The isolated mildly enlarged cisterna magna in the third trimester: much ado about nothing?

The Term Newborn: Postnatal Screening and Testing

Prenatal genetic screening, including evaluation for inherited genetic disorders, aneuploidy risk assessment, and sonographic assessment, combined with a thorough newborn examination and standard newborn screening, including blood, hearing, and congenital heart disease screening, can reveal conditions requiring further evaluation after delivery. Abnormal prenatal or newborn screening results should prompt additional diagnostic testing guided by maternal fetal medicine, perinatal genetics, or pediatric specialists.

Reference intervals of fetal cisterna magna volume by two-dimensional method using the multiplanar mode of three-dimensional ultrasonography

OBJECTIVE

To establish reference intervals for the fetal cisterna magna volume by means of two-dimensional (2D) method using the multiplanar mode of three-dimensional ultrasonography.

MATERIALS AND METHODS

Cross-sectional study with 224 healthy pregnant women between the 17th and 29th gestational weeks. The volume was automatically obtained by multiplying the three major axes in axial and sagittal planes by the constant 0.52. Polynomial regression was utilized to establish the correlation between fetal cisterna magna volume and gestational age, with adjustments by coefficient of determination (R(2)). Reliability and agreement were obtained by intraclass correlation coefficient (ICC) and limits of agreement, respectively.

RESULTS

Mean fetal cisterna volume with the 2D method ranged from 0.71 ± 0.19 cm(3) to 4.18 ± 0.75 cm(3) at the 17th and 29th weeks, respectively. The authors observed a good correlation between fetal cisterna magna volume and gestational age (R(2) = 0.67), excellent intraobserver reliability and agreement with ICC = 0.89 and limits of agreement 95% (-52.0; 51.8), respectively, and low interobserver reliability and agreement with ICC = 0.64 and limits of agreement 95% (-110.1; 84.6), respectively.

CONCLUSION

Reference intervals for fetal cisterna magna volume by means of 2D method using the multiplanar mode of three-dimensional ultrasonography were established and presented excellent intraobserver reliability and agreement.