Evaluation and Significance of Nonvisualization of the Cavum Septum Pellucidum on Prenatal Ultrasonography.

Importance: The identification of the cavum septum pellucidum (CSP) is an integral part of the routine second trimester fetal anatomy scan. The absence or nonvisualization of the CSP has significant clinical implications and requires further evaluation and counseling for the pregnant patient.

Objective: The aim of this review is to review the importance of accurate sonographic identification of the CSP and the underlying pathologies that can be associated with nonvisualization of this structure.

Evidence acquisition: A literature review was performed with PubMed using key words including CSP, fetal anatomy ultrasound, and fetal anomalies.

Results: The absence of the CSP is associated with several central nervous system pathologies, all with a wide range of phenotypic outcomes, ranging from normal to very severe or lethal.

Relevance: Most obstetrician-gynecologists will have a patient in whom a CSP is not identified on fetal ultrasound. Thus, it is imperative to have a general understanding of this relatively common entity.