In this article, we will discuss the Diagnosis of Amoebic Liver Abscess. So, let’s get started.
The diagnosis of amoebic liver abscess is made on history of fever, right hypochondrial pain with tender hepatomegaly. It is confirmed on ultrasound and other tests.
Stool examination for trophozoites is usually negative. At least 3 stool specimens should be evaluated after concentration and staining.
WBC count may show leukocytosis (>10000 cells/mm3). There may be anaemia.
Ultrasonography of liver: It is useful non-invasive test to identify an abscess as a hypoechoic cyst or cavity with irregular shaggy walls. The abscess is more common in right than left lobe on its posterosuperior surface. Multiple abscesses are likely to be pyogenic. Satellite lesions (microabscess) may be present around the main lesion. However, multiple lesions spread all over the liver in amoebic liver abscess should make one to suspect an immunocompromised state which should be investigated. The USG findings change with the duration of the illness from a solid lesion, abscess-in-evolution to abscess formation. It is made clear that size usually increases with treatment and does not warrant aspiration unless associated with no response to treatment or impending rupture.
CT scan/MRI: This investigation do not have any advantage over USG which is gold standard for diagnosis of an amoebic liver abscess.
Serological tests: Indirect hemagglutination (IHA) and ELISA tests for amoebiasis have been the most extensively employed confirmatory tests and are almost always positive accept very early in infection. Low titres are not diagnostic of recent infection. Titres >1:1024 are diagnostic of amoebic liver abscess. A negative IHA for amoebic liver abscess should be repeated after one week and if found again negative, it rules out amoebic abscess and warrants further investigations to look for other etiologies like pyogenic abscess, primary or secondary hepatocellular carcinoma or an infected cyst. A commercially available amoebic antigen test (Tech Lab II) claimed to have sensitivity of >90% in amoebic colitis, can be used in serum with sensitivity of 40%. It should be done before start of treatment.
When diagnosis is uncertain and there is high possibility of the abscess to be pyogenic, a diagnostic aspiration may be done. Demonstration of trophozoites in the aspirated fluid is not easy and their absence does not help in the differentiation of amoebic from pyogenic abscess. Aspiration for Gram staining and culture will help when diagnosis is in doubt.
Other routine tests such as liver function tests are normal. However with large liver abscess, the alkaline phosphatase, bilirubin and amino-transferases may be elevated slightly.
Fluoroscopy may show limitation of movement of right dome of the diaphragm.
X-ray chest (PA views): It is done to detect the complications such as pleural or pericardial effusion. Right dome of the diaphragm may be raised in amoebic liver abscess.