Validation of placental vascular sonobiopsy for obtaining representative placental vascular indices by three-dimensional power Doppler ultrasonography.

OBJECTIVE

Placental vascular sonobiopsy has been proposed for obtaining a representative sample of the placental vascular tree when evaluation of the whole placenta is not feasible. We tested the hypothesis that placental vascular indices from sonobiopsy correlate well with those from the entire placenta.

METHODS

Three-dimensional power Doppler ultrasound examinations were performed in 120 singleton pregnancies at 11-14 weeks' gestation. The VOCAL program was used to calculate placental vascularization index (VI), flow index (FI) and vascularization flow index (VFI) from stored images of each placenta by whole placenta evaluation and placenta vascular sonobiopsy. The mean of each index from four spherical sonobiopsies were compared to those from evaluation of the entire placenta for their degree of correlation and agreement.

RESULTS

The mean VI and VFI from the two techniques were similar (13.9 [95% CI 12.3-15.8] versus 14.3 [95% CI 12.1-17.0], p = 0.62 and 6.1 [95% CI 5.2-7.1] versus 6.1 [95% CI 5.0-7.4], p = 0.93, respectively) and significantly correlated (Pearson's r = 0.70 [95% CI 0.60-0.78, p < 0.001] and r = 0.69 [95% CI 0.58-0.77, p < 0.001], respectively). The mean FI from the two techniques were significantly different (44.5 [95% CI 42.9-46.1] versus 41.3 [95% CI 39.6-43.0], p = 0.001), but correlated (r = 0.59 [95% CI 0.46-0.70, p < 0.001]).

CONCLUSION

Our findings suggest that placenta vascular indices from sonobiopsy have a good correlation with those from evaluation of the entire placenta. Sonobiopsy may be a valid alternative for evaluation of the placental vascular tree when visualization of the entire placenta is not feasible. Measurements of VI and VFI appear to be more reliable than FI in sonobiopsy specimen.