Placenta Accreta spectrum is a major obstetric disease nowadays. Different methods are used for antenatal diagnosis. In our study, investigators are aiming to compare 2 common ways for diagnosis, i.e; 3D Ultrasound and 2D with color Doppler.

The word placenta accreta spectrum disorders (PASD) implies an atypical implantation of the placenta into the uterine wall and has been used to express placenta accreta, increta and percreta. Placenta accreta is a placenta where the placental villi sick on directly to the myometrium. Placenta increta is a placenta where the placental villi attack into the myometrium and placenta percreta is a placenta where the villi invade through the myometrium and into serosa. No antenatal diagnostic method gives the clinician 100% assurance of either ruling in or ruling out the existence of placenta accreta. The definitive diagnosis of placental accreta spectrum is frequently ended postpartum on hysterectomy specimens when an area of accretion shows chorionic villi which make direct contact with the myometrium and absence of deciduae. Antenatal ultrasound is the method of choice used to establish the diagnosis and direct clinical management.The combined use of power Doppler with three dimensional (3D) ultrasound provides the possibility of quantifying moving blood within a volume of interest. Three indices are calculated, namely vascularization index (VI), flow index and vascularization flow index

Inclusion Criteria:

• pregnant women with placenta previa

Exclusion Criteria:

• congenital anomalies of placenta Placental separation Uterine anomalies

All patients with placenta previa from 24 -39 weeks will be counselled to participate in the study. Patients will be enrolled in one of the 2 groups. Group 1, 3D Ultrasound with placental volume and vascular indices will be calculated. Group 2 , 2D ultrasound parameters and color Doppler study will be performed.