RESUMEN
OBJECT OF STUDY: Retained products of conception (RPOC) displays variable vascularity, ranging from avascular to markedly vascular on color Doppler sonography. We hypothesize that variability in sonographic vascularity may be due to histopathologic variation in the placental tissue. MATERIALS, METHODS, AND PROCEDURES: After institutional review board approval, sonographic images and pathologic specimens were retrospectively reviewed in 26 patients with pathologically proven RPOC. Ultrasound (US) images were scored 0-3 for the degree of vascularity by two radiologists blinded to the diagnosis. Corresponding pathologic specimens were evaluated for vascularization of chorionic villi, degree of inflammation, morphology of maternal arteries, chorionic villous preservation, and percentage of clot, membranes, chorionic villi, and decidua/myometrium. Statistical analysis, including multiple linear regression, was performed. RESULTS: RPOC with histologically avascular chorionic villi or those with markedly reduced vascularization had significantly lower US vascularity scores (p = 0.030) than those with chorionic villi showing normal or decreased vascularization. Sonographically avascular RPOC had a significantly lower percentage villi (p = 0.028) and higher percentage of decidua (p = 0.004) than specimens where US showed any Doppler vascularity. Histologic vascularity of villi (p = 0.049) and non-observation of maternal arteries (p = 0.001) were significant predictors of US vascularity scores in multivariate linear regression analysis, while inflammation of villi (p = 0.053) was a marginally significant predictor. SIGNIFICANCE OF THE CONCLUSIONS: Histologic vascularity of villi appears to contribute to the observed variation in sonographic vascularity. This finding may underlie known differences in clinical outcomes between sonographic vascularity groups.