Liver Abscess
Bacterial abscess of the liver is relatively rare. It has been
described since the time of Hippocrates (400 BC), with the
first published review by Bright appearing in 1936. In 1938,
Ochsner's classic review heralded surgical drainage as the
definitive therapy; however, despite the more aggressive
approach to treatment, the mortality rate remained at 6080%.
Computed tomography (CT)
scan findings of liver abscess
are shown. A large, septated
abscess of the right hepatic
lobe is revealed. Abscess was
percutaneous drainage and
antimicrobial therapy.
Computed tomography scan
findings of liver abscess are
shown. A large anterior
abscess involving the left
hepatic lobe is revealed.
treated with percutaneous
drainage and antimicrobial
The development of new radiologic techniques, the
improvement in microbiologic identification, and the
advancement of drainage techniques, as well as improved
supportive care, have decreased mortality rates to 5-30%;
yet, the prevalence of liver abscess has remained relatively
unchanged. Untreated, this infection remains uniformly fatal.
The 3 major forms of liver abscess, classified by etiology, are
as follows:
1. Pyogenic abscess, which is most often polymicrobial,
accounts for 80% of hepatic abscess cases in the United
2. Amebic abscess due to Entamoeba histolytica accounts
for 10% of cases.
3. Fungal abscess, most often due to Candida species,
accounts for less than 10% of cases.
The liver receives blood from both systemic and portal
circulations. Increased susceptibility to infections would be
expected given the increased exposure to bacteria. However,
Kupffer cells lining the hepatic sinusoids clear bacteria so
efficiently that infection rarely occurs. Multiple processes
have been associated with the development of hepatic
abscesses; their relative frequencies are listed in the image
Appendicitis was traditionally the major cause of liver
abscess. As diagnosis and treatment of this condition has
advanced, its frequency as a cause for liver abscess has
decreased to 10%.
Biliary tract disease is now the most common source
of pyogenic liver abscess (PLA). Obstruction of bile flow
allows for bacterial proliferation. Biliary stone disease,
obstructive malignancy affecting the biliary tree, stricture,
and congenital diseases are common inciting conditions.
With a biliary source, abscesses usually are multiple, unless
they are associated with surgical interventions or indwelling
biliary stents. In these instances, solitary lesions can be seen.
Infections in organs in the portal bed can result in a localized
septic thrombophlebitis, which can lead to liver abscess.
Septic emboli are released into the portal circulation, trapped
by the hepatic sinusoids, and become the nidus for
microabscess formation. These microabscesses initially are
multiple but usually coalesce into a solitary lesion.
Microabscess formation can also be due to hematogenous
dissemination of organisms in association with systemic
bacteremia, such as endocarditis and pyelonephritis. Cases
also are reported in children with underlying defects in
immunity, such as chronic granulomatous disease and
Approximately 4% of liver abscesses result from fistula
formation between local intra-abdominal infections.
Despite advances in diagnostic imaging, cryptogenic causes
account for a significant proportion of cases; surgical
exploration has impacted this minimally. These lesions
usually are solitary in nature.
Penetrating hepatic trauma can inoculate organisms directly
into the liver parenchyma, resulting in pyogenic liver abscess.
Nonpenetrating trauma can also be the precursor to
pyogenic liver abscess by causing localized hepatic necrosis,
intrahepatic hemorrhage, and bile leakage. The resulting
tissue environment permits bacterial growth, which may lead
to pyogenic liver abscess. These lesions are typically solitary.
Pyogenic liver abscess has been reported as a secondary
infection of amebic abscess, hydatid cystic cavities, and
metastatic and primary hepatic tumors. It is also a known
complication of liver transplantation, hepatic artery
embolization in the treatment of hepatocellular carcinoma,
and the ingestion of foreign bodies, which penetrate the liver
parenchyma. Trauma and secondarily infected liver
pathology account for a small percentage of liver abscess
The right hepatic lobe is affected more often than the left
hepatic lobe by a factor of 2:1. Bilateral involvement is seen
in 5% of cases. The predilection for the right hepatic lobe can
be attributed to anatomic considerations. The right hepatic
lobe receives blood from both the superior mesenteric and
portal veins, whereas the left hepatic lobe receives inferior
mesenteric and splenic drainage. It also contains a denser
network of biliary canaliculi and, overall, accounts for more
hepatic mass. Studies have suggested that a streaming effect
in the portal circulation is causative.
United States
The incidence of pyogenic liver abscess has essentially
remained unchanged by both hospital and autopsy data.
Liver abscess was diagnosed in 0.7%, 0.45%, and 0.57% of
autopsies during the periods of 1896-1933, 1934-1958, and
1959-1968, respectively. The frequency in hospitalized
patients ranges from 8-16 cases per 100,000 persons. Studies
suggest a small, but significant, increase in the frequency of
liver abscess.
Untreated, pyogenic liver abscess remains uniformly fatal.
With timely administration of antibiotics and drainage
procedures, mortality currently occurs in 5-30% of cases. The
most common causes of death include sepsis, multiorgan
failure, and hepatic failure.2
While abscesses once showed a predilection for males in
earlier decades, no sexual predilection currently exists. Males
have a poorer prognosis from hepatic abscess than females.
1. Prior to the antibiotic era, liver abscess was most
common in the fourth and fifth decades of life, primarily
due to complications of appendicitis. With the
development of better diagnostic techniques, early
antibiotic administration, and the improved survival of
the general population, the demographic has shifted
toward the sixth and seventh decades of life. Frequency
curves display a small peak in the neonatal period
followed by a gradual rise beginning at the sixth decade
of life.
2. Cases of liver abscesses in infants have been associated
with umbilical vein catheterization and sepsis.
3. When abscesses are seen in children and adolescents,
underlying immune deficiency, severe malnutrition, or
trauma frequently exists.
1. See the image below for the presenting symptoms and
signs in 715 patients described in the literature.
2. The most frequent symptoms of hepatic abscess include
the following:
o Fever (either continuous or spiking)
o Chills
o Right upper quadrant pain
o Anorexia
o Malaise
3. Cough or hiccoughs due to diaphragmatic irritation may
be reported.
4. Referred pain to the right shoulder may be present.
5. Individuals with solitary lesions usually have a more
insidious course with weight loss and anemia of chronic
disease. With such symptoms, malignancy often is the
initial consideration.
Fever of unknown origin (FUO) frequently can be an
initial diagnosis in indolent cases. Multiple abscesses
usually result in more acute presentations, with
symptoms and signs of systemic toxicity.
7. Afebrile presentations have been documented.
1. Fever and tender hepatomegaly are the most common
2. A palpable mass need not be present.
3. Mid epigastric tenderness, with or without a palpable
mass, is suggestive of left hepatic lobe involvement.
4. Decreased breath sounds in the right basilar lung zones,
with signs of atelectasis and effusion on examination or
radiologically, may be present.
5. A pleural or hepatic friction rub can be associated with
diaphragmatic irritation or inflammation of Glisson
6. Jaundice may be present in as many as 25% of cases and
usually is associated with biliary tract disease or the
presence of multiple abscesses.
Polymicrobial involvement is common, with Escherichia
coli and Klebsiella pneumoniae being the 2 most frequently
isolated pathogens. Reports suggest that K pneumoniae is an
increasingly prominent cause.3 The image below lists the
common etiologic agents.
1. Enterobacteriaceae are especially prominent when the
infection is of biliary origin. Abscesses involving K
pneumoniae have been associated with multiple cases of
2. The pathogenic role of anaerobes was underappreciated
until the isolation of anaerobes from 45% of cases of
pyogenic liver abscess was reported in 1974. Since that
time, increasing rates of anaerobic involvement have
been reported, likely because of increased awareness
and improved culturing techniques. The most frequently
are Bacteroides species, Fusobacterium species,
microaerophilic and anaerobic streptococci. A colonic
source is usually the initial source of infection.
3. Staphylococcus aureus abscesses usually result from
hematogenous spread of organisms involved with distant
infections, such as endocarditis. S milleri is neither
anaerobic nor microaerophilic. It has been associated
with both monomicrobial and polymicrobial abscesses in
patients with Crohn disease, as well as with other
patients with pyogenic liver abscess.
4. Amebic liver abscess is most often due to E histolytica.
Liver abscess is the most common extraintestinal
manifestation of this infection.
5. Fungal abscesses primarily are due to Candida
albicans and occur in individuals with prolonged
exposure to antimicrobials, hematologic malignancies,
solid-organ transplants, and congenital and acquired
immunodeficiency. Cases involving Aspergillus species
have been reported.
6. Other organisms reported in the literature
include Actinomyces species, Eikenella
Yersinia enterocolitica, Salmonella typhi, and Brucella
Differential Diagnoses
Biliary Disease
Hydatid Cysts
Pneumonia, Bacterial
Empyema, Pleuropulmonary
Gastritis, Acute
Hepatocellular Carcinoma
Other Problems to Be Considered
Hepatitis, nonviral
Metastatic disease of the liver
Laboratory Studies
1. CBC count with differential
o Anemia of chronic disease
o Neutrophilic leukocytosis
2. Liver function studies
 Hypoalbuminemia and elevation of alkaline phosphatase
(most common abnormalities)
 Elevations of transaminase and bilirubin levels (variable)
3. Blood cultures are positive in roughly 50% of cases.
4. Culture of abscess fluid should be the goal in establishing
microbiologic diagnosis.
5. Enzyme immunoassay should be performed to detect E
histolytica in patients either from endemic areas or who
have traveled to endemic areas.
Imaging Studies
1. The advancement in radiologic techniques has been
credited with the improvement in mortality rates.
2. Computed tomography (CT) scan evaluation with
contrast and ultrasonography remain the radiologic
modalities of choice as screening procedures and also
can be used as techniques for guiding percutaneous
aspiration and drainage.
3. With advancements in multidetector CT scan technology,
image quality has improved dramatically, allowing for
improved detection.
4. CT scan (sensitivity 95-100%; see images below.)
 Lesions on CT evaluation are well-demarcated areas
hypodense to the surrounding hepatic parenchyma.
Peripheral enhancement is seen when IV contrast is
 Gas can be seen in as many as 20% of lesions.
 CT scan is superior in its ability to detect lesions less than
1 cm.
 This technique also enables the evaluation for an
underlying concurrent pathology throughout the
abdomen and pelvis. Indium-labeled WBC scans are
somewhat more sensitive in this regard.
5. Ultrasonography (sensitivity 80-90%)
Ultrasonographic evaluation reveals hypoechoic masses
with irregularly shaped borders. Internal septations or
cavity debris may be detected.
 Ultrasonography allows for close evaluation of the biliary
tree and simultaneous aspiration of the cavity.
 The major benefits of this technique are its portability
and diagnostic utility in patients who are too critical to
undergo prolonged radiologic evaluation or to be moved
out of monitored setting.
 Operator dependence affects its overall sensitivity.
6. Gallium and technetium radionuclide scanning
(sensitivity 50-90%)
 The initial studies are used in diagnosis.
 These
radiopharmaceuticals share the same uptake, transport,
and excretion pathways as bilirubin and, thus, are
effective agents in evaluating liver disease.
 Sensitivity varies with the radiopharmaceutical utilized,
technetium (80%), gallium (50-80%), and indium (90%).
 Limitations include a delay in diagnosis and the need for
confirmatory procedures; thus, they offer no benefit
over other imaging modalities.
7. Chest radiographic findings of basilar atelectasis, right
hemidiaphragm elevation, and right pleural effusion are
present in approximately 50% of cases; before
advancements in radiologic technique, these served as
diagnostic clues. Pneumonias or pleural diseases often
are initially considered because of the radiographic
1. Percutaneous needle aspiration
 Under CT scan or ultrasound guidance, needle aspiration
of cavity material can be performed.
 Needle aspiration enables rapid recovery of material for
microbiologic and pathologic evaluation.
 Needle aspiration can be performed with the initial
diagnostic procedure.
2. Percutaneous catheter drainage
 Percutaneous drainage has become the standard of care
and should be the first intervention considered for small
 For cysts greater than 5 cm, ruptured cysts, and
multiloculated cysts, surgical drainage is generally
recommended over percutaneous intervention.
 Advantages include reduced costs, recovery time, and
postprocedure recovery rate; it eliminates the need for
general anesthesia. This also allows for gradual,
controlled drainage.
 A catheter is placed under ultrasound or CT guidance
using the Seldinger or trocar techniques.
 The catheter is flushed daily until output is less than 10
cc/d or cavity collapse is documented by serial CT
Medical Care
1. An untreated hepatic abscess is nearly uniformly fatal
due to complications that include sepsis, empyema, or
peritonitis from rupture into the pleural or peritoneal
spaces, and retroperitoneal extension. Treatment should
include drainage, either percutaneous or surgical.
2. Antibiotic therapy as a sole treatment modality is not
routinely advocated, though it has been successful in a
few reported cases.
 It may be the only alternative in patients too ill to
undergo invasive procedures or in those with multiple
abscesses not amenable to percutaneous or surgical
 In these instances, patients are likely to require many
months of antimicrobial therapy with serial imaging and
close monitoring for associated complications.
3. Antimicrobial treatment is a common adjunct to
percutaneous or surgical drainage.
Surgical Care
Surgical drainage was the standard of care until the
introduction of percutaneous drainage techniques in the mid
1970s. With the refinement of image-guided techniques,
percutaneous drainage and aspiration have become the
standard of care.
1. Current indications for the surgical treatment of
pyogenic liver abscess are for the treatment of
underlying intra-abdominal processes, including signs of
peritonitis; existence of a known abdominal surgical
pathology (eg, diverticular abscess); failure of previous
drainage attempts; and the presence of a complicated,
multiloculated, thick-walled abscess with viscous pus.
2. Shock with multisystem organ failure is a
contraindication to surgery.
3. Open surgery can be performed by 2 approaches.
 A transperitoneal approach allows for abscess drainage
and abdominal exploration to identify previously
undetected abscesses and the location of an etiologic
 For high posterior lesions, a posterior transpleural
approach can be used. Although this allows easier access
to the abscess, the identification of multiple lesions or a
concurrent intra-abdominal pathology is lost.
Until cultures are available, the choice of antimicrobial
agents should be directed toward the most commonly
involved pathogens. Regimens using beta-lactam/betalactamase inhibitor combinations, carbapenems, or secondgeneration cephalosporins with anaerobic coverage are
excellent empiric choices for the coverage of enteric bacilli
and anaerobes. Metronidazole or clindamycin should be
added for the coverage of Bacteroides fragilis if other
employed antibiotics offer no anaerobic coverage.
Amebic abscess should be treated with metronidazole, which
will be curative in 90% of cases. Metronidazole should be
initiated before serologic test results are available. Patients
who do not respond to metronidazole should receive
chloroquine alone or in combination with emetine or
Systemic antifungal agents should be initiated if fungal
abscess is suspected and after the abscess has been drained
percutaneously or surgically. Initial therapy for fungal abscess
is currently amphotericin B. Lipid formulations may offer
some benefit in that the complexing of drug to lipid moieties
Multiple abscesses have been drained successfully by
this method.
 Failure to respond to catheter drainage is the main
reported complication and is also an indication for
surgical intervention.
 Other complications reported (rarely) are bleeding at the
catheter site, perforation of hollow viscus, and
peritonitis from intraperitoneal spillage of cavity fluid.
 Contraindications include coagulopathy; a difficult access
path to the cavity; peritonitis; and/or a complicated,
multiloculated, thick-walled abscess with viscous pus.
A laparoscopic approach is also commonly used in select
cases. This minimally invasive approach affords the
opportunity to explore the entire abdomen and to
significantly reduce patient morbidity. A growing
literature is defining the optimal population for this
mode of intervention.
5. A retrospective chart review compared surgery versus
percutaneous drainage for liver abscesses greater than 5
cm. The morbidity was comparable for the 2 procedures,
but those treated with surgery had fewer secondary
procedures and fewer treatment failures.
6. Postoperative complications are not uncommon and
include recurrent pyogenic liver abscess, intra-abdominal
abscess, hepatic or renal failure, and wound infection.
1. Interventional radiology: Obtain a consultation as soon
as the diagnosis is considered to allow rapid collection of
cavity fluid and the potential for early therapeutic
drainage of abscess.
2. General surgery
 Immediately seek a consultation with a general surgeon
if the source of the abscess is a known underlying
abdominal pathology or in cases with peritonitis.
 In cases undergoing percutaneous drainage, seek the
involvement of a general surgeon if drainage of the
abscess cavity is unsuccessful.
3. Gastroenterology involvement may be useful after
successful drainage to evaluate for underlying
gastrointestinal disease using colonoscopy or endoscopic
retrograde cholangiopancreatography (ERCP).
4. Infectious disease consultation should be considered in
complicated cases and when the involved pathogens are
unusual or difficult to treat, such as in fungal abscesses.
allows for concentration in hepatocytes. Further investigation
is required for definitive proof. Cases of successful
fluconazole treatment after amphotericin failure have been
reported; however, its use as an initial agent is still being
Ultimately, the organisms isolated and antibiotic sensitivities
should guide the final choice of antimicrobials.
Duration of treatment has always been debated. Short
courses (2 wk) of therapy after percutaneous drainage have
been successful in a small series of patients; however, most
series have reported recurrence of abscess even after more
prolonged courses. Currently 4-6 weeks of therapy is
recommended for solitary lesions that have been adequately
drained. Multiple abscesses are more problematic and can
require up to 12 weeks of therapy. Both the clinical and
radiographic progress of the patient should guide the length
of therapy.
Empiric antimicrobial therapy must be comprehensive and
should cover all likely pathogens in the context of the clinical
Meropenem (Merrem)
Bactericidal broad-spectrum carbapenem antibiotic that
inhibits cell-wall synthesis. Effective against most grampositive and gram-negative bacteria.
Has slightly increased activity against gram negatives and
slightly decreased activity against staphylococci and
streptococci species compared to imipenem.
1.0 g IV q8h
40 mg/kg IV q8h
Imipenem and cilastatin (Primaxin)
For treatment of multiple organism infections in which other
agents do not have wide-spectrum coverage or are
contraindicated due to potential for toxicity.
Base initial dose on severity of infection, and administer in
equally divided doses; dose may range from 250-500 mg IV
q6h for maximum of 3-4 g/d
Alternatively, 500-750 mg IM q12h or intra-abdominally
<12 years: Not established; 15-25 mg/kg/dose IV q6h
suggested for > 3 months
Fully susceptible organisms: Not to exceed 2 g/d IV
Infections with moderately susceptible organisms: Not to
exceed 4 g/d
Cefuroxime (Ceftin)
Second-generation cephalosporin maintains gram-positive
activity that first-generation cephalosporins have; adds
against Proteus
mirabilis, Haemophilus
influenzae, Escherichia
coli, Klebsiella
and Moraxella catarrhalis. Condition of patient, severity of
infection, and susceptibility of microorganism determine
proper dose and route of administration.
500 mg PO bid for 20 d
Children: 250 mg PO bid for 20 d
Adolescents: Administer as in adults
Cefotetan (Cefotan)
Second-generation cephalosporin indicated for infections
caused by susceptible gram-positive cocci and gram-negative
Dosage and route of administration depends on condition of
patient, severity of infection, and susceptibility of causative
1-2 g IV/IM q12h for 5-10 d
20-40 mg/kg/dose IV/IM q12h for 5-10 d
Cefoxitin (Mefoxin)
Second-generation cephalosporin indicated for gram-positive
cocci and gram-negative rod infections. Infections caused by
cephalosporin-resistant or penicillin-resistant gram-negative
bacteria may respond to cefoxitin.
1-2 g IV q6-8h
Infants and children: 80-160 mg/kg/d IV divided q4-6h;
higher doses for severe or serious infections; not to exceed
12 g/d
Cefaclor (Ceclor)
Second-generation cephalosporin indicated for infections
caused by susceptible gram-positive cocci and gram-negative
Determine proper dosage and route based on condition of
patient, severity of infection, and susceptibility of causative
250-500 mg PO q8h
20-40 mg/kg/d PO divided q8-12h; not to exceed 2 g/d
Clindamycin (Cleocin)
Lincosamide for treatment of serious skin and soft tissue
staphylococcal infections. Also effective against aerobic and
anaerobic streptococci (except enterococci). Inhibits bacterial
growth, possibly by blocking dissociation of peptidyl t-RNA
from ribosomes causing RNA-dependent protein synthesis to
150-450 mg/dose PO q6-8h; not to exceed 1.8 g/d
600-1200 mg/d IV/IM divided q6-8h, depending on degree of
8-20 mg/kg/d PO as hydrochloride and 8-25 mg/kg/d as
palmitate divided tid/qid 20-40 mg/kg/d IV/IM divided
Metronidazole (Flagyl)
Imidazole ring-based antibiotic active against various
anaerobic bacteria and protozoa. Used in combination with
other antimicrobial agents (except for Clostridium
difficile enterocolitis).
Loading dose: 15 mg/kg or 1 g for 70-kg adult IV over 1 h
Maintenance dose: 6 h following loading dose; infuse 7.5
mg/kg or 500 mg IV for 70-kg adult over 1 h q6-8h; not to
exceed 4 g/d
15-30 mg/kg/d PO divided bid/tid for 7 d, or 40 mg/kg once;
do not exceed 2 g/d
Antifungal agents
Their mechanism of action may involve an alteration of RNA
and DNA metabolism or an intracellular accumulation of
peroxide that is toxic to the fungal cell.
Amphotericin B (AmBisome)
Produced by a strain of Streptomyces nodosus; can be
fungistatic or fungicidal. Binds to sterols, such as ergosterol,
in the fungal-cell membrane, causing intracellular
components to leak with subsequent fungal-cell death.
3-5 mg/kg/d IV of liposomal amphotericin B over
approximately 120 min
Administer as in adults
Fluconazole (Diflucan)
Synthetic oral antifungal (broad-spectrum bistriazole) that
selectively inhibits fungal cytochrome P-450 and sterol C-14
150 mg PO once or 400 mg/d, depending on severity of
3-6 mg/kg/d PO for 14-28 d or 6-12 mg/kg/d, depending on
severity of infection
Further Inpatient Care
1. Aggressively seek an underlying source of the abdominal
2. Perform weekly serial CT scans or ultrasound
examinations to document adequate drainage of abscess
3. Maintain drains until the output is less than 10 cc/d.
4. Monitor fever curves. Persistent fever after 2 weeks of
therapy may indicate the need for more aggressive
For patients with an underlying malignancy, definitive
treatment, such as surgical removal of the mass, should
be pursued if at all possible.
Further Outpatient Care
1. Patients will require prolonged parenteral antimicrobial
therapy that may continue after discharge. Monitoring of
medication levels, renal function, and blood counts may
be needed. Enteral nutrition is the preferred route
unless it is clinically contraindicated.
2. Drain care may be required.
3. Continue radiologic evaluation to document progress of
therapy after discharge.
1. Sepsis
2. Empyema resulting from contiguous spread or
intrapleural rupture of abscess
3. Rupture of abscess with resulting peritonitis
4. Endophthalmitis when an abscess is associated with K
pneumoniae bacteremia
1. If a liver abscess is left untreated, the prognosis is
uniformly fatal.
2. Indicators of a poor prognosis have been described since
1938 and include multiplicity of abscesses, underlying
malignancy, severity of underlying medical conditions,
presence of complications, and delay in diagnosis.2
3. Indicators of a poor prognosis in amebic abscess include
a bilirubin level of greater than 3.5 mg/dL,
encephalopathy, hypoalbuminemia (ie, serum albumin
level of <2 g/dL), and multiple abscesses; all are
independent factors that predict poor outcome.
4. An underlying malignant etiology and an Acute
Physiology and Chronic Health Evaluation (APACHE II)
score greater than 9 increases the relative mortality by
6.3-fold and 6.8-fold, respectively.
5. Chen et al examined prognostic factors for elderly
patients with pyogenic liver abscess. 4 Results from the
study, which included 118 patients aged 65 years or
older and 221 patients below age 65 years, indicated
that age and an APACHE II score of 15 or greater at
hospital admission were risk factors for mortality. The
evidence ultimately suggested that outcomes for older
patients with pyogenic liver abscess are on a par with
those for younger patients. The investigators also found
that in the younger patient group, there was greater
frequency of males suffering from alcoholism, a
cryptogenic abscess, and K pneumoniae infection.

Liver Abscess - Dis Lair