I agree with lmcrt...sounds like you have a cyst (a leftover follicle from the previous cycle). I had a cyst a few months ago and it was 40mm! But the good news is that they usually go away by themselves. Mine was gone again by the end of the cycle. I'm not sure why having one 17 mm cyst would indicate OHSS, though. It's pretty common to get a cyst, especially when on fertility meds. But maybe like lmcrt, your ovaries were larger than normal and that's why your doctor is considering OHSS.
Best of luck with your new cycle! And keep us posted when you get the lab results...
:-)
Did you go through IVF or IUI.......If so it is common to have left over follicles that remain large. I did IVF and a month later still had follicles measuring in the 20mm range. My ovaries were three times there size. I had horrible bloating but nothing I couldn't deal with. However my RE told me I must have a high pain tolerance becuase most women would be in her office crying of pain with follicles this large. I didn't feel any pain just bloating and a little hard to breath. So I guess it depends upon the individual as to how much OHSS they can handle. Good luck