Study of ultrasonographic, color Doppler and Biochemical parameters In patients with first trimester- Threatened abortion.Transvaginal ultrasound shows that there were significant early gestational sac growth delay and early fetal CRL growth delay in threatened abortion compared to normal early pregnancies .Color Doppler studies shows that RI & PI in both uterine & subtrophoblastic arteries increase significantly with decrease blood flow. It may explain early gestational sac growth delay and early fetal CRL growth delay in threatened abortion compared to normal early pregnancies.In threatened abortion, Transvaginal color Doppler ultrasound may add new information on RI &PI of both uterine & subtrophoblastic arteries with follow up measurements of MSD, CRL, FHR, and HCG level to allow further evaluation of the threatened abortion outcome.