Association between first-trimester ultrasound imaging of eccentric implantation and retained placenta

To evaluate first-trimester ultrasound imaging of eccentric implantation in predicting the probability of retained placenta.

A total of 61 cases with gestational sac eccentrically implanted in first-trimester ultrasound imaging was selected. Demographic and obstetric data were collected through data extraction of the electronic medical record at the time of delivery admission. Baseline characteristics (including age, gestational age of first-trimester ultrasound, size of gestational sac, gestational age of delivery), delivery outcomes (mode of delivery, retained placenta or placental fragments, blood loss, postpartum hemorrhage and postpartum ultrasound imaging) were collected and analyzed.

The risk difference for a woman with eccentric implantation to have a retained placenta was -0.18 (95% CI -0.28 to -0.08, p = 0.000) and the incidence of retained placenta in the study group was higher than in the control group (18% vs. 0%, p = 0.006). First-trimester ultrasound imaging of eccentric implantation was also found to be an independent risk factor for the incidence of inhomogeneous mass in postpartum ultrasound imaging (27.9% vs. 10.8%, adjusted OR 0.19, 95% CI 0.05 to 0.79, p = 0.012). Though 2 cases in the study group suffered postpartum hemorrhage, the risk difference for a woman with eccentric implantation to suffer postpartum hemorrhage was -0.03 (95% CI -0.08 to -0.01, not significant) and eccentric implantation did not increase postpartum hemorrhage rates (3.3% vs. 0%, not significant).

First-trimester ultrasound imaging of eccentric implantation was associated with an increased risk of retained placenta and inhomogeneous mass in postpartum ultrasound imaging.