Ultrasonographic Evaluation of Infratentorial Brain Structures in Fetuses With Congenital Heart Disease: A Prospective Case-Control Study.

OBJECTIVES

To investigate the dimensions of infratentorial brain structures in fetuses with prenatally diagnosed congenital heart disease (CHD) and determine whether these measurements differ based on the expected pattern of fetal brain oxygen delivery.

METHODS

This prospective case-control study was conducted at a tertiary perinatal center. A total of 112 singleton pregnancies between 28 and34 weeks of gestation were enrolled, comprising 56 fetuses with CHD and 56 healthy controls. CHD cases were classified into 2 groups based on expected fetal brain oxygen delivery: Class A (n = 29, expected oxygen supply) and Class B (n = 27, expected normal oxygen supply). Detailed neurosonographic evaluation was performed using standardized protocols to measure infratentorial structures including cerebellar vermis (craniocaudal diameter [CCD], anteroposterior diameter [APD], circumference, and area), trans-cerebellar diameter, and brainstem structures (pons, midbrain, and medulla oblongata APDs). Maternal demographic characteristics, pregnancy course, and outcomes were retrieved from the hospital database.

RESULTS

Demographic characteristics were comparable between groups except for gestational age at delivery (38.23 ± 1.41 versus 38.87 ± 1.19 weeks, p = .011) and birth weight (3121 ± 477 g versus 3336 ± 318 g, p = .006), which were significantly lower in the CHD group. Fetuses with CHD demonstrated significantly smaller vermis CCD (Class A: 19.3 ± 1.65 mm, Class B: 19.2 ± 1.39 mm versus Controls: 20.6 ± 0.84 mm, p = .001) and vermis area (Class A: 2.70 ± 0.07 cm2, Class B: 2.71 ± 0.11 cm2 versus Controls: 2.86 ± 0.24 cm2, p = .001). Brainstem measurements revealed significantly reduced pons APD (Class A: 12.2 ± 1.62 mm, Class B: 12.1 ± 1.10 mm versus Controls: 13.4 ± 1.45 mm, p = .001) and medulla oblongata APD (Class A: 8.4 ± 0.87 mm, Class B: 8.3 ± 0.98 mm versus Controls: 9.2 ± 0.96 mm, p = .001). Trans-cerebellar diameter, vermis APD, vermis circumference, and midbrain APD showed no significant differences between groups. Importantly, no significant differences were observed between Class A and Class B CHD groups for any measured parameter.

CONCLUSION

Fetuses with CHD exhibit significant reductions in specific infratentorial brain measurements, including cerebellar vermis dimensions and brainstem structures (pons and medulla oblongata), compared to healthy controls. These abnormalities are present regardless of the CHD classification based on expected cerebral oxygen delivery, suggesting that the impact of CHD on fetal brain development is more complex than previously understood. These findings support the implementation of comprehensive neurosonographic evaluation in all fetuses with CHD and highlight the need for further research correlating prenatal infratentorial measurements with long-term neurodevelopmental outcomes.