HI, I understand your concern. After IUI the injected semen fertilizes the ovum.. so mostly IUI is done around ovulation. The ovum is viable till 36 hours & sprm remains active for 3 days of ejaculation. After fertilization the fertilized ovum migrates to uterine cavity & gets implanted by 8 th day of fertilization. In your case the bleeding can be implantation bleeding.. Which is evident in many patients. So please don t worry, be +ve. you do have all the chances to conceive successfully this time.( IUI being simplest way to aid conception & also all the factors as detailed above, needs to be repeated a couple of times ).. Crinone is a hormone essential for maintenance of pregnancy.. you should continue to use it/ avoid physical or psychological stress & wait patiently for +ve response. Thanks.