HSG – Xray dye study of the tubes
I had an HSG (x-ray dye study of the tubes) performed, and they didn’t see one tube. Does that mean I don’t have a tube? Why wasn’t I told this before?
Wait just a minute before panicking. I need to help explain some things. When you had the HSG performed, if the radiologist or doctor didn’t see your one fallopian tube, that does not necessarily mean that it is absent or not working at all. If a uterus is normal, then it would be extraordinarily rare for one or both tubes to be absent. When one tube doesn’t show up on the HSG, it is usually has a simple explanation. There is a small muscle at the opening (the ostia) that leads from the uterus into the tube. This is a round sphincter muscle, just like the anal sphincter. When dye is injected into the uterus, these muscles often spasm, closing down tightly. Once they do this, they do not relax easily. So if the dye goes out one tube, and the other tubal openins is having a spasm, the dye just follows the path of least resistance and continues to go out the open tube. With this happening, pressure cannot be built up inside of the uterus to overcome the spasm of the other tube opening.
If the fallopian tube filled with dye and was blocked at the end, then that is a different story. But of the tubes that don’t even fill up, well over 90% of them are normal. The tubal spasm is a side effect of the HSG and is sometimes more commonly found if the HSG is not carefully performed. There can be scar tissue at the opening causing it to be scarred shut, but that is not commonly seen. Tubal scar tissue usually affects the end of the tube and only rarely at the point where the tube joins the uterus. Occasionally there can be a polyp, or endometrial overgrowth, that is right in front of this opening and could serve to block the ostia. We used to take all of these patients to laparoscopy to investigate this, and after doing this time and time again, what we realized was that nearly all of them were normal at the time of surgery. Going to surgery is still a reasonable option for some patients, though, depending on the situation. If one tube appears to be working normally, then more conservative therapy could be used.