR imaging with Gadolinium-BOPTA (12).

Prior to the introduction of high resolution imaging techniques, 30–50% of liver abscesses were not diagnosed until postmortem examination.


The treatment of pyogenic liver abscess should be individualized. Proper antibiotic treatment and adequate drainage is essential. The choice of treatment of pyogenic hepatic abscesses depends largely on the source and characteristics and the patient's underlying clinical condition. In general both antibiotic therapy and adequate drainage are required for the treatment of pyogenic liver abscesses in combination. Drainage has been accomplished either surgically; conventional open or laparoscopic, or percutaneously.

The choice of the antibiotics should cover the most common microorganisms cultured from liver abscesses. The underlying disease may be a clue to the possible microorganism for empirical treatment. Targeted antibiotic therapy can be commenced earlier based on culture of organism of the pus aspirated. Antibiotics used should be wide spectrum. The antibiotic therapy should consist of a combination of an aminoglycoside with either metronidazole or clindamycin, or a beta lactam antibiotic with anaerobic coverage. In case of Staphylococcal or Streptococcal infection a penicillinase resistant penicillin or first generation cefalosporin can be used for treatment. The antibiotic treatment in liver abscess secondary to biliary disease should consist of ampicillin or ureidopenicillin combined with an aminoglycoside. Antibiotic therapy alone should be reserved only for the patients in good clinical condition and those who has a solitary or micro abscesses smaller than 2 cm in diameter. The length of the antibiotic therapy should be individualized on the basis of the number of abscesses and the clinical response. Patients with multiple abscesses should receive antibiotics for 4–6 weeks (8, 10).

Drainage of pyogenic liver abscesses is the mainstay of the treatment. Drainage can be accomplished either surgically or US/CT guided percutaneously. Anesthetic risk of the patient, the presence or absence of a coexisting primary intraabdominal pathology, the success rate of the procedure and expertise in managing these pathologies are the factors which should be considered in selecting the choice of therapy.

Surgical management of pyogenic liver abscess entails an individualized approach based on the underlying clinical condition and the source of the abscess. “Source control” is essential in the surgial treatment of pyogenic liver abscess. Laparotomy and surgical drainage is essential in eliminating the source of infection that seeded the liver. Location of the abscess is important in determining the surgical approach. Abscess located in the dome of the liver can be approached through the bed of the 10–11th rib transpleurally. This approach has the advantage of avoiding peritoneal contamination but has the disadvantage of having a limited exposure. In recent series Bertel et al. have reported an overall 87% (92% in solitary abscess) and Herman et al. 91.5% success rate in transperitoneal surgical drainage (3, 8). Herman advocating surgical drainage as a good alternative as a first step in septic patients where a delay in adequate drainage can lead to high mortality and morbidity rates. Intraoperative ultrasonography may be helpful in localizing abscesses during the procedure.

Laparoscopic drainage has also been advocated in the literature. Tay et al. has reported 20 patients with liver abscess of which 18 were pyogenic and treated with laparoscopic drainage. The success rate was reported as 85% (15).

Percutaneous drainage of pyogenic liver abscess was initially performed by aspiration in 1953. The method was re-popularized with the advancement of imaging techniques. Dietrick et al. reported a mortality rate of 2.8% and a complication rate of 17.4% with aspiration. Ultrasonography or computerized tomography directed percutaneous drainage is now considered the treatment of choice for those without a surgically correctable disease. It has the advantage of avoiding a laparotomy. The reported success rate ranges between 70–90% with this modality (3, 7, 8). Tazawa et al. evaluated the results of percutaneous drainage in multiple pyogenic liver abscesses. They reported that percutaneous drainage is effective even in patients with multiple abscesses (14).

Although there are various reports comparing these modalities in the treatment of pyogenic liver abscesses there are no prospective randomized studies comparing the different treatment modalities. Herman et al. have reported a series of 48 patients with a treatment protocol comparing antibiotic therapy alone with percutaneous and surgical drainage in three groups with different disease severity.

Gyorffy et al. compared medical treatment, percutaneous and surgical drainage in a retrospective study reporting better results with surgical drainage in a total of 26 patients. These studies demonstrate clearly that the treatment of pyogenic liver abscess should be individualized and all treatment modalities which still have a place in the treatment.In a multivariate analysis Chou et al. reported that age > 60 years, blood urea nitrogen > 20 mg per dL, serum creatinine > 2 mg per dL, total bilirubin > 2 mg per dL and albumin < 2.5 gm per dL were independent significant factors predicting mortality in 352 pyogenic liver abscess patients (5).

Amebic liver abscess

Amebiasis has the highest incidence in subtropical and tropical climates and in areas with poor sanitation. Immunocompromised host are more prone to develop amebic liver abscess (13). Liver abscess complicates testinal amebiasis in 3–10% of the cases. The disease is secondary to infestation with Entamoeba histolytica. The cystic form of E. histolytica gain access to the host by oral ingestion of contaminated food or water. After digestion of the cyst, the trophozoites are released into the gastrointestinal tract, where they may reach the liver via the portal system by entering the mesenteric venules. The trophozoites cause cellular necrosis with the development of abscess in the liver. The amebic liver abscesses are usually solitary and surrounded by a thin walled granulation tissue. The right lobe is more commonly affected. The content of the amebic abscess is described to be like an “anchovy” sauce. These abscesses are usually sterile but secondary bacterial infection may develop (1, 6, 10).

The symptoms are similar to pyogenic liver abscess. The patients with amebic abscess are reported to be younger when compared to those with pyogenic liver abscess and are more likely to have traveled to an endemic area. The most common symptoms are abdominal pain and fever. History of diarrhea is present in 20–30% of the cases. Abdominal pain is reported to be more common in amebic abscess. Akgün et al. in a recent retrospective study comparing two different time span have reported abdominal pain to be present in 98% and fever in 74% of the cases. Hepatomegaly and tenderness over the liver are most frequent physical signs (1, 6, 10).

Serology is the best method of confirming the diagnosis of amebic liver abscess. Cysts of the protozoon are found in the stool in 1/4th of the patients.

The best way to confirm the diagnosis of amebic liver abscess is with serology testing. Indirect hemagglutination and gel diffusion precipitation are the most commonly used tests with 85–95% sensitivity and specificity detecting antibodies to E. histolytica. The cysts of the protozoon are found in the stool in about 1/4th of the patients.

Imaging techniques are extremely helpful in the diagnosis. Ultrasonography in the presence of an amebic abscess reveals a round or oval lesion with well defined margins and with lack of prominent peripheral echoes. The lesions are primarily hypoechoic, with fine homogeneous low-density echoes and show some distal sonic enhancement. CT-scan findings reveal low density with smooth margin and a contrast-enhancing peripheral rim with internal inhomogeneity (6, 10).

Secondary infection is the most common complication of amebic abscess. Rupture into adjacent cavities is the other important complication.

Secondary infection is the most common complication of amebic liver abscess (10–20%). Rupture of the abscess occurs either into the pleura, lung, pericardium or the peritoneum. Abscesses located in the dome of the liver may rupture through the diaphragm and cause empyema, pleural effusion, bronchopleural fistula (4–7%). On the other hand those located in the inferior surface tend to rupture into the peritoneal cavity (7–11%) (1).


Use the amebicidal drugs is the first line treatment of amebic liver abscess. Metronidazeole is the drug of choice. The size of the abscess is an important factor in determining the response to medical treatment. Percutaneous needle aspiration and/or catheter drainage are the other modalities of treatment. The treatment modalities are selected depending on the presence of complications. The first line treatment in uncomplicated amebic abscess should be amebicidial drugs. Metronidazole is the drug of choice and has replaced the use of emetine and chloroquine. Metronidazole is effective against both the intestinal and hepatic phase. 750 mg three times a day for 7–10 days is recommended. Abscess smaller than 5 cm in diameter respond better to metronidazole treatment.

Although routine aspiration is not recommended in most cases percutaneous needle aspiration is required for treatment, especially in larger abscesses. The success rate of percutaneous needle aspiration is in the range of 75–100%. In Akgün's series the success rate was reported as 87.5%. In case of failure with needle aspiration plus medical treatment US or CT guided catheter drainage can be used.

Surgical open drainage is indicated only for those with complicated amebic abscess, e.g. secondary infection or peritonitis with perforation.

Surgical open drainage is clearly indicated only in those who fail to respond to conservative methods and those with complicated abscesses. But even in the case of a free perforation into the peritoneal cavity, pleura or the pericardium conservative treatment with an amebicidal drug has been recommended. In case of peritonitis surgical drainage is indicated. The mortality increases significantly with laparotomy (1).


Akgün Y, Taçyιlιdιz Ï H, Çelik Y. Amebic liver abscess. Changing trends over 20 years. World J Surg. (1999);23:102–106. [PubMed: 9841772]
Barakate M S, Stephen M S, Waugh R C. et al. Pyogenic liver abscess: A review of 10 years’ experience in management. Aust NZ J Surg. (1999);69:205–209. [PubMed: 10075360]
Bertel C K, van Heerden J A, Sheedy P F. Treatment of pyogenic hepatic abscesses: Surgical vs percutaneous drainage. Arch Surg. (1986);121:554–558. [PubMed: 3707333]
Ch Yu S, Hg Lo R, Kan P S, Metreweli C. Pyogenic liver abscess: Treatment with needle aspiration. Clin Radiol. (1997);52:912–916. [PubMed: 9413964]
Chou F F, Sheen-Chen S M, Chen Y S. et al. Prognostic factors for pyogenic abscess of the liver. J Amer Coll of Surg. (1994);179:727–732. [PubMed: 7952485]
Donovon A J, Yellin A E, Ralls P W. Hepatic abscess. World J Surg. (1991);15:162–169. [PubMed: 2031354]
Gerzof S G, Johnson W C, Robbins A H, Nabseth D C. Intrahepatic pyogenic abscesses: Treatment by percutaneous drainage. Amer J Surg. (1985);149:487–494. [PubMed: 3885778]
Herman P, Pugliese V, Montagnini A L. et al. Pyogenic liver abscess: The role of surgical treatment. Int Surg. (1997);82:98–101. [PubMed: 9189815]
Mischinger H J, Hauser H, Rabl H. et al. Pyogenic liver abscess: Studies of therapy and analysis of risk factors. World J Surg. (1994);18:852–858. [PubMed: 7846908]
Pitt H A. Surgical management of hepatic abscesses. World J Surg. (1990);14:498–504. [PubMed: 2200212]
Rajak C L, Gupta S, Jain S. et al. Percutaneous treatment of liver abscesses: Needle aspiration versus catheter drainage. Amer J Radiol. (1998);170:1035–1039. [PubMed: 9530055]
Runge V L, Wells J W, Williams N M. Hepatic abscesses: Magnetic resonance imaging findings using Gadolinium-BOPTA. Investigative Radiology. (1996);31:781–788. [PubMed: 8970881]
Seeto R K, Rockey D C. Amebic liver abscess: Epidemiology, clinical features and outcome. West J Med. (1999);170:104–109. [PMC free article: PMC1305450] [PubMed: 10063397]
Tazawa J, Sakai Y, Maekawa S. et al. Solitary and multiple pyogenic liver abscesses: Characteristics of the patients and efficacy of percutaneous drainage. Amer J Gastroenterol. (1997);92:271–274. [PubMed: 9040204]
Tay K H, Ravintharan T, Hoe M N Y. et al. Laparoscopic drainage of liver abscess. Brit J Surg. (1998);85:330–332. [PubMed: 9529485]
Copyright © 2001, W. Zuckschwerdt Verlag GmbH.
Bookshelf ID: NBK6955


  • PubReader
  • Print View
  • Cite this Page

Related information

  • PMC
    PubMed Central citations
  • PubMed
    Links to PubMed

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...