Appearance of the uterus by ultrasound immediately after placental delivery with pathologic correlation.

The purpose of this study was to compare the ultrasound appearance of the uterus immediately after the placenta was delivered with the gross and histologic findings obtained by manual exploration and sponge curettage. One hundred thirty-one patients underwent a sonographic assessment of the uterus within 5 minutes of placental delivery. A manual exploration and sponge curettage were performed with 2 minutes of the ultrasound examination, and the specimens were assessed for gross and histologic evidence of retained products of conception. Twenty-four (18.8%) of the patients had documented evidence of retained products of conception either by gross inspection or histologic assessment. Nineteen (15%) of the patients had what appeared to be retained products on ultrasound examination. Using our sonographic description of retained products of conception, the sensitivity, specificity, positive predictive value, and negative predictive value of ultrasound in detecting retained products was 44%, 92%, 58%, and 87%, respectively. The ultrasound findings in patients with retained products of conception were: a normal endometrial cavity in 9 (37.5%), echogenic mass in 6 (25%), heterogenous mixed density mass in 5 (21%), and fluid only in 4 (16.6%). Of the 6 cases with an echogenic mass, all were associated with retained products of conception. The ultrasound appearance of retained products of conception in the immediate time period after placental delivery is highly variable.