Methods to detect table boundary in pdf?

I am attempting to retrieve data from table(s) in pdf manuals. Unfortunately it would seems like the selectors do not seem to be consistent even after enabling assistive technology on Adobe Acrobat (the selectors don’t work, or take chunks of paragraphs that don’t go together. The tables are not bordered but the headers are underlined. Is it possible to use another method, eg. OCR to detect the table boundary?