I've had lots of background checks for safety-sensitive positions, and none of them contained medical information (and I'd been hospitalized once before for suicidal thoughts). I've been asked
personally about medical history upon a job offer, but my medical records are protected by HIPAA laws.
You should ask for a copy of the report when an employer asks your permission to check. It's your info after all, and there could be errors. I don't think they have to give you a copy, but it doesn't hurt to ask.
Most employers want to make sure you're not a criminal. Attempted suicide isn't a crime in the US under federal law (Maryland is...different).
Unless you're applying for a job requiring high level security clearances and extensive psychological testing, you should be fine