History and exam

Key diagnostic factors

common

perianal pruritus

Perianal itching is the most common presentation of pinworm infection.

perianal erythema

May be excoriated.

uncommon

presence of worms

Occasionally, adult pinworms may be seen on exam, especially if performed at night, when females deposit their eggs on the perianal surface.

Other diagnostic factors

common

restlessness

Perianal itching is worse at night and may be associated with restlessness.

insomnia

Perianal itching is worse at night and may be associated with insomnia.

uncommon

vulvar pruritus

 Itching may extend from the anus to the vulva.[1]​

Risk factors

strong

school attendance or institutionalization

Pinworms are easily transmissible and most common in school-aged children. Prevalence rates are also higher in institutionalized people. Outbreaks have occurred in classrooms and in institutions.[1]

weak

Oral habits like nail biting or thumb sucking

Autoinoculation can occur via the transfer of eggs to the mouth with hands that have touched or scratched the perianal area. Children who bite their nails or suck their thumbs may therefore experience higher rates of infection.[12][17][18][19][20]​

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