Enterobius vermicularis ova in a pap smear: typical and uncommon morphology

Enterobius vermicularis (oxyurid), commonly named pinworm, is the most frequent nematode to infect humans and causes the most common helminth infection in developed countries. Its life cycle and transmission are well known.1 Adult worms are found in the cecum, appendix and colon. The fertilized female migrates to the perianal area, where eggs are deposited but occasionally introduces itself into adjacent orifices, most commonly the female genitourinary tract. The presence of pinworm eggs in cervicovaginal smears, with a description of their typical morphologic characteristics, is well documented.2-4 Nevertheless, demonstrating peculiar forms or ones distinct from the established ones is not frequent.