Fetal weight estimation by automated three-dimensional limb volume model in late third trimester compared to two-dimensional model: a cross-sectional prospective observational study

Comparison of diagnostic value of two-dimensional ultrasound and clinical examination in fetal weight estimation

Background:

Estimation of fetal weight during pregnancy plays an important role in prenatal and intrapartum care and is more important in pregnancies after 37 weeks to determine the type of delivery. The aim of this study was to compare and evaluate the accuracy and diagnostic value of two-dimensional ultrasound and clinical examination in estimating fetal weight and pregnancy outcomes.

Materials and Methods:

This cross-sectional study was conducted on 300 pregnant women without abnormal fetuses and pregnancies after 37 weeks; mothers who had a normal delivery or cesarean section were evaluated by the available method. The weight of the fetus was estimated before and after delivery, using ultrasound and clinical examination. Newborns were classified into five groups based on their fetal weight. Analysis of collected data was performed with SPSS software.

Results:

The mean age of the patients was 31 years and the mean weight of the neonates was 3450 g. At a weight of less than 3000 g, ultrasound and clinical evaluation were strongly correlated with the actual weight of the infant, but at weights of more than 3500 and 4000 g, weight estimation with ultrasound was highly accurate, and clinical examination had poor accuracy. In lower weights, square errors were fewer in both ultrasound and clinical examination, in comparison with higher weights. In higher weights, ultrasound is more reliable, and the diagnostic accuracy of clinical examination is reduced.

Conclusion:

Estimation of fetal weight with prenatal ultrasound is highly accurate. Clinical examination is more accurate in determining the weight of small fetuses and does not pay much attention to the diagnosis of macrosomic fetuses and even leads to overestimation, while ultrasound is much more accurate in diagnosing fetal macrosomia.

Comparison of two-dimensional (2D) and three-dimensional (3D) ultrasonography for gestational ageing in the early to mid-pregnant bitch

Accuracy of prediction of the day of parturition in the bitch decreases with advancing pregnancy. We hypothesized that three‐dimensional (3D) volume ultrasonography may be superior for gestational ageing than 2D measurements. Thirty‐two pregnancy examinations were performed in 25 bitches of different breeds 21–34 days after the first mating. Ovulation date from serum progesterone concentrations was estimated for 15 bitches, and parturition date was recorded for all dogs. Inner chorionic cavity (ICC) diameters and ICC length of the conceptus were measured by 2D B‐mode, and ICC volume by 3D ultrasonography (Voluson^® i, GE Healthcare). Linear or exponential regressions between ICC measurements and time, i.e. days after estimated ovulation or days before parturition, were performed with significance set at p < .05. ICC volume increased exponentially over time, while ICC diameter showed a linear growth. ICC volume had similar accuracy (R² = .718, p < .001) to ICC diameter and ICC length (R² = .707 and R² = .728, p < .001) when analysed in relation to days after estimated ovulation or in relation to days before parturition (R² = .818, R² = .800 and R² = .810, p < .001 respectively). There were strong (R² ≥ .875) significant associations between all ICC measurements. In conclusion, ICC volume did not improve canine gestational ageing accuracy, which supports the continued use of the ICC diameter, particularly in light of the difficulty in obtaining 3D measurements. On the basis of ICC volume, the growth of the canine conceptus appeared to be exponential already during the first half of pregnancy.