Discussion on Liver Abscess

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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.

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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>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

Reference

1) Andreas H. Mahnken and Jens Ricke, "CT- and MR-Guided Interventions in Radiology", p.125-149, Springer Berlin Heidelberg, 2009

2) Cheng-Lin Wang, Xue-Jun Guo, Shui-Bo Qiu,et al "Diagnosis of bacterial hepatic abscess by CT", Hepatobiliary Pancreat Dis Int 2007; 6: 271-275

3) Chintamani, Vinay Singhal, Parminder Lubhana, et al, "Liver abscess secondary to a broken needle migration- A case report", BMC Surgery , 3:8, BioMed Central Ltd, 2003

4) Chung YF, Tan YM, Lui HF et al, "Management of pyogenic liver abscesses - percutaneous or open drainage?", Singapore Med J. 2007 Dec;48(12):1158-65

5) Hope WW, Vrochides DV, Newcomb WL, et al, "Optimal treatment of hepatic abscess." Am Surg. 2008 Feb;74(2):178-82

6) Hsiao-Pei Cheng, L. K. Siu& Feng-Yee Chang, "Extended-Spectrum Cephalosporin Compared to Cefazolin for Treatment of Klebsiella pneumoniae-Caused Liver Abscess", Antimicrobial Agents and Chemotherapy, July, p. 2088–2092, American Society for Microbiology, 2003

7) Hsin-Ling Lee, Hsin-Chun Lee, How-Ran Guo et al, "Clinical Significance and Mechanism of Gas Formation of Pyogenic Liver Abscess Due to Klebsiella pneumoniae", Journal Of Clinical Microbiology, June, p. 2783–2785, American Society for Microbiology 2004

8) Jung-Chung Lin, L. K. Siu,, Chang-Phone Fung et al, "Nosocomial Liver Abscess Caused by Extended Spectrum Beta-Lactamase-Producing Klebsiella pneumoniae, Journal Of Clinical Microbiology, Jan, p. 266–269, American Society for Microbiology, 2007.

9) M N Alom Siddiqui, M Abdul Ahad, A R M Saifuddin Ekram et al, "Clinico-Pathological Profile of Liver Abscess in a Teaching Hospital", The Journal of Teachers Association RMC, June; Volume 21 Number 1, 2008.

10) Ng SS, Lee JF, Lai PB., "Role and outcome of conventional surgery in the treatment of pyogenic liver abscess in the modern era of minimally invasive therapy.” World J Gastroenterol. 2008 Feb 7;14(5):747-51

11) Strong R, Fawcett J, Lynch S, Wall D, "Hepatectomy for pyogenic liver abscess", HPB (Oxford). 2003;5(2):86-90.

12) Subhash C Parija & Krishna Khairnar, "Detection of excretory Entamoeba histolytica DNA in the urine, and detection of E. histolytica DNA and lectin antigen in the liver abscess pus for the diagnosis of amoebic liver abscess, BMC Microbiology 2007, 7:41, BioMed Central Ltd

13) Viroj Wiwanitkit, "A note on clinical presentations of amebic liver abscess: an overview from 62 Thai patients", BMC Family Practice, 3:13, BioMed Central Ltd, 2002