ecups, when they do the HSG test, they will pump a type of dye into your tubes then they do xray. if your tubes are blocked, the dye cannot pass thru at all. my case was slightly blocked hence i got a cramp when the dye was forced to get thru. at least it unblocked for me.
for me, it is not because of the tubes but was because of the blood cyst in my brain. after removal of that blood cyst, 2 mths later i got pregnant.
perhaps my body wasnt ready at that time when i got pregnant. the egg quality is no good and yet have to split into 2.