Amoebic Liver Abscess Flashcards
What organism is responsible for Amoebic Liver Abscess (ALA)?
The organism responsible for Amoebic Liver Abscess (ALA) is Entamoeba histolytica, a protozoan parasite.
How common is Amoebic Liver Abscess (ALA) globally?
Amoebic Liver Abscess (ALA) is an uncommon but potentially life-threatening complication of Entamoeba histolytica infection, causing up to 40 million infections annually and leading to 100,000 to 400,000 deaths from intestinal and extra-intestinal amoebiasis.
Is South Africa considered an endemic area for Amoebic Liver Abscess (ALA)?
South Africa is not considered an endemic area for Amoebic Liver Abscess (ALA), but cases have been treated at local hospitals, such as the “Red Cross Children’s Hospital.”
How is Entamoeba histolytica transmitted?
Entamoeba histolytica is transmitted via the fecal-oral route.
Where does Entamoeba histolytica typically establish itself in the body?
Entamoeba histolytica typically establishes itself in the colon, where it invades the mucosa, causing ulceration and colitis. It can then spread to distant extra-intestinal sites, with the liver being the most common site.
How common is Amoebic Liver Abscess (ALA) in patients with amoebic infection?
Amoebic Liver Abscess (ALA) occurs in approximately 5-7% of patients who develop amoebic infestation of the intestinal tract.
Which age group is most affected by Amoebic Liver Abscess (ALA)?
Amoebic Liver Abscess (ALA) is more common in adults, but it also occurs in children, although reports on pediatric cases are sporadic.
What is the second most common form of invasive amoebiasis?
After amoebic dysentery, amoebic liver abscess is the second most common form of invasive amoebiasis caused by Entamoeba histolytica.
What percentage of children and adults with invasive intestinal amoebiasis develop Amoebic Liver Abscess (ALA)?
Amoebic Liver Abscess (ALA) occurs in 1-5% of children and 10-50% of adults with invasive intestinal amoebiasis.
How does Entamoeba histolytica begin its life cycle?
The life cycle of Entamoeba histolytica begins when a person ingests cysts from contaminated food or water, typically through the fecal-oral route
What happens to the cysts once they are ingested by a host?
Once ingested, the cysts pass through the stomach and into the small intestine, where they excyst (break open) and release trophozoites (the active form of the parasite).
What do trophozoites do after excysting in the intestine?
After excysting, trophozoites travel to the large intestine, where they adhere to the mucosal lining and can invade the intestinal wall, leading to ulceration and amoebic colitis. Some trophozoites also disseminate to other organs, such as the liver, causing an abscess.
How are cysts formed in the life cycle of Entamoeba histolytica
Trophozoites in the large intestine can encyst, forming cysts that are excreted in the host’s stool. These cysts are the infectious form of the parasite.
How do cysts of Entamoeba histolytica spread the infection?
Cysts excreted in the stool contaminate the environment, including food, water, or surfaces, and can be ingested by a new host, thus completing the life cycle of Entamoeba histolytica.
What is the role of the liver in the life cycle of Entamoeba histolytica?
The liver can be a site for extra-intestinal infection. Trophozoites that invade the intestinal wall may spread through the bloodstream to the liver, where they can form abscesses, leading to Amoebic Liver Abscess (ALA).
How does Entamoeba histolytica cause systemic infection?
Entamoeba histolytica causes systemic infection when trophozoites break away from the intestine and enter the bloodstream, spreading to other organs such as the liver, lungs, and brain.
What is the relevance of understanding the life cycle of Entamoeba histolytica in the diagnosis of Amoebic Liver Abscess (ALA)?
What is the relevance of understanding the life cycle of Entamoeba histolytica in the diagnosis of Amoebic Liver Abscess (ALA)?
How is amoebiasis diagnosed in South Africa?
Since amoebiasis is not endemic in South Africa, the diagnosis is often made after excluding other causes of dysentery, abdominal pain, and fever. Amoebiasis should still be kept in the differential diagnosis for all children with diarrhoeal illness, dysentery, and abdominal pain.
What are the most common symptoms of Amoebic Liver Abscess (ALA)?
The most common symptoms of ALA include:
Right upper quadrant pain
High fever (virtually present in all cases)
What symptoms are less common in Amoebic Liver Abscess (ALA)?
Less common symptoms include:
-Anorexia and vomiting (present in less than 30% of cases)
- A history of dysentery, which is also uncommon
What signs are typically observed in the clinical examination of a patient with Amoebic Liver Abscess (ALA)?
Signs often observed include:
- Right upper quadrant pain and point tenderness over the liver
- Abdominal distension
- Hepatomegaly (enlarged liver)
- Oedema of the anterior abdominal wall, particularly in the right upper quadrant
What is a key finding during the clinical examination of the liver in ALA?
On careful examination, the liver is often exquisitely tender, and the point of most tenderness is very specific, helping to localize the infection.
How does a travel history assist in the diagnosis of Amoebic Liver Abscess (ALA)?
If a patient presents with a very high fever, right upper quadrant pain, specific tenderness, and a relevant travel history (to endemic areas), the diagnosis of ALA is almost certain.
What are the main complications of Amoebic Liver Abscess (ALA)?
As the abscess enlarges, it can rupture into:
- The peritoneal cavity
- The pleural space
- The pericardium
In each case, symptoms will be related to the body cavity or organ involved.
What happens if an Amoebic Liver Abscess (ALA) ruptures into the peritoneal cavity?
If the abscess ruptures into the peritoneal cavity, the patient may experience peritonitis, which can lead to severe abdominal pain, fever, and potentially septic shock.
What happens if an Amoebic Liver Abscess (ALA) ruptures into the pleural space?
If the abscess ruptures into the pleural space, it can cause pleuritis, chest pain, difficulty breathing, and potentially a pleural effusion (fluid accumulation in the lungs).
What happens if an Amoebic Liver Abscess (ALA) ruptures into the pericardium?
If the abscess ruptures into the pericardium, it may cause pericarditis, leading to chest pain, difficulty breathing, and potentially cardiac tamponade (pressure on the heart due to fluid accumulation).
What is the differential diagnosis for a liver abscess?
The differential diagnosis for a liver abscess includes:
Pyogenic bacterial abscess
Echinococcus granulosus (Hydatid disease)
Hepatoma (liver tumor)
What imaging technique is most commonly used to establish the diagnosis of Amoebic Liver Abscess (ALA)?
Ultrasonography (U/S) of the abdomen and liver is typically used to establish the diagnosis of Amoebic Liver Abscess (ALA).
Can ultrasound or CT scan reliably distinguish between Amoebic Liver Abscess (ALA) and a pyogenic bacterial abscess?
No, neither ultrasound nor CT scan can reliably distinguish between ALA and a pyogenic bacterial abscess. However, ALA is commonly solitary and often found in the right liver lobe.
What is the typical size range of an Amoebic Liver Abscess (ALA)?
An Amoebic Liver Abscess (ALA) can vary in size from 2-8 cm in diameter.
What radiologic feature can be seen on both Chest X-Ray and ultrasound in a patient with Amoebic Liver Abscess (ALA)?
A raised right hemidiaphragm can be seen on both Chest X-Ray and ultrasound in patients with Amoebic Liver Abscess (ALA).
What is the significance of the white cell count (WCC) in the diagnosis of Amoebic Liver Abscess (ALA)?
A very high white cell count (WCC), often higher than 38,000/mm³, is a common finding in ALA. Historically, it was said that if the WCC is higher than the fever, the diagnosis must be ALA.
What other blood work abnormalities are commonly seen in Amoebic Liver Abscess (ALA)?
Other blood work findings in ALA may include:
- Anaemia in more than half of cases.
- Hyperbilirubinemia in one-third of cases.
- Elevated liver transaminases (AST/ALT) in up to two-thirds of patients.
- Hypoalbuminemia in up to two-thirds of ALA patients, which is more common compared to pyogenic abscesses.
How useful is stool microscopy in diagnosing Amoebic Liver Abscess (ALA)?
Stool microscopy is not very useful in diagnosing ALA, as it is difficult to find cysts or trophozoites in stool samples, with sensitivity ranging from 10-40%.
What is the sensitivity of serum antigen detection in diagnosing Amoebic Liver Abscess (ALA)?
Serum antigen detection has a sensitivity of over 95%, making it a highly reliable diagnostic tool for Amoebic Liver Abscess (ALA).
What is the sensitivity of serologic testing (Indirect Hemagglutination - IHA) for Amoebic Liver Abscess (ALA)?
Serologic testing with Indirect Hemagglutination (IHA) has a sensitivity of 70-80% in acute disease and greater than 90% in the convalescent state. In children, IHA sensitivity can be as high as 100%.
How long does it typically take for serologic testing (IHA) to become positive in Amoebic Liver Abscess (ALA)?
Serologic testing (IHA) may take longer to become positive, so it might not provide immediate results.
What is the first-line treatment for Amoebic Liver Abscess (ALA)?
The first-line treatment for Amoebic Liver Abscess (ALA) is antibiotic therapy, which includes the treatment of both ALA and intestinal amoebiasis.
What antibiotic is commonly used for treating Amoebic Liver Abscess (ALA), and how is it administered?
Metronidazole is the first-choice treatment for ALA. It can be given orally or intravenously (in cases of severe sepsis) for 7-10 days.
What is an alternative to Metronidazole for treating Amoebic Liver Abscess (ALA)?
Tinidazole is an alternative to Metronidazole for the treatment of Amoebic Liver Abscess (ALA).
What should be done if a patient with Amoebic Liver Abscess (ALA) does not respond to antibiotic therapy?
If 15% of ALA patients show no response to antibiotic therapy, therapeutic aspiration of the abscess is required. This can be performed under ultrasound guidance, and a “pig-tail” catheter may be left to drain any residual pus.
What is the next step in treating intestinal disease after treating Amoebic Liver Abscess (ALA)?
The next step in treating intestinal disease after ALA treatment is using either Diloxanide or Paromomycin. Each drug is given for 20 days.
What is the percentage of infected cases that develop extra-intestinal disease due to Entamoeba histolytica?
Extra-intestinal disease occurs in only 1% of cases infected with Entamoeba histolytica.
What are the most common and consistent symptoms of Amoebic Liver Abscess (ALA)?
The most common and consistent symptoms of ALA are:
- High fever
- Right upper quadrant pain
How is the presence of a liver abscess confirmed in suspected cases of Amoebic Liver Abscess (ALA)?
Ultrasonography (U/S) is used to confirm the presence of an intrahepatic abscess. However, it is not specific for an amoebic abscess.
How sensitive is serology (Indirect Hemagglutination - IHA) in diagnosing Entamoeba histolytica infection in children?
Serology (Indirect Hemagglutination - IHA) is nearly 100% sensitive for Entamoeba histolytica in children.
What combination of diagnostic tests should clinch the diagnosis of Amoebic Liver Abscess (ALA)?
The diagnosis of ALA can be clinched by combining serology (IHA) and ultrasonography (U/S).
What is the treatment approach for Amoebic Liver Abscess (ALA)?
The treatment of ALA is initially medical. Aspiration of the abscess is only necessary if medical treatment fails.
What was the traditional approach to diagnosing and treating Amoebic Liver Abscess (ALA) in the past?
In the past, a travel history to an endemic area, along with severe point tenderness over the liver, high fever, and a white cell count higher than the fever, was enough to make a diagnosis. The physician would then aspirate “anchovy paste pus” from the liver using a large-bore needle.
