Yes I have had one last year.
It is not as bad as it sounds .
It takes about 5-10 minutes, the Dr injects dye into your uterus which flows into your fallopian tubes. This enables the DR to see if there is any blockages or kinks in your tubes.
You have to position your self on the couch in the xray room, like you were preparing to have a smear taken (the DR and assistants are lovely and make you feel relaxed and comfortable). They will always carry out a pregnancy test before they carry out the HSG just to make sure you are not pregnant (you provide a urine sample when you arrive).
A speculum is inserted into your vagina (like you are having a smear) and the DR inserted the littles injection tube (you can't feel it)and using an xray machine he makes sure it is in the right place, then he injects dye which goes into the tube, flows into your vagina and into your fallopian tube. He then takes a series of xrays, while this is happeninf
When the dye is going in......it does hurt, like bad period pain.....but only lasts for split seconds as he injects the dye in. I advise you to take some pain killers such as Brufen about 1 hour before the test, so that you have some pain relief on board.
Anr finally just to say, it is over very quickly, a bit of period pain for a few seconds is well worth finding out if things are ok.
Oh! most important... they do say that when you have this test done it kind of flushes out your tubes and clears them out! (I got pregnant 2 months after my test!!!)
GOOD LUCK!