OBJECTIVES: Fetal corpus callosal (CC) anomalies have been reported in the prenatal imaging literature since 1985, and especially when isolated, pose challenges for both the patient and fetal medicine specialist. The purpose of this study was to systematically review the literature on prenatally diagnosed abnormalities of the corpus callosum, focusing on the terminology used to describe abnormalities other than complete agenesis of the corpus callosum and review the heterogeneity of nomenclature and definitions in the prenatal literature.
METHODS: This study was conducted in accordance with the PRISMA statement for reporting systematic reviews. After performing the literature search and review, prospective or retrospective case series or cohorts reporting fetal imaging findings and describing anomalies of the corpus callosum were included in this review. Quality and risk of bias was evaluated using the NOS scale and a modification of the scale developed by Conde-Agudelo et al. for other fetal imaging studies. The data extracted included number of patients, number of different anomalies identified, descriptive name, and, where applicable, definitions of anomalies, number of cases of each type of anomaly, and biometric charts used. Secondary tests to confirm the diagnosis, as well postnatal or post-termination tests used to ascertain the diagnosis were also recorded.
RESULTS: The search strategy resulted in 998 titles and after review of titles, abstracts, limiting to English, French, Italian, German, or Spanish articles, and full review of 45 papers, 27 papers were initially included in the study, 24 of which were included in the final analysis. These 24 papers have a broad range of quality and risk of bias and represent 1135 cases of callosal anomalies of which 49% are complete agenesis and the remainder are described using the term partial agenesis or nine other terms, five of which have more than one definition.
CONCLUSIONS: Contrasting to the postnatal literature, in the prenatal literature there is a much greater heterogeneity in the nomenclature and definitions of callosal anomalies other than complete agenesis. This heterogeneity and lack of standard definitions in the prenatal literature make it difficult to develop large multi-centric pooled cohorts of patients who can be followed to develop better understanding of the genetic associations, neurodevelopmental, and psychological outcomes of patients with callosal anomalies. As this information is important to improve counselling these patients, a good first step towards this goal would be to develop a simpler categorization of prenatal callosal anomalies that better matches postnatal literature. This article is protected by copyright. All rights reserved.