Pediatric Ascariasis Workup

Updated: Jan 05, 2015
  • Author: William H Shoff, MD, DTM&H; Chief Editor: Russell W Steele, MD  more...
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Workup

Laboratory Studies

Adult worms may be coughed out, vomited, or passed via the rectum and studied.

A microscopic examination finding of eggs in the feces confirms the diagnosis. This is performed using a direct method (stool mixed with saline) or after concentrating the stool. The Kato-Katz method is the preferred method. Fertilized eggs are easier to identify than unfertilized eggs and decorticate eggs, which are infrequently produced and lack the outer covering. Male-only ascaris infections produce no eggs. Microscopic examination of gastric contents may reveal larvae and eggs. Microscopic examination of sputum may reveal larvae.

Eosinophilia (5-12%) may occur, particularly during the lung migration phase, and can be as high as 50% in ascaris pneumonia.

Serology is used for epidemiological purposes and is not useful for diagnostic purposes.

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Imaging Studies

Chest radiography

According to Löeffler, "The x-ray shadows are variable, unilateral or bilateral, fleecy or dense and small and round or big and irregular; they may be very extensive. They usually appear within three days and disappear in about 10-12 days." Follow-up radiography several months after the acute illness reveals no residual abnormalities.

Abdominal ultrasonography

This is the study of choice for imaging Ascaris worms in the biliary tree. Worms may be single, multiple, in bundles, and moving during the examination.

Abdominal CT scanning  [18, 39]

An alternative study to abdominal ultrasonography. A thin line of dye is occasionally seen within the corpus of a worm that has swallowed dye. Within the biliary tree, the worm is more easily visualized on an unenhanced scan. Double-contrast abdominal CT scanning is an excellent study for the evaluation of a patient who presents with acute abdominal symptoms suggestive of intestinal obstruction or another surgical emergency.

Magnetic resonance cholangiopancreatography (MRCP)  [19]

This is an alternative to abdominal ultrasonography when it is not feasible, as is the case in some pregnant women. It is good for a general evaluation of the pancreatobiliary organs. It is an alternative to abdominal CT scanning when radiation exposure is to be avoided.

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