(769) Contrast-enhanced ultrasound to characterize postpartum uterine circulation with placenta in situ for placenta accreta spectrum

Alternate methods of management for placenta accreta spectrum (PAS) include leaving the placenta in situ postpartum until interval hysterectomy or placental resorption/expulsion; descriptions of placental vascular changes in this subset of patients are limited. Color Doppler mapping of the placenta is often used, but is suboptimal at characterizing slow-moving vasculature. The use of ultrasound (US) contrast agents (UCA) may enhance visualization of placental flow.  We used UCA to identify vascular changes over time in the uteroplacental interface in patients with placenta in situ after cesarean delivery (CD) for PAS.

Study Design:

This was a case series of 5 patients suspected of having PAS based on US findings. Each patient underwent CD and retained the placenta with a plan for interval hysterectomy or awaiting placental resorption/expulsion. In patients opting for uterine preservation, contrast-enhanced ultrasound (CEUS) was performed once the uterus appeared to have minimal vascularity on color Doppler sonography. In patients opting for interval hysterectomy, CEUS was performed at the final pre-operative US. UCA (Lumason® (sulfur hexafluoride lipid-type A microspheres)) was administered intravenously and US images were obtained every 10 seconds using a combination of grayscale, color Doppler, and B-mode techniques until UCA disappearance.

Results:

CEUS was performed at 4.3, 5.9, 7.1, 9.1, and 14 weeks postpartum (PP). Uterine circulation enhancement was mainly seen using B-mode technique within 1 minute of UCA administration. UCA remained stable for 8-10 minutes, followed by a signal reduction. Representative images of CEUS are shown in Figure 1; CEUS findings are summarized in Table 1.

Marked vascularization was seen in the uterus and placenta 4-5 weeks PP. After 7.1 weeks PP, a significant reduction in blood flow to the placenta can be observed, with absence of placental blood flow by 14 weeks PP.

Conclusion:

UCA can be used to aid in visualization of uteroplacental perfusion. When the placenta is left in situ PP for PAS, vascularity begins to decrease at approximately PP week 7.