The ratio of cavum septi pellucidi width to anteroposterior cerebellar diameter: A novel index as a diagnostic adjunct for prenatal diagnosis of trisomy 18

Abstract

Aim To explore the effectiveness of cavum septi pellucidi (CSP) width to anteroposterior cerebellar diameter (APCD) ratio as a diagnostic adjunct for prenatal diagnosis of trisomy 18. Methods Images of normal fetal brain within 15 and 35 weeks were stored in our center from 2016 to 2017. Images of aneuploid fetuses were retrospectively collected from 2004 to 2017. The transverse cerebellar diameter, APCD and CSP width were measured. CSP/APCD and APCD/transverse cerebellar diameter ratios were calculated and compared between euploid and aneuploid fetuses. Results One thousand and forty one fetuses were analyzed, including 817 euploid fetuses and 224 aneuploid fetuses (trisomy 21 117 cases, trisomy 18 82 cases, trisomy 13 9 cases, sex‐linked 16 cases). No correlation had been found between both ratios and gestational weeks (P > 0.05). In aneuploid groups, means of ratios were both significantly different just between trisomy 18 group and euploid group (P < 0.05). The best area under the curve was shown by the CSP/APCD ratio. The cutoff value of CSP/APCD was 0.46 (sensitivity 87.0%, specificity 85.0%). Conclusion A wide CSP or cerebellar hypoplasia warrants a more detailed ultrasound screening and genetic counseling. A larger CSP/APCD ratio alerts us to trisomy 18 syndrome, especially in cases with subtle anomalies.

Reference Ranges for Corpus Callosum and Cavum Septi Pellucidi Biometry on Prenatal Ultrasound: Systematic Review and Meta‐Analysis

“…Of the 32 papers, 6 were excluded from further review. The remaining 26 articles 4–13,15,17,18,20–22,24,25,27,30,31,33,44,45 were reviewed qualitatively (Tables 1 and 2) and of these, 10 were included for quantitative review 4,5,7,9,12,15,21,24,30,33 . We contacted the corresponding author of all of the articles excluded for quantitative review due to the way in which the data were reported (eg, only graphically or not reported by gestational age); however, only one author sent us data suitable for analysis 24 …”

“…The remaining 26 articles [4][5][6][7][8][9][10][11][12][13]15,17,18,[20][21][22]24,25,27,30,31,33,44,45 were reviewed qualitatively (Tables 1 and 2) and of these, 10 were included for quantitative review. 4,5,7,9,12,15,21,24,30,33 We contacted the corresponding author of all of the articles excluded for quantitative review due to the way in which the data were reported (eg, only graphically or not reported by gestational age); however, only one author sent us data suitable for analysis. 24 Characteristics of Studies Included for Quantitative Synthesis: CC There were seven included articles for the CC, of which two and five used 3D and 2D measurements, respectively.…”

“…There was only one article suitable for metaanalysis of the CSP width in 2D, and one for 3D, precluding meta-analysis of the measurements for this important structure. 4,15…”

“…A large number of published nomograms exist for both CSP and CC biometry on prenatal ultrasound 4–33 . However, many of these studies have small sample sizes, unclear measurement techniques, or unconventional reporting standards.…”

Comparison of Cavum Septum Pellucidum Size in Euploid and Aneuploid Fetuses

“…A recent study examined the efficacy of the ratio of CSP width to anterior-posterior cerebellar diameter (APCD) as a diagnostic tool for prenatal trisomy 18 diagnosis. 22 A higher CSP/APCD ratio would support the diagnosis, especially in cases with trisomy 18 syndrome with few abnormalities. The strength of our study is that we have presented the CSP width/BPD ratio, a new practical and gestational weekindependent marker to predict aneuploidy.…”