Ultrasound-Detected Placental Edematous Changes as Indicators of Unplanned Preterm Birth in Post-Fontan Pregnancies

Fontan surgery is a palliative procedure frequently performed for functional single-ventricle heart diseases. Fontan circulation is typified by increased central venous pressure and reduced cardiac output, which can lead to placental hypoxia and adverse obstetric outcomes. In post-Fontan pregnancies, ultrasonography may reveal abnormal placental appearances, also refer to as “ultrasonographic placental edematous changes”. Our focus has been on the increased occurrence of unexpected labor onset associated with these ultrasonographic findings. This study analyzed clinical charts and ultrasonograms between 2015 and 2022 and aimed to determine whether such findings could indicate a risk of premature delivery before scheduled dates in post-Fontan pregnancies.

The outcome of the study demonstrated:

The study included 15 patients.

• Ultrasonographic placental edematous changes were observed in eight cases (53%). 
• Among these, six patients (75%) experienced unexpected premature labor, with two resulting in vaginal deliveries due to sudden labor onset, while four required emergency cesarean sections. 
• Two patients had planned preterm cesarean deliveries.
• In contrast, all seven pregnancies without placental edematous changes resulted in deliveries on the pre-scheduled dates based on the maternal heart condition.

To conclude, unexpected preterm delivery is more likely to occur in pregnancies with ultrasonographic placental oedematous alterations than in those without. In post-Fontan pregnancies, ultrasound-detected placental oedematous alterations may be predictive indicators for unintended preterm births.

Source: Watanabe T, Shimada E, Yoshizawa S, Kakogawa J. Ultrasonographic placental edematous changes as predictive markers of unplanned preterm birth in post-Fontan pregnancies: A single-center observational study. J Obstet Gynaecol Res. 2024 Dec;50(12):2255-2262. doi: 10.1111/jog.16131. Epub 2024 Oct 22. PMID: 39438115.