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Discussion on Liver Abscess
Muhamad Na’im B. Ab Razak
University Sains Malaysia
64 Years old Malay gentleman with no known medical illness works as trishaw driver presented
to A&E department because of progressive abdominal pain and discomfort mainly at right
hypochondriac region since 1 month ago, fever of unknown origin, poor oral intake, yellowish
discoloration of eyes and constipation. Before the abdominal discomfort starts, he has history of
spurious diarrhea. Examination reveals tender hepatomegally. Abdominal ultrasound reveals
heterogeneous hyperechoic lesion seen at the subcapsular region in the posterior segment
(segment VI, VII) of liver with irregular margin, measuring 8.0cm x 4.0cm. Abdominal CT scan
shows Ill-defined irregular defined hypodense non enhancing lesion at the segment of the liver
measuring 3.7cm with an irregularity of the wall of the lesion and continuous with the
subcapsular fluid collection that is extending into the perihepatic region. He was treated with US
guide percutaneous aspiration and covered with IV Metronidazole and IV Cefobid.
Abscess is defined as a circumscribed collection of purulent exudates appearing in an acute or
chronic localized infection, caused by tissue destruction and frequently associated with swelling
and other signs of inflammation. [Stedman’s]
Abscess formation is associated with significant morbidity and mortality, despite the availability
of potent antibiotics. Un-drained abscesses result in a mortality rate of 50–80% (Gravis and
Dawson 2006) [Mahnken&Ricke]. Liver abscesses made up 13% of the total number of
abscesses or 48% of all visceral abscesses.
The liver abscess is classified mainly into pyogenic and amebic types. However, currently liver
abscess due to fungal infection has also been added to classification. Since fungal liver abscess
is extremely rare and occurring in patient with impaired body immune response, it is not being
discussed in this writing. Another rare cause of liver abscess that has been reported in
literature is liver abscess secondary to foreign body, for example; needle that migrates to liver
from perforation of gut at ileocecal junction and recto sigmoid region. It is also noted that
Diabetes Mellitus is a major predisposing factors for liver abscess throughout the world
Pyogenic liver abscess is uncommon, accounting for 8 to 25 cases per 100,000 hospital
admissions. Over the past 2 decades, its case fatality rate was around 11.5 to 40%. E. coli and K.
pneumonia are by far the most common isolates in pyogenic liver abscess and Gas Forming
Pyogenic Liver Abscess has a high percentage of K. pneumoniae [Hsin-Ling Lee]
There is also a reported case of nasocomial pyogenic liver abscess caused by Extended-
Spectrum Beta-Lactamase-Producing Klebsiella pneumonia after intensive chemotherapy for
carcinoma of the stomach and prolonged antibiotic treatment for recurrent bacteremia.
Amoebic liver abscess although rare compared to Pyogenic liver abscess, the prevalence is still
high especially in a develop country and associated with poor hygiene and poverty.
The causative agent is mainly Entamoeba histolytica. The infection causes by this organism has
caused death for approximately 40 000 to 100 000 people annually due to various complication.
Therefore, it is crucial to treat this disease as early as possible.
Amebic liver abscess is caused by hematogenous spread of the invasive trophozoites. This
complication is seen mainly in young males between 18 and 50 years of age. Diagnosis depends
on clinical findings, ultrasound or radiographic imaging techniques, and, especially, also on
serological studies. [H. Rogier van Doorn]
The problem with infection of E. histolytica is, most of the patient is asymptomatic. Only 4- 10%
infected patient develop amoebic disease within a year with amebic abscess and colitis being
the most important clinical entities.
The infection starts with an ingestion of amebic cysts, which, after excystation form
trophozoites in the small intestine, colonize the bowel lumen and invade the intestinal
epithelium resulting in amebic colitis [Viroj Wiwanitkit], and cause symptoms such as
abdominal pain, tenderness, (bloody) diarrhea, and weight loss. The presence of erythrocytes in
hematophagous trophozoites of E. histolytica in freshly passed stools is pathognomonic for
amebic colitis. An antibody response against E. histolytica arises in a large proportion of these
patients [H. Rogier van Doorn]
Clinically, it is hard to differentiate whether the abscess is caused either by pyogenic or
amoebic organism. Most of the patient presented with fever, abdominal pain especially right
hypochondriac region, weight loss, anorexia, nausea and vomiting, tender hepatomegally and
some of them might present with symptoms of respiratory system.
Full blood count usually shows Leukocytosis. Blood cultures and sensitivities are also useful
especially in pyogenic liver abscess. Liver function test are normal in most patient but some of
them may have elevated alkaline phosphates level.
In establishing E. hystolytica as causative agents, serological test may be done by using ELISA,
Dipstick, and Latex Agglutination Test. The specificities of these tests were 97.1%, 98.1%, and
99.5%, respectively and all modalities shows sensitivity of 93.3%.
The present study for the first time shows that the kidney barrier in ALA patients is permeable
to E. histolytica DNA molecule resulting in excretion of E. histolytica DNA in urine which can be
detected by PCR. The study also shows that the PCR for detection of E. histolytica DNA in urine
of patients with ALA can also be used as a prognostic marker to assess the course of the
diseases following therapy by metronidazole. The detection of E. histolytica DNA in urine
specimen of ALA patients provides a new approach for the diagnosis of ALA. [Subhash C Parija]
Ultrasonogram is an easy, widely available non-invasive and dependable investigation in
diagnosing liver abscess. It will usually show an area of hypoechoiec lesion surrounded by
edematous tissue and some of them show hyperechoic surrounding.
By CT scan, typically it will show a lesion in right liver lobe with average size of 4.5 cm; round or
sub-round in shape, uninterrupted and sharp edges, low attenuation of less than 20 Houston
units, and some of them may have a rim-shaped enhancement lesion. Other findings may
include honeycomb-like, grid like or strip like enhancement. Lesion on the left lobe usually
associated with increased risk of rupture. Atypical findings may warrant a further investigation
to exclude malignancy.
Both ultrasound and CT scan also could not differentiate either the abscess is caused by
pyogenic or amoebic bacteria.
Besides serology test, another way to differentiate this two entity is by culture and sensitivity of
the pus drained from the abscess. Usually, pyogenic organism may yield positive culture while
amoebic organism may show sterile culture.
Based on ultrasound, liver abscess may be classified according to its size into three type which
are 1) Abscess Type I (small <3 cm), 2) Abscess Type II (large >3 cm, unilocular), and 3) Abscess
Type III (large >3 cm, complex multilocular)
The advanced in diagnostic and therapeutic radiology; CT scan and Ultrasound for the past two
decades has greatly changed the treatment of choice in treating liver abscess. Percutaneous
needle aspiration and catheter drainage now, are the first choice of treatment, replacing the
role of open surgery.
For a small abscess, intravenous antibiotic is a first line treatment. The combination of
Metronidazole and second generation cephalosporin usually yield a good cure rate.
Hsiao-Pei Cheng in his study says that if the aetiology is due to Klabsiella pneumoniae, the
organism remains susceptible to cefazolin. However the antibiotic did not give optimal
treatment for the disease, have higher rate for concomitant use of an aminoglycoside and
higher rate of development of severe complications. In a comparative study with extended
spectrum cephalosporin, he draws a conclusion that an extended-spectrum cephalosporin is
better than cefazolin for the treatment of liver abscess due to K. pneumoniae.
If the abscess is > than 5 cm, therefore drainage is necessary in facilitating the resolution of the
abscess. Drainage of as much pus as possible will also give better result of antibiotic action.
Percutaneous abscess drainage is a minimally invasive intervention performed under local
anesthesia with success rates, morbidity, and mortality as good as or better than those of
surgery. Complications are rare and mostly refer to pain and catheter dislodgement. In
combination with surgery, the extent of subsequent surgery is reduced and one-stage
procedures become possible. [Mahnken&Ricke]
While, percutaneous drainage is the best surgical management for liver abscess, open surgical
drainage is indicated in cases of rupture, multiloculation, associated biliary or intra-abdominal
Percutaneous drainage prior to open surgical drainage may optimize the clinical condition of
the patient prior to surgery
A retrospective study for 15 years by Strong R et al have found that there are two indications
for operation in liver abscess (Pyogenic) with hepatectomy which are failed non- operative
treatment (76%) and underlying hepatobiliary pathology (20%). only two of them suffered
complication of peritonitis secondary to ruptured liver abscess.
Ng SS, et all found that mortality rate in patient requiring conventional surgery due to various
reason is high with overall mortality of 46% either due to multi organ failure or pulmonary
Apart from that, many studies have been done to look for the best and optimize way in treating
liver abscess. One of them is by Hope WW who develops the algorithm of treatment of liver
abscess based on size.
Based on his findings, the algorithm is as follow, 1) small abscesses being treated with
antibiotics alone; 2) large, uniloculated abscess with percutaneous drainage plus antibiotics;
and 3) large, multiloculated abscessed treated with surgical therapy.
The complication of liver abscess include recurrence, pleuro-peritoneal involvement and
rupture of the abscess
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