Aim of the work: This case control study was done to to evaluate whether measurement of cell-free fetal DNA in the maternal plasma can be predictive of abnormal placental invasion in cases of placenta previa.
Methods: It was conducted on 50 healthy pregnant women. After being provided with an informed consent, they were allocated in two groups. Group one: study group previously diagnosed as placenta previa anterior only or with ultrasound finding suggestive of placental adhesion or invasion (n=25) while group two :matched control with normally situated placenta without ultrasound finding suggestive of placental adhesion (n=25). This study exclusively limited to singleton pregnant women carrying male fetuses, gestational age range from 28-34 weeks, para 1 - para 5, maternal age range from 20-40 years old and body mass index range from 18-25 kg/m². This study excluded women with multifetal pregnancy, hypertension, preterm labor and intrauterine growth restriction and patients were taking a tocolytic agent or those with uterine bleeding at or immediately after blood sampling. The blood samples were processed within 24 h and DNA was extracted from plasma using QIAamp Blood Mini Kit (Qiagen). The TaqMan real time PCR analysis was performed using a PE Applied Biosystems 7500HT Fast Real-Time PCR Sequence, Detector was employed to design SRY primers using the SRY gene sequence.
Results: The main finding of this study was that, there were no statistically significant differences regarding the level of free fetal DNA (F-FDNA) between placenta accreta (PA) group and control group. In this study highly significant statistical differences were found regarding the incidence of preterm delivery with placenta accreta group and highly significant statistical differences regarding the increased maternal age in same group. Significant statistical found positive correlation between level of F-FDNA in maternal plasma and gestional age, F-FDNA increases as gestational age advances. There was no significant statistical correlation between level of F-FDNA in maternal plasma and maternal age while there was significant statistical negative correlation between level of F-FDNA in maternal plasma and body mass index (BMI), F-FDNA decrease in maternal obesity. Comparing between the two groups there were high significant statistical differences regarding the increased number of Cesarean deliveries in placenta accreta group more than control group. Seven women in placenta accreta group were treated with cesarean hysterectomy due to sever intrapartum hemorrage, histopatholgical examination of removed uteri and adherent placenta revealed 1 placenta accreta (14.3%), 3 increta (42.9%) and 3 percreta (42.9%).
Conclusion: No significant association between cell free fetal DNA (cffDNA) and placenta accreta (PA). Obesity during pregnancy is associated with lower ff DNA, gestational age is an additional factor that can affect the ff, levels of fetal DNA increase throughout pregnancy.