Introduction: Counseling for fetal callosal abnormalities remains very challenging. Prenatal genetic testing and fetal MRI including an imaging-based scoring system (Diogo et al, 2021) can aid in counseling of parents regarding outcome. Aim of this study was to investigate the value of these techniques on parental decision making. Methods: A single center, retrospective case series study. When fetal callosal abnormalities were detected on prenatal ultrasound, parents were offered genetic testing (chromosomal microarray (CMA), exome sequencing (ES)) and/or fetal MRI. Results: Forty-nine fetuses were included. Partial agenesis of the corpus callosum (ACC) was detected in 28% of cases (6% isolated and 22% complex), complete ACC in 60% (27% isolated and 33% complex), a too thick CC, a dilated cavum septum pellucidum vergae (CSPV) and agenesis of the CSP in each 4% of cases. Genetic testing was performed in 86% of cases: a genetic diagnosis was established in 60% (24% with CMA, 76% with ES). Fetal MRI was performed in 30% of cases: 60% had a high (abnormal) imaging score. A genetic diagnosis and/or high imaging score was very helpful in parental decision making: 67% decided to continue pregnancy in case of normal genetic results and absence of high imaging score; 96% of parents opted for TOP or IUFD occurred, when abnormal genetic results and/or high imaging score were present. Conclusion: We show that genetic testing and/or fetal imaging score had a high impact on parental decision making. This warrants implementation in the routine care in fetal callosal abnormalities.

Cacha Peeters
Leiden University Medical Center
Netherlands

Marieke Veenhof
Leiden University Medical Center
Netherlands

Phebe Adama van Scheltema
Leiden University Medical Center
Netherlands

Joanne Verweij
Leiden University Medical Center
Netherlands

Menno Toirkens
Leiden University Medical Center
Netherlands

Mariette Hoffer
Leiden University Medical Center
Netherlands

Esther NIbbeling
Leiden University Medical Center
Netherlands

Emilia Bijlsma
Leiden University Medical Center
Netherlands

Gijs Santen
Leiden University Medical Center
Netherlands