Isolated Narrow Cavum Septum Pellucidum in Fetuses: A Variation of Normal Development.

Objectives: This retrospective study aimed to describe the outcome of a cohort of fetuses with isolated narrow cavum septum pellucidum (CSP), as identified by ultrasound (US) during the second or third trimester.

Methods: We reviewed the records of all patients referred for CSP abnormalities and identified those fetuses diagnosed with isolated narrow width of CSP (<3 mm) on US.

Results: The study population comprised 79 patients with isolated narrow CSP. 36 (36/79, 45.6%) underwent MRI, and a normal corpus callosum was observed in 34 (34/36, 94.4%) cases. Partial agenesis of the corpus callosum was diagnosed in the remaining two (2/36, 5.6%) cases. In addition, no pathological findings were reported in non-invasive prenatal testing NIPT (n = 47) and in amniocentesis (n = 11). A total of 33 (33/79, 41.8%) pregnant women gave birth at our institution, with an average Apgar score of 8-9. Neurodevelopmental outcome was available for 24 cases at a mean age of 31.6 ± 18.4 months, all of which were normal.

Conclusions: Almost all fetuses with isolated narrow CSP have a normal corpus callosum, and the neurodevelopmental outcome of these fetuses is generally good. Thus, isolated narrow CSP in the fetus can be considered a variation of normal development.