Quantificação do líquido amniótico pela ultra-sonografia tridimensional e bidimensional no primeiro trimestre da gestação Quantitation of amniotic fluid by three- and two-dimensional ultrasonography during the first trimester of pregnancy

Abstract

OBJETIVO: quantificar os valores do líquido amniótico no primeiro trimestre da gestação, em fetos normais, por meio de ultra-sonografia tridimensional e bidimensional. MÉTODOS: foram avaliados 25 fetos normais, da 8ª à 11ª semana de gestação. O estudo foi do tipo prospectivo longitudinal. As medidas do volume de líquido amniótico foram obtidas por meio de ultra-sonografia endovaginal, modos tridimensional e bidimensional. O estudo bidimensional consistiu em determinar o volume por cálculo matemático com base na forma de um elipsóide (constante 0,52), obtendo-se o volume do saco amniótico e do embrião. No estudo tridimensional, o volume do líquido amniótico foi feito pela técnica VOCAL, utilizando os graus de rotação 6, 9, 15 e 30°. Foi considerado como resultado final o volume do líquido amniótico obtido pelo grau de rotação6. Em ambos, o volume de líquido amniótico foi obtido pela subtração do volume do saco amniótico pela medida volumétrica do embrião. Para análise estatística utilizamos análise de variância (ANOVA), correlação e análise de regressão. O nível de significância adotado foi p PURPOSE: To determine the values of amniotic fluid in normal fetuses during the first trimester of pregnancy by three- and bi-dimensional ultrasonography. METHODS: In a prospective longitudinal study, 25 normal fetuses were evaluated from the 8th to the 11th week of gestation. Amniotic fluid volume was measured by endovaginal ultrasonography with the three- and two-dimensional modes. The two-dimensional study consisted of volumetric determination by mathematical calculation based on an ellipsoidal shape (constant 0.52) to obtain the amniotic sac and embryo volumes. In the three-dimensional study, the amniotic fluid volume was determined by the VOCAL technique using 6, 9, 15, and 30 degrees of rotation. The amniotic fluid volume obtained by 6-degree rotations was considered to be the final result. In both modes, amniotic fluid volume was obtained by subtracting the volume of the embryo from the volume of the amniotic sac. Data were analyzed statistically for variance (ANOVA), correlation and regression analysis. The level of significance was set at p < 0.05. RESULTS: The amniotic fluid volume as measured by two-dimensional ultrasonography increased from 5.45 to 39.52 cm³ in the range from the 8th to the 11th week (ANOVA - p < 0.05). There was a correlation between gestational age and amniotic fluid volume (p < 0.001, r² = 88.3%). In the three-dimensional study, the amniotic fluid volume increased from 5.7 to 42.9 cm³ in the range from the 8th to the 11th week (ANOVA - p < 0.05), and again a correlation between gestational age and amniotic fluid volume (p < 0.001, r² = 98.1%) was observed. CONCLUSION: an increase in amniotic fluid volume occurs during the first trimester of pregnancy, as determined by the two- and three-dimensional modes. In addition, we have demonstrated that the higher the gestational age, the larger the amniotic fluid volume.

Keywords

• Primeiro trimestre da gravidez
• Ultra-sonografia prenatal
• Líquido amniótico
• Ultrasonografia
• Pregnancy trimester, first
• Ultrasonography, prenatal
• Amniotic fluid
• Ultrasonography