Okay, I am so glad you asked this question because I went into an HSG COMPLETELY unprepared and my doctor's office told me absolutely NOTHING about what to expect. I wasn't even told to have someone drive me to the hospital - I just thought it was similar to an ultrasound. Now, don't get scared because I know a couple of other people who had this done and it didnt' bother them very much, so it's different for everyone. But I wasn't even warned beforehand that it could potentially be painful.
So to be honest with you, this was one of the most painful things I have ever experienced in my whole life. I have had two children and it was right up there, if not worse, then childbirth. The doctor was really casual about it and injected the dye in there, and seriously the wind was knocked right out of me because the pain was so bad. I was like "Is this supposed to hurt this bad?" He was like "Yes, this can be uncomfortable for a minute." Once he was done and the dye was out, I was still in so much pain that I didn't think he was done yet. So it was all very quick and the nurse didn't even check to make sure I was ready to walk or anything and she walked me back to the little dressing area with stalls to change and left me alone. So I was still reeling from pain and feeling awful and I sat down for a minute in the stall and I started to feel woozy and I seriously wondered if I was dying or something and even looked between my legs to make sure I wasn't hemmorraging or something crazy - it was scary. So anyway, then I full on fainted on the floor of the stall. When I woke up, I was weakly calling "hello? hello?" but no one was around and finally I dragged myself to the door and stuck my head out and someone saw me and I probably looked like death so they came over and put me on a stretcher and hooked me up to monitor my vital signs, etc., and kept me that way for at least an hour. The nurse was really surprised that no one had told me that someone should drive me to the hospital and I had to call my husband and wait for him to come get me. It was so traumatic! I am so sorry to tell you all of this and I don't want to scare you, because obviously my experience is like the worst case scenario and like I said, this procedure was only mildly uncomfortable for a couple of girls I know. I just was quite upset about having no warning about how painful it can be for some women. So, hopefully it will not be too bad for you. And also, best of luck with the whole infertility thing. It is definitely NOT FUN to say the least!