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 examination, 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 institutionalisation

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

weak

Oral habits like nail biting or thumb sucking

Auto-inoculation 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.[11][17][18][19][20]​

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