Prenatal Diagnosis of Apparently Isolated Absence of the Septum Pellucidum: Literature Review and Presentation of a Rare Association With 15q13.3 Microduplication.

We conducted a focused review of prenatally diagnosed apparently isolated septum pellucidum agenesis with available follow-up. Across nine series including 112 fetuses, septal optic dysplasia (SOD) was ultimately confirmed in 21 cases (18.8%), but only 43% were suspected before birth, usually on the basis of optic nerve hypoplasia, while 57% were diagnosed postnatally. Truly isolated cases generally showed favorable neurodevelopment. Our accompanying case illustrates a rare association with 15q13.3 microduplication and highlights that prenatal suspicion of SOD may also arise from endocrine-related sonographic markers. These findings emphasize diagnostic challenges and the value of integrated imaging and genetics.