How often do you get sonohysterogram done?

I recently had a SHG done before starting another

IVF

cycle. During the last one, we found a polyp. I’m not sure when the polyp developed because I didn’t know what symptoms, if any, I was supposed to watch for. Since I’ve had SHG done prior to only fresh cycles, I’ve always associated it with fresh cycles. Does this test need to be done before FET cycles, too? (I should also ask my doc!)

Also, how would a woman TTC know if she has polyps if a SHG isn’t a part of regular checkup? Polyps are not seen with regular ultrasound or pap. And I’ve read that they can come back after surgery. 🤔