Uterine Artery Doppler Velocimetry in Placenta Previa and Placenta Accreta

Abstract
Background: Placenta previa and placenta accreta are common obstetrical problem. Placenta previa is partially or totally implanted placenta in the lower uterine segment, this abnormality in the site occurs with different degrees, placenta previa lateralis, marginalis and centralis either incomplete or complete. Abnormal placental adhesion means that the placenta invades the uterine myometrium with different degree. This morbid adhesion is called “Placenta Accreta”, with different grades according to the degree of the trophoblastic invasion through the myometrium and bladder serosa as placenta accreta vera, placenta increta and placenta percreta. Incidence of placenta accreta is increased over the past years mainly due to increasing rates of cesarean delivery. Placenta accreta may lead to massive obstetric hemorrhage with attempt to remove the placenta leading to several complications up to death. Diagnosis of placenta accreta can be done by different modalities such as Ultrasound Grey scale, Color Doppler, Magnetic Resonance Imaging (MRI). Ultrasonography is usually employed as the primary modality for antenatal diagnosis of invasive placentation. Over recent years, Color Doppler Sonography (CDS) have been started to be used to predict placental abnormalities. CDS, a noninvasive and simple tool, is useful indistinguishing normal and abnormal placentation.
Aim of Study: The aim of this work was to study uterine artery doppler velocimeteric changes in patients with placenta previa and placenta accrete.
Patients and Methods: 30 pregnant females were included in this comparative prospective clinical study subdivided into two group; Group (A) Includes 15 patients with anterior placenta previa, and Group (B) Include 15 patients with anterior placenta previa accrete. Both groups were diagnosed by trans-abdominal Ultrasonography either from outpatient clinics or inpatient department of Tanta University Hospital seeking for antenatal care from Octorber 2017 to August 2018. All patients underwent uterine artery Doppler velocimetry to measure the mean Resistive Index (RI) and Pulsatility Index (PI) in the third trimester and compared between both groups.
Results: the mean uterine artery velocemtric changes including mean Resistive Indices (RI) and mean Pusitility Indices (PI) were significantly lower in the placenta accreta group compared to placenta previa group (with mean for RI 0.41 versus 0.45; p=0.001) and (with mean for PI 0.50 versus 0.56; p=0.001), the uterine artery Doppler values in combina-tion with maternal characteristics, such as previous history of cesarean deliveries, will improve screening accuracy of placenta accrete (p=0.022). Conclustion: This study suggests that the mean PI and RI measured by uterine artery Doppler velocimetry is reduced in patients with placenta accreta compared to those without accreta. Accuracy of diagnosis can be potentially improved in invasive placentation if uterine artery Doppler values and the history of cesarean delivery are combined.