fluid in uterus for iui??

[sprite30]

I went in this morning to be checked and I thought they were going to cancel my iui cycle. I had 4 mm of fluid in my uterus cd 10 and I am brown spotting. They ultimately decided to proceed in the hopes that by the time we do the iui the fluid will have come out. She said I can get pregnant with fluid. I'm just wondering now if we have very slim chances or does this happen all the time??