Liver Abscesses Types, Clinical Features, Investigations

Enumerate the types, etiopathogenesis, clinical features, investigations and principles in the management of liver abscess. Also differences between the types of liver abscesses.

Pyogenic Liver Abscess

Pyogenic Liver Abscess Causes

1. Infection through the portal vein
   • Acute appendicitis
   • Acute diverticulitis (sigmoid)
   • Acute amoebic colitis
   • Acute bacillary dysentery
   • Ulcerative colitis
2. Infection through the common bile duct (CBD)
   • Stricture of the CBD
   • Periampullary carcinoma resulting in stasis of the bile, precipitating infection (cholangitis)
   • Recurrent cholangitis due to stone in the CBD
   • ERCP
3. Infection through the hepatic artery
   • Septicaemia and pyaemia
   • Actinomycosis of faciocervical region
4. Extension abscess
   • Subdiaphragmatic abscess
   • Empyema thoracic
   • Penetrating injuries
5. Infection through umbilicus: Neonatal umbilical sepsis giving rise to pyaemia.

Pyogenic Liver Abscess Certain Facts

• The majority of the infective bacteria are derived from the gastrointestinal tract.
• In the majority of cases, it is a polymicrobial infection.
• E. coli is the most common facultative organism.
• Bacteroides fragilis is the most common anaerobe.
• Candidal infection is increasing due to chemotherapy, especially for leukaemic patients.

Pyogenic Liver Abscess Bacteriology

1. Anaerobic bacteria: 60% (Bacteroides fragilis)
2. Enteric gram –ve bacteria
   • Escherichia coli: 40%
   • Klebsiella pneumoniae: 10–20%
3. Others: 4–40%
4. Gram +ve bacteria
   • Staphylococcus aureus : 4–25%

Pyogenic Liver Abscess Clinical Features

• Alcoholic males and debilitated men suffer more, probably because of poor immunity.
• Acute abscesses are usually multiple, chronic abscesses are single.
• Tender hepatomegaly and low-grade or high-grade pyrexia with abdominal discomfort are the main features.

Pyogenic Liver Abscess Investigations

• Total WBC count is raised.
• Stool routine examination: Amoebic cysts, culture and sensitivity for typhoid bacilli.
• Abdominal ultrasound and ultrasound-guided aspiration establishes the diagnosis.
• When in doubt, CT scan can be done, followed by FNAC which draws frank pus. Pus is sent for Gram’s stain, culture and sensitivity. CT also helps in the diagnosis of associated conditions such as diverticulitis of the colon.
• Further investigations are directed towards the associated conditions. Examples:
  • Chest X-ray: Air under the diaphragm (perforation of hollow viscus) or diagnosis of empyema thoracic.

Pyogenic Liver Abscess Treatment

1. Conservative: Multiple small abscesses may respond to antibiotics. However, they have to be given for 4 to 6 weeks.
2. Percutaneous drainage – Method
   • Ultrasound or CT-guided aspiration and drainage by using a pigtail catheter.
   • Irrigation of abscess cavity with saline.
3. Open (surgical) method: Laparotomy is required mainly to treat the primary causes, for example, appendicectomy, and drainage of the appendicular abscess. If the liver shows a significant abscess, it is drained. Alternately, a pigtail catheter is introduced into the abscess cavity and brought outside through a separate opening. It helps to drain for a longer period of time.
4. Laparoscopic drainage can also be done.

• Percutaneous Drainage – Indications
  • Superficial abscesses
  • Abscess with no intra-abdominal pathology
  • Abscess of unknown aetiology
• Open (Surgical) Method- Indications
  • Abscess with intra-abdominal pathology
  • Ascites
  • Deep-seated abscess
  • Multiple abscesses

Amoebic Liver Abscess

It is also called a tropical abscess (dysenteric abscess). It is the most common extraintestinal manifestation of amoebiasis.

Aetiopathogenesis

• This disease is caused by Entamoeba histolytica.
• It is almost always a complication of amoebic dysentery. This can occur in the acute stage or in the chronic carrier stage.
  • Infection from the caecum (typhlitis) spreads through the tributary of the superior mesenteric vein.
  • From the sigmoid colon, through the tributary of the inferior mesenteric vein.
• The right branch of the portal vein is in direct line with the portal vein. Hence, by streamlining the phenomenon organisms reach the right lobe more often than the left lobe. The right lobe is also much bigger than the left lobe.
• In the right lobe, it is the posterosuperior surface which gets involved because it is extraperitoneal (bare area of liver). It has no peritoneal covering.
• After reaching the liver, the organism causes the destruction of hepatocytes by releasing powerful cytolytic enzymes resulting in liquefaction necrosis. It also causes aseptic thrombosis of blood vessels resulting in necrosis of liver tissue.
• At the same time, some RBCs are also broken down. This causes anchovy sauce pus, which is chocolate brown in colour and is a mixture of broken-down RBCs, hepatocytes, etc.
• Green pus is referred to as pus mixed with bile, which is seen in a few patients.
• In majority of the cases, pus is sterile. Secondary infection occurs in about 20 to 30% of the cases.
  Amoebae are rarely present in the pus but are present in the wall of the abscess cavity. The wall contains monocytes, plasma cells, lymphocytes and fibroblasts.
• Abscesses are multiple which fuse to form a single large abscess cavity in about 70% of the cases. Due to perihepatitis, the abscess gets fixed to the diaphragm resulting in the immobility of the diaphragm. Liver abscess in the left lobe gets adhered to the anterior abdominal wall.
• It is interesting to note that amoebic infection of gallbladder and bile does not occur because of the deleterious effect of bile on amoebae.

Amoebic Liver Abscess Clinical Features

• Male alcoholics are commonly affected, in the age group of 20-40 years. It is eight times more common in men.
• Seen in patients with low socioeconomic status.
• Severe pain in the right hypochondrium is due to the enlarged liver. This stage is called stage of amoebic hepatitis. If USG is done, it may not demonstrate any abscesses but there may be many microabscesses. At this stage, there is a low-grade fever, weakness, anorexia, etc.
• High-grade fever with chills and rigours develop if the stage proceeds to pyogenic liver abscess due to secondary bacterial infection of amoebic abscess.
• Thoracic symptoms such as nonproductive cough, pleurisy and right shoulder pain are common.

Amoebic Liver Abscess Signs

• Anaemia, emaciation, toxic look and an earthy complexion are present.
• Jaundice may be present, if abscesses are multiple, due to compression of biliary radicles. However, it is rare (15%).
• It is of cholestatic variety.
• Liver is enlarged in the right hypochondrium, tender and soft (liver enlarges in upward direction).
• Intercostal tenderness differentiates it from acute cholecystitis. Intercostal oedema can also be present.
• Very Tender Liver
  • Amoebic liver abscess
  • Hepatoma
  • Congestive cardiac failure

Liver Clinical Features:

Amoebic Liver Abscess Investigations

1. Total WBC count may be increased, if there is a secondary infection.
2. Stool examination for ova and cysts of Entamoeba histolytica may be positive in 25% of cases.
3. Serologic testing: The indirect haemagglutination test is positive in 90-95% of patients with an amoebic abscess.
4. Screening chest: When the patient is asked to take a deep breath, the right side of the diaphragm does not move due to inflammatory (perihepatitis) adhesions between liver and the diaphragm. This is called homo-lateral immobility of the diaphragm. A small pleural effusion may also be present.
5. Sigmoidoscopy may demonstrate large, deep amoebic ulcers—flask-shaped.
6. Abdominal USG: It is the investigation of choice.
   • To locate site of abscess and then to confirm the diagnosis.
   • Ultrasound-guided needle aspiration can also be done and biopsy of the abscess wall should be taken.
     Multiple abscesses can be made out.
7. CT scan can demonstrate an abscess cavity as a low-density zone surrounded by a peripheral hypodense zone due to an inflammatory reaction.

Amoebic Liver Abscess Treatment: It can be classified into

1. Conservative
2. Ultrasound-guided aspiration and pigtail drainage
3. Surgery—drainage

1. Conservative Line of Management

• It is indicated in amoebic hepatitis. Tab. metronidazole 400-800 mg 3 times a day is given for 14 days. The only recognisable side-effect is metallic taste.
• If the condition does not improve, injection emetine 1 mg/kg body weight to a total of 60 mg/day deep IM for a maximum of 6 days is given.
• Side-effects and Precautions during Emetine Therapy
  • Systolic BP should be at least 100 mmHg.
  • ECG should be recorded before, during and after the therapy.
  • Cardiotoxicity in the form of arrhythmias can occur.
  • Absolute bed rest during treatment (because of these complications, it is not used nowadays).
  • Adequate hydration, rest, and analgesics to relieve the pain.
  • Improvement can be seen within one to two days in the form of disappearance of pain, fever and return of appetite.

2. US-guided Needle Aspiration/Pigtail Catheter Drainage

• It is indicated in cases of amoebic liver abscess.
• Before it is aspirated, the bleeding profile (BT, CT, PT) should be normal and injection vitamin K 10 mg, IM should be given for at least 3 days.
• US-guided aspiration is also the treatment of choice where metronidazole is contraindicated, e.g. 1st trimester of pregnancy.
• It can be easily done under local anaesthesia.
• Can be repeated, if pus recollects. Typically, it is anchovy sauce pus. Aspiration is followed by the insertion of a pigtail catheter.
• They are the catheter used to drain clear fluids from cavities such as pleural fluid, ascites, bile, etc.
• Different sizes are available 8 to 12 French
• Radio-opaque polyurethane catheter
• Length—20 or 30 cm
• Large oval holes in pigtail for maximum drainage
• Thus, maximum efficiency is when ‘transudate’ pleural effusion is drained, than empyema, haemothorax or anchovy sauce pus
• Before removal of the catheter do a repeat ultrasound to check for residual pus.
• The clinical response to the aspiration may be observed as subsiding of fever.

US-guided Needle Aspiration/Pigtail Catheter Drainage Complications

1. Bleeding—rare
2. Incomplete aspiration results in leakage of pus and bile into peritoneal cavity which may produce peritonitis. Hence, prophylactic antibiotics need to be given before and after the procedure along with metronidazole therapy.

3. Surgery (Open Drainage) and Laparoscopic

• Surgery and Laparoscopic Indications
  1. Failure of US-guided needle aspiration.
  2. Ruptured amoebic liver abscess with amoebic peritonitis.
• Surgery and Laparoscopic Procedure
  • Laparotomy is done first. Abscess cavity is identified. Contents are evacuated, a thorough peritoneal wash is given and a self-retaining Malecot’s catheter (any tube drain) is introduced into the abscess cavity, brought outside and connected to a bag.
  • With the advent of metronidazole, amoebiasis cutis is rarely seen. Hence, the catheter can be safely placed inside the cavity and brought out. Malecot’s catheter is now being replaced by other tube drains.
  • Postoperatively for 3-5 days, necrotic liver tissue, anchovy sauce pus and blood drain outside.
  • Once the drainage becomes minimal, Malecot’s catheter is pulled out.
  • Same procedure can be done by laparoscopic method.
• Surgery and Laparoscopic Complications
  • Amoebic peritonitis, resulting in acute abdomen with shock. It has to be treated like any peritonitis— laparotomy, drainage of pus and drain the abscess cavity to the outside (the possibility of amoebiasis cutis is still present but rare).
    Rupture into pleural space causing pleural effusion.
  • Rupture into the bronchus resulting in coughing out anchovy sauce (maybe a natural cure)—broncho-pleural fistula.
  • Amoebic pericardial effusion occurs due to rupture of left liver lobe abscess into pericardial space.