Screening for ADHD is the process of figuring out if it's worth while to get assessed for ADHD. There are lots of screening tests on the internet but the most recognized one for adults is the ASRS.
A positive screen does not justify a diagnosis or treatment, but neither does a negative screen rule it out. The highly organized person will under report symptoms while the anxious might over report.
Caddra.ca is a good resource for other screening tests, for assessing dysfunction or for screening children.