Ultrasound for infertility?

Lauren
Hi ladies!
I'm on month 4 of TTC and my periods have been super irregular (50-60 days per cycle). My OBGYN wants me to come in for an ultrasound next month to make sure everything's ok in there. Anyone else had an ultrasound for infertility? Is it pretty common as a first step? I'm curious about what they can find out from it.
Thanks!
Lauren