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.


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.


CONCLUSIONS
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.
Private Docents, Associate Professors, Obstetrics Department, Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM-Unifesp), São Paulo, SP, Brazil.
Luciano Marcondes Machado
LM
Nardozza
Master, Physician Assistant at Clínica Fetalmed, Curitiba, PR, Brazil.
Ana Paula
AP
Passos
Private Docents, Associate Professors, Obstetrics Department, Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM-Unifesp), São Paulo, SP, Brazil.
Edward
E
Araujo Júnior
PhD, Associate Professor, Gynecology and Obstetrics Department, Universidade Federal do Paraná (UFPR), Curitiba, PR, Brazil.
Rafael Frederico
RF
Bruns
Private Docent, Full Professor, Obstetrics Department, Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM-Unifesp), São Paulo, SP, Brazil.
Antonio Fernandes
AF
Moron
Cisterna magna; Fetus; Reference intervals; Three-dimensional ultrasonography; Two-dimensional ultrasonography