This study finds that the use of transvaginal Doppler for assessment of uteroplacental circulation in cases of threatened abortion is not useful as a predicator of pregnancy outcome. Also the use of measurement of β-HCG is not useful as predictor of pregnancy outcome as there is great variation of β-HCG level in normal pregnancies. The blood supply to the uterus comes from the uterine arteries the main branch of each artery enters the uterus just above the cervix and ascends along the lateral part of its wall these peripheral branches give rise to the arcuate arteries that derive their name from their arching pattern in the uterus.