My OB gave me this exact pessary, except he told me to insert it knob-first. It seemed to be working fine, until I got period. I had pain like I've never felt before, intense cramping after I took it out and it seemed to stop my flow (for example, I put it in the first day of my period before it had started. When I took it out, there was pink discharge and I knew my period was starting but it never flowed out after I removed the pessary - I just had intense cramping most of the day and my period didn't start flowing until the following day). So sorry for the long-winded question - but I'm trying to understand what was happening by inserting it knob-first versus knob-facing-out. Hopefully that makes sense.