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279: First trimester 3D power doppler of the intervillous space in patients with decreased PAPP-A levels and increased uterine artery pulsatility index

      Objective

      Decreased PAPP-A levels and increased uterine artery pulsatility index (UAPI) in the first trimester have been correlated with preeclampsia (PEC) risk and have been hypothesized to be markers of abnormal placentation. Using 3D power Doppler (3DPD) as an estimate of intervillous blood vessel density and corpuscle volume, we sought to compare 3DPD intervillous parameters in women with 1)low vs. normal maternal serum PAPP-A levels and 2)elevated vs. normal UAPI.

      Study Design

      We conducted a prospective observational study of singleton pregnancies presenting for first trimester screening. 3DPD spherical volumes were analyzed using the VOCAL™ program to determine the Vascularization Index (VI), Flow Index (FI) and Vascularization Flow Index (VFI). UAPI and PAPP-A levels were measured. The 10th percentile of PAPP-A was determined and considered low. The 90th percentile of UAPI was determined and considered elevated. 3DPD indices were then compared between groups using the student′s t-test. P<0.05 was considered statistically significant.

      Results

      275 patients enrolled. The 10th percentile for PAPP-A was 0.6 MoM while the 90th percentile for UAPI was 2.8. 28/275 patients had low PAPP-A levels. Decreased VFI was identified in these patients (9.7±4.3 vs.12.7±8.0). Although these patients also had lower VI and FI (VI 19.3±8.4 vs.23.3±12.5, FI 50.0±6.5 vs.52.1±8.7), the differences were not statistically significant. UAPI measurements were adequately performed in 265/275 patients. 26/265 patients had UAPI>2.8. All 3DPD parameters were similar in those with elevated vs. normal UAPI.

      Conclusion

      Patients with low first trimester PAPP-A levels had reduced VFI supporting the hypothesis that low PAPP-A is associated with abnormal placentation. 3DPD parameters were not significantly different in women with increased first trimester UAPI suggesting that the uterine artery changes of PEC may not be directly related to abnormal placentation.