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

pathology.

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

embolism.

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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