Summary
Prenatal identification of placenta accreta is essential to manage optimal delivery circumstances for these women (Kayem et al., 2013). Authors reported that women with a pre-delivery diagnosis of placenta accreta for whom a cesarean hysterectomy with no attempted removal of the placenta, required fewer units of packed red blood cells and tended to have a lower estimated blood loss than those with no predelivery diagnosis (Tikkanen et al., 2011).
The present study was conducted to evaluate the different ultrasonic markers used to diagnose placenta accreta. The study enrolled 103 pregnant women more than 28 weeks gestation attended Benha University Hospitals with placenta previa. All patients included in the study underwent operative abdominal delivery at our hospital.
Routine ultrasound scan was done at weekly interval for evaluation of placental invasion including loss of retroplacental clear zone, myometrial thickness, intraplacental lacunae, bridging vessels, uterine-bladder interface, exophytic mass into bladder space and the placental accreta index. The results of different ultrasound criteria and the placental accreta index in the last scan before delivery were correlated with the clinical and/or histopathological confirmed placenta accreta (45 cases) or non-accreta (58 cases).
Our data highlighted the significant direct relationship between incidence of placenta accreta with increasing maternal age, gravidity, parity and increasing number of prior cesarean section.
The grayscale and color Doppler ultrasound have good performance in the diagnosis of PAD. Evaluation should be based not only on sensitivity and specificity but also PPV, NPV and RR is mandatory to planning appropriate counseling and management.
In our study, the highest sensitivities of ultrasound markers were lacunae and loss of retroplacental clear zone. The highest specificities and PPVs were bridging vessels and sagittal smallest retroplacental myometrial thickness < 1 mm. The highest NPVs were lacunae and Loss of retroplacental clear zone.
The highest relative risk of ultrasound marker with placenta accreta was lacunae followed by loss of retroplacental clear zone and bridging vessels.
Placenta accreta index score derived from the ultrasound parameters of smallest myometrial thickness, lacunar spaces, and presence of bridging vessels, in addition to the number of prior cesarean deliveries and placental location, was highly predictive of placental invasion among pregnancies at increased risk.
In our study, receiver operator characteristic curve for PAI with AUC of about 89% which indicate accuracy of the PAI score. We concluded that PAI >5.4 could be the best diagnostic predictor for MAP. It may be used for counseling and preoperative planning, also play a role in identifying women who may benefit from referral to a tertiary center that has sufficient blood bank capacity and multidisciplinary services.
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