Human Foetal Sacral Length Measurement for the Assessment of Foetal Growth and Development by Ultrasonography and Dissection

This study investigated the value of prenatal ultrasonographic measurements of sacrum as a predictor of in utero development and gestational age (GA), and to make a comparison between the data obtained by ultrasonography and dissection. A prospective cross-sectional study of ultrasonography was conducted in 186 pregnant women with uneventful single pregnancies. GA ranged from 14 to 40 weeks, and the relationships of sacrum length (SL) with GA, femur length (FL), biparietal diameter (BPD), head circumference (HC) and abdominal circumference (AC) were evaluated. In addition, the sacral bones of 101 spontaneously aborted foetuses aged from 13 to 39 weeks were dissected and measured. The relationship of the results with GA was investigated. There was a linear relationship between the ultrasonographic measurements of the SL and the GA (R2 = 0.93, P < 0.001), the FL (R2 = 0.93, P < 0.001), the BPD (R2 = 0.93, P < 0.001), the HC (R2 = 0.92, P < 0.001) and the AC (R2 = 0.90, P < 0.001). The rate of increase of SL was significantly higher before 28 weeks of gestation than in later pregnancy, with a correlation coefficient between SL and GA of 0.96 and 0.88, respectively. The SL measurements obtained by dissection were similar to those of ultrasonography. There was a linear relationship between the SL and the GA (R2 = 0.96, P < 0.001) and the correlation coefficients between SL and GA were 0.97 before 28 weeks of gestation, and 0.94 in later weeks. In conclusion, this study demonstrates a high correlation between the SL, GA and other standard measurements of foetal growth, and suggests that SL measurement is a valuable predictor of GA in the foetuses with normal growth.