Transabdominal sonography before uterine exploration as a predictor of retained placental fragments

To evaluate the diagnostic accuracy of sonography in postpartum patients thought to have retained placental fragments.

The study group consisted of 39 postpartum women in whom inspection of the placenta brought up suspicion of retained placental fragments. All these women underwent manual exploration of the uterine cavity. Before the procedure, all patients had two-dimensional sonographic imaging, after which they were divided into 2 groups. The first group comprised women who were judged to have had an empty uterus or nothing but intrauterine fluid collection. The second group consisted of those in whom sonography showed echoes of what might appear as residual trophoblastic tissue, that is, echogenic, hypoechoic, or mixed echo intracavitary patterns. The sonographic patterns were then correlated with the presence or absence of retained placental fragments as found on uterine manual exploration and pathologic examination.

In 18 patients, no suspected contents were observed on sonography. In 17 of these patients, the uterus was empty on manual uterine exploration. One of these patients had residual trophoblastic tissue, which was of minimal quantity and clinically unimportant. In 21 patients, sonography suggested retained placental tissue. In 15 of these patients, pathologic examination confirmed residual trophoblastic tissue, and in the remaining 6, the uterus contained blood clots, decidua, or both.

Sonography is an effective tool for evaluating postpartum patients thought to have retained placental fragments. Normal sonographic findings might obviate the need for manual exploration of the uterine cavity. A questionable sonographic result is not an effective tool for distinguishing between placental fragments and blood clots.