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227: Can 3D power doppler analysis of a potentially morbidly adherent placenta improve the prenatal diagnosis of this condition?

      Objective

      To compare the ability of 2D ultrasound vs. 3D power Doppler to objectively predict the morbidly adherent placenta (MAP).

      Study Design

      Prospective cohort study of women with known placenta previa. Ultrasound exam was performed between 28-32 weeks of gestation using GE Voluson E8 with both 2D color and 3D power Doppler flow studies (pre-established settings). Clinical decisions were made based on 2D diagnosis of MAP, which included: abnormal lacunae, loss of retro-placental sonolucency, or thinning of the uterine serosa-bladder line. 3D power Doppler volumes (120° acquisition) were assessed for vascular (VI), flow (FI), and vascular flow indices (VFI=VI x FI) by manual tracing of the entire viewed placenta; data was blinded to clinician. MAP was confirmed by histology after hysterectomy. Severe MAP was defined as the presence of all the following 3 criteria: increta/percreta on histology, calculated blood loss >2000 ml, and >2 units of PRBC transfused. Student t-test, logistic regression, receiver-operating characteristic (ROC) curves, and intra and inter-rator agreements using Kappa statistics were used.

      Results

      Forty-one women were analyzed: 20 had MAP, of which 10 (50%) were severe MAP. Prior C-section was 94 % in MAP vs 33 % in No MAP (p=0.01). Gestational age at enrollment did not differ in MAP vs No MAP (30.6±11.3 weeks; 30.8±9.2 weeks; p=0.21). 2D parameters diagnosed MAP with a sensitivity (SN) of 80.1% (95%CI 72.6-91.7) and a specificity (SP) of 90% (95%CI 81.5-97.4), For severe MAP, 2D US had a SN 30% (95%CI 9-30) and SP 100% (95%CI 94-100). For the 3D power Doppler US, mean values of VI and VFI were significantly higher in MAP [Table]. Area under the ROC curve for VI and VFI to predict MAP was 0.99, and 0.98, respectively. VI ≥21 predicted MAP with SN and SP of 95 and 91% respectively. For severe MAP, VI ≥31 had SN 100% (95% CI 72-100) and SP 90% (95% CI 81-90). The intra and inter-rator agreements for ± 1 unit on 3D volume tracing and indices were 94% and 93%, respectively (p<0.001).