Placental Sonomorphologic Appearance and Fetomaternal Outcome in Fontan Circulation

<b>Objectives:</b> Pregnancies in women with Fontan circulation are on the rise, and they are known to imply high maternal and fetal complication rates. The altered hemodynamic profile of univentricular circulation affects placental development and function. This study describes placental sonomorphologic appearance and Doppler examinations and correlates these to histopathologic findings and pregnancy outcomes in women with Fontan circulation. <b>Methods:</b> A single-center retrospective analysis of pregnancies in women with Fontan circulation was conducted between 2018 and 2023. Maternal characteristics and obstetric and neonatal outcomes were recorded. Serial ultrasound examinations including placental sonomorphologic appearance and Doppler studies were assessed. Macroscopic and histopathologic findings of the placentas were reviewed. <b>Results:</b> Six live births from six women with Fontan physiology were available for analysis. Prematurity occurred in 83% (5/6 cases) and fetal growth restriction and bleeding events in 66% (4/6 cases) each. All but one placenta showed similar sonomorphologic abnormalities starting during the late second trimester, such as thickened globular shape, inhomogeneous echotexture, and hypoechoic lakes, resulting in a jelly-like appearance. Uteroplacental blood flow indices were within normal range in all women. The corresponding histopathologic findings were non-specific and consisted of intervillous and subchorionic fibrin deposition, villous atrophy, hypoplasia, or fibrosis. <b>Conclusions:</b> Obstetric and perinatal complication rates in pregnancies of women with Fontan circulation are high. Thus, predictors are urgently needed. Our results suggest that serial ultrasound examinations with increased awareness of the placental appearance and its development, linked to the Doppler sonographic results of the uteroplacental and fetomaternal circulation, may be suitable for the early identification of cases prone to complications.