Enterobius vermicularis

Reviewer: Jaleh Mansouri, M.D. (see Authors page)

Revised: 18 March 2016, last major update August 2012

Copyright: (c) 2003-2016,, Inc.

PubMed Search: Enterobius vermicularis appendix
Cite this page: Enterobius vermicularis. website. Accessed October 21st, 2016.
Definition / General
  • Also known as pinworm
  • Formerly known as oxyuris vermicularis, oxyuriasis
  • Most common helminthic infection in children, affects all social strata in the US
Clinical Features
  • Usually more common in temperate climates
  • Usually found in appendix of children ages 7-11 years as incidental finding
  • Mass of worms may cause obstruction
  • May occasionally be associated with appendicitis (Pediatr Surg Int 2004;20:372, Southeast Asian J Trop Med Public Health 2007;38:20)
  • Eggs often deposited at night on perianal skin, causing pruritis ani, irritability, loss of sleep (DPDx - Enterobiasis)
  • Eggs can be diagnosed with the cellulose tape technique on perianal skin when child wakes up
  • Adult worms may migrate to the lower genital tract and cause a granulomatous reaction
Case Reports
Gross Description
  • Worms reside in cecum, 1.3 cm long
Micro Description
  • Cross section has narrow lateral cuticular alae
Micro Images
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Case of the Week #90: eggs

An 8 year old child, presenting with acute appendicitis
Contributed by Dr. Wafaey Fahmy Badawy Mohamed, Armed Forces Hospital, Hafr Albatin, Saudi Arabia

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Contributed by Dr. Guido Nicolò (Italy)

Enterobius in appendix

Various images

Cytology Images

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Ova and larva of Enterobius vermicularis

Differential Diagnosis
  • Vegetable matter, whipworm