Pyogenic Liver Abscess : Pathology, Diagnosis, Treatment

Introduction of Pyogenic Liver Abscess

The liver is the most common site of abdominal visceral abscess. Pyogenic liver abscess is the most common type of liver abscess. It is more common in males and is seen at 50-60 years of age. Most patients with pyogenic liver abscesses have biliary tract disease or cryptogenic abscesses (the cause is not known). Certain co-morbid conditions are associated with pyogenic liver abscesses, such as liver Cirrhosis, diabetes mellitus, Chronic renal failure, and a History of malignant disease.

Pathogenesis of Pyogenic Liver Abscess

The most common route of infection is the biliary tract. The second most common route is the portal vein, and the third most common route is the hepatic artery.

In certain cases, there is a direct extension of infectious.

In biliary tract obstruction, the cause of obstruction in the majority of cases is stone or malignancy, especially cholangiocarcinoma. Due to this, there is stasis and an increased risk of infection. Further Infection spreads and is called ascending suppurative cholangitis.

The patients can have CBD stones, which can cause Recurrent Pyrogenic Cholangiocarcinoma (RPC). In RPC, the patients have intrahepatic biliary strictures, and there is an increased risk of cholangitis in the Asian population and cholangiocarcinoma in Western countries.

The portal vein is the second most common root of infection. It drains the GI tract, so whenever there is any infective disorder of the GI tract, there is ascending portal venous infection, which is also known as Phlebitis.

Previously, untreated appendicitis was considered the most common cause of pyogenic liver abscess. Because of the availability of good antibiotics and early detection, it is not the most common cause anymore.

The hepatic artery is the third most common route of infection. Patients have a systemic infection that causes bacteremia. This bacteria reaches the liver via the hepatic artery and causes a pyogenic liver abscess. This is especially seen in patients with Endocarditis, Pneumonia, and Osteomyelitis. This route is important because there is an increased risk of pyogenic liver abscesses via this route in patients who are immunocompromised, like AIDS, and children suffering from chronic granulomatous disease, which is a disorder of granulocyte function.

Pathology and Microbiology of Pyogenic Liver Abscess

In the majority of patients with pyogenic liver abscess, the right liver is involved due to preferential laminar blood flow to the right side. The left lobe is involved in 25% of patients. The involvement of the caudate lobe is rare and seen in 5% of patients. Some of the patients have bi-lobar involvement with multiple abscesses, but this kind of presentation is uncommon.

Whenever the abscess results from Pylophlebitis or cholangitis when the biliary tract and portal veins are the routes, it is polymicrobial. If the abscess results from systemic infections via the hepatic artery, it is monomicrobial.

In polymicrobial infection, the most common organism responsible is E.coli, followed by Klebsiella. In children suffering from chronic granulomatous disease, the abscess occurs via the hepatic artery, and the organism responsible is Staph aureus. The organism responsible for gas-forming abscesses is Klebsiella. The fungal and mycobacterial causes leading to hepatic abscesses are rare.

Clinical Features of Pyogenic Liver Abscess

In a Pyogenic liver Abscess, there is a pus-filled cavity in the liver. The patient will have a fever with chills. This is the most common symptom, followed by abdominal pain.

In the majority of cases, the cavity is single and involves the right lobe. If the biliary tract, which is the most common route, is involved, there is obstruction. So, the most common LFT abnormality is the raised ALP. The classic presentation is where the patient has fever, jaundice, right upper quadrant pain, and tenderness, which is seen only in 10% of patients.

If the diaphragm is involved in pyogenic liver abscess, the patient will have cough and dyspnea.

Endogenous endophthalmitis is classically associated with Klebsiella infections. Klebsiella hepatic abscess is also associated with this condition. It is a rare condition seen in only 3% of patients, but it is common in patients with diabetes mellitus. Early diagnosis and treatment will give the best chance to preserve visual functions.

Examination of Pyogenic Liver Abscess

The most common finding is fever, and There is tenderness in the right upper quadrant. Jaundice is seen in 25% of patients, hepatomegaly in 50% of patients, and chest findings are positive in 25% of patients.

Lab Changes in Pyogenic Liver Abscess

ALP is raised in 80% of patients. Since the patient has jaundice, total bilirubin is raised in 20-50% of patients.

Diagnosis of Pyogenic Liver Abscess

The main diagnostic modalities are ultrasonography and CT scan. The diagnosis is confirmed by aspiration and culture. If a chest x-ray is done, it is abnormal in 50% of cases.

The findings on the chest X-ray are elevated right hemi diaphragm, right-sided pleural effusion, and collapse of the ipsilateral lung, known as Atelectasis.

The same findings are also seen in patients with amoebic liver abscesses.

Treatment and Management of Pyogenic Liver Abscess

The treatment of choice in case of pyogenic liver abscess is percutaneous catheter drainage. IV antibiotics are also given for 2 weeks and then switched to oral. Till culture is available, 

Ampicillin is given, which will cover gram-positive, Aminoglycosides will cover gram-negative and Either Metronidazole or 3^rd generation Cephalosporin for abscess caused by anaerobes.

Relative Contraindication for pPercutaneous CatheterDrainage in Pyogenic Liver Abscess

• Ascites
• Coagulopathy
• Proximity to the vital structures

Indications Of Surgery In Pyogenic Liver Abscess

• Patients requiring surgical treatment for pathologic process – if the patient is already having appendicitis, appendectomy is done and simultaneously pyogenic liver abscess is treated.
• If the patient fails to respond to the percutaneous technique.

Also Read: Biliary Tree Pathophysiology & Investigations

Indications Of Hepatic Resection In Pyogenic Liver Abscess

• If the patient is having infected hepatic malignant neoplasm.
• Patients having Hepatolithiasis
• Patients having intrahepatic biliary strictures.
• Severe hepatic destruction because of infections.

Prognosis of Pyogenic Liver Abscess

• If the patient is having pyogenic liver abscess, simultaneously, the patient will also have Malignant disease, Jaundice, Sepsis, Hypoalbuminemia, Abscess rupture and Shock. In all these cases, there is poor prognosis and these patients have increased mortality.

Frequently asked questions

1) Is jaundice common or rare in patients of Pyogenic Liver Abscess?

Ans: It is common and seen in 25% patients.

2) What is the most common LFT abnormality in patients of Pyogenic Liver Abscess?

Ans: Raised ALP

3) What is the most common route of infection in Pyogenic Liver Abscess?

Ans: Biliary tract

4) What is the second most common route of infection in Pyogenic Liver Abscess?

Ans: Portal vein

5) What is the third most common route of infection in pyogenic liver abscess?

Ans: Hepatic artery

6) Why is right hemi liver most commonly involved?

Ans: Because there is preferential laminar blood flow to the right side.

7) Which organism is responsible for gas forming abscess?

Ans: Klebsiella

8) Which is the most common organism responsible for pyogenic liver abscess overall?

Ans:  E.coli

9) Which is the most common organism responsible for pyogenic liver abscess in Asian populatin?

Ans: Klebsiella

10) Which is the most common organism responsible for pyogenic liver abscess in children suffering from granulomatous disease?

Ans: Staph aureus

11) In what % of patients there is jaundice?

Ans: 25%

12) What is the treatment of choice for pyogenic liver abscesses?

Ans: Percutaneous cathedral drainage

Also Read: Colorectal Polyps : Types, Neoplastic Polyps