Ascariasis Workup

Updated: Jul 30, 2018
  • Author: David R Haburchak, MD, FACP; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Workup

Laboratory Studies

Stool examination for ova and parasites almost always discloses large, brown 60 µm X 50 µm trilayered eggs in persons with ascariasis. However, stool examination may be negative for ova for up to 40 days after infection because of the time needed for migration and maturation of the worm. The outer surfaces of fertilized eggs have an uneven mucopolysaccharide coat.

Ascaris larvae may be observed in microscopic wet preparations of sputum during the pulmonary migration phase.

CBC counts show eosinophilia during the tissue migration phase of the infection.

Serological tests are not clinically useful for ascariasis.

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Imaging Studies

Radiologists practicing in Europe and North America should be familiar with unexpected but specific abnormalities associated with parasitic disease, especially in this age of increasing migration and tourism. [25]

Chest radiographs may show fleeting opacities during pulmonary migration.

Abdominal radiographs may show a whirlpool pattern of intraluminal worms. Narrow-based air fluid levels without distended loops of bowel on upright plain films suggest partial obstruction. Wide-based air fluid levels with distended loops suggest complete obstruction.

Worms have been increasingly identified in the biliary duct or gallbladder with ultrasonography and CT scanning. [26] Liver granulomata due to A suum infection have been described as ill-defined, 3- to 35-mm, nodular- or wedge-shaped lesions in the periportal or subcapsular regions.

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Other Tests

Endoscopic retrograde cholangiopancreatography (ERCP) has become a commonly used procedure for both diagnosis of ascariasis and removal of worms from the biliary tract. The ease of diagnosis and therapy in the same setting makes ERCP particularly valuable when used with real-time ultrasonography. The combined procedures yield a sensitivity of nearly 100%. [22]

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