Hi, in first scan the foetus visble , wth heart beat 130 bpm and crl 5.2mm and age 6 wwweeks 1 day with vagina bleeding, aftertwo days red blood bleeded went fr scan again, shown feat heart absent, peri sac founded with 9 mm thckness and told missed abortion, and starting while testing urine the line was very thin and shwn preganancy with weakly positive...what may be the reason ?