2D visualization and measurement of the fetal optic chiasm. Improving the counselling of antenatal diagnosis of agenesis of the septi pellucidi.

Viñals, F; Ruiz, P; Correa, F; Pereira, P

http://hdl.handle.net/10400.10/1775

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Ultrasound Obstet Gynecol. 2016 Jan 18.pdf		1.48 MB	Adobe PDF	Download

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Abstract(s)

To develop an objective method to visualize and measure the optic chiasm (OC) through a 2D coronal vaginal plane and to report measurements in fetuses with agenesis of the septi pellucidi (SP). METHODS: This was a prospective cross-sectional study of 115 morphologically normal fetuses in low-risk pregnancies, between 21 and 30 weeks' gestation. OC was measured in a coronal plane at the level of the third ventricle and was seen as a horizontally aligned dumbbell-shaped structure of moderate echogenicity. In addition, OC measurements from eight fetuses with agenesis of the SP and complete follow-up were compared to the reference range. RESULTS: OC measurements were obtained in 110 of 115 normal fetuses. OC growth occurred linearly with gestational age. Our method demonstrated good intraobserver repeatability and excellent interobserver reproducibility. Among the eight fetuses with agenesis of the SP, four had normal measurements, and five normal vision postnatally. Pregnancy continued to term in all cases and the follow-up period varied from six months to seven years. CONCLUSION: Our study demonstrates that it is possible to visualize and measure the OC directly through a 2D ultrasound coronal plane. In fetuses with agenesis of the SP, the morphology and width of the OC visual pathway could prove a relevant tool in assessing its development. It would also provide support to the difficult antenatal counselling when faced with the diagnosis of agenesis of the SP.