Accuracy of the sonographic determination of estimated fetal weight in anhydramnios.

OBJECTIVE: To determine whether the presence of anhydramnios significantly influences the sonographic estimated fetal weight (EFW) compared to a matched cohort with normal amniotic fluid volume. METHODS: The study sample of this retrospective case-control study consisted of 114 pregnant women who presented to a Tertiary Perinatal Clinic between 2015 and 2020. 57 of them presented with an anhydramnios and a matched cohort of 57 women with normal amniotic fluid volume. At time of admission, gestational age varied between 22 + 4 and 42 + 6 weeks of pregnancy. All women underwent detailed ultrasound assessment for EFW and amniotic fluid index. To determine EFW Hadlock's estimation formula I was used which is based on measurements of biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). The EFW was compared with the weight at delivery. The maximum time interval between measurement and delivery was 5 days. RESULTS: There was neither a significant difference between the case and control group with regard to gestational age at ultrasound in days (median 249 days and 246 days, p = 0.97), nor to gestational age at birth (median 249 days and 247 days, p = 0.98). Concerning the newborns parameters, the body length at birth was not significantly different between the case and control group in centimeters (cm) (median 47 cm and 47 cm, p = 0.79). EFW in gram (g) was lower than birth weight in both groups and did not differ significantly between case and control group (estimated weight median 2247 g and 2421 g, p = 0.46; birth weight median 2440 g and 2475 g, p = 0.47). The difference between EFW and birth weight in percent (%) did not differ between the case and control group (median - 3.9% and - 5.6%, p = 0.70). The maternal parameters showed that the patients in the case group were younger (median 31 years and 38 years p = 0.20) and had a significantly higher body mass index (BMI) (median 27.3 kg/m2 vs 22.0 kg/m2, < 0.001) compared to the control group. CONCLUSION: Our study shows for the first time that EFW in women with anhydramnios can be determined sonographically just as accurately as in a matched cohort with normal amniotic fluid volume. A reliable estimation of fetal weight is crucial for optimal assessment of the newborns prognosis and counseling of the parents especially when advising women in the early weeks of pregnancy at the limit of viability.

Role of thigh circumference in predicting the fetal weight: Comparison with other ultrasound methods-A prospective observational study.

AIM: We aimed to evaluate the addition of fetal thigh circumference (TC) to other ultrasound parameters to predict fetal weight compared to two standard formulae (Hadlock's and Vintzileos methods). METHODS: We conducted this prospective study on pregnant women between November 2018 and September 2019. The actual fetal weight was estimated within 48 h of delivery; then, it was compared to the estimated fetal weight by ultrasound. We used the Statistical Package for the Social Sciences (SPSS) software version 20.0 to perform the statistical analysis. RESULTS: A total of 123 pregnant women, with a mean age of 26.68 (5.24) years and a mean gestational age of 38.78 (0.85) weeks, were included in our study. We detected a significant positive correlation between different ultrasound parameters and actual weight (all p ≤ 0.001). The highest correlation was observed between TC and actual fetal weight (r = 0.685). Regarding both formulae, the correlation coefficient was higher in the Vintzileos formula than the Handlock formula (0.976 vs. 0.823). Our linear regression analysis showed that fetal TC could be an indicator for estimating fetal weight (p < 0.001). There was a statistically significant difference between the actual weight and the weight estimated by the Hadlock formula (p < 0.001). We detected no statistically significant difference between the estimated TC by ultrasound and the actual TC (p = 0.0602). CONCLUSION: Fetal TC can help accurately measure fetal birth weight when incorporated with other fetal parameters. The inclusion of fetal TC assessment in routine ultrasound examination is suggested to improve the birth estimates.

Accuracy of sonographic fetal weight estimation prior to delivery in a Chinese han population.

OBJECTIVE: To compare the sonographic-estimated fetal weights (EFW) calculated with the Hadlock formula and with the Woo formula in a group of Chinese pregnant women. METHODS: We prospectively recruited term pregnancies for sonographic biometric examination. EFWs were calculated according to two formulas and compared with the corresponding birth weight (BW). We also assessed the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of EFW for the diagnosis of small-for-gestational age (SGA) and large-for-gestational age (LGA) neonates. RESULTS: A total of 374 subjects who delivered within 7 days after the sonographic examinations was recruited. Using the Hadlock formula, the median absolute difference between EFW and BW was 182 g (15-308 g) and the median percentage difference was 5.3% (0.5-9.1%), whereas it was 230 g (62-367) and 7.1% (2.1-10.4%) for the Woo formula (p < 0.001). Several factors, namely the fetal presentation, gender, and high amniotic quantity, showed no evident impact on this predictive difference. Among the 175 women who delivered within 2 days after ultrasound, the sensitivity and specificity of Hadlock EFW were 100% and 97.1% for the detection of SGA and 48.1% and 97.3% for the detection of LGA, respectively. The PPV and NPV were 44.4% and 100.0% for the detection of SGA and 76.5% and 91.1% for the detection of LGA, respectively. CONCLUSIONS: EFWs calculated using the Hadlock formula for our research subjects were as accurate as those reported for other populations. The predictive performance showed a high NPV for the diagnosis of SGA and a relatively acceptable PPV for the diagnosis of LGA. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:465-471, 2017.

Ultrasonographic fetal thigh measurement in the estimation of fetal weight based on Isobe's formula in women with an engaged fetal head in the pelvis: a comparative study.

PURPOSE: Because of the inaccuracy of the biparietal diameter in cases with an engaged fetal head in the pelvis, measuring the estimated fetal weigh (EFW) using Hadlock's formula could be compromised in these cases. The aim of this prospective study is to determine the accuracy of using only two thigh parameters, the femur length (FL) and the cross-sectional area of the thigh (CSAT) (Isobe's formula), in detecting the fetal weight of both engaged pelvis fetuses and non-engaged head fetuses and to compare this method with Hadlock's formula in both groups using the actual birth weight as a gold standard. METHODS: The study included 51 cases with an engaged fetal head and 51 cases with a non-engaged fetal head that came in active labour. 2D ultrasonography examination was performed to determine the EFW using both Hadlock's formula and Isobe's formula. The EFW was then compared with the actual birth weight after delivery. RESULTS: There was a strong positive correlation between Isobe's formula and the actual birth weight in the engaged fetal head group (r = 0.993, p < 0.01), but there was a strong positive correlation between Hadlock's formula and the actual birth weight in the non-engaged fetal head group (r = 0.994, p < 0.01). CONCLUSION: We concluded that Isobe's formula is convenient in predicting the fetal weight, especially when head measurements are difficult to assess (in the engaged fetal head group). It can be used with 2D ultrasonography as an alternative to Hadlock's formula in cases with an engaged fetal head in the pelvis.

[Chart for estimation of fetal weight 2014 by the French College of Fetal Sonography (CFEF)]. / Courbe d'estimation de poids fœtal 2014 par le Collège français d'échographie fœtale (CFEF).

OBJECTIVE: To establish a reference chart for estimated fetal weight (EFW) using the Hadlock formula based on recent biometric data (2012-2013). MATERIAL AND METHODS: A prospective multicentric longitudinal study was carried out. Biometric parameters as the head circumference (HC), abdominal circumference (AC) and the femur length were measured in multiple areas of France from January 2012 until December 2013. EFW was calculated using the predictive formula of Hadlock using three parameters. The accurate gestational age was the main inclusion criteria calculated in weeks of gestation (WG). A polynomial regression approach was used to calculate the mean and standard deviation for every WG adjusted to raw data. Centiles of EFW were calculated from the z score that corresponds to the -1.88, -1.28, 0, +1.28, +1.88 respectively for the 3rd, 10th, 50th, 90th, et 97th percentile in order to establish a new chart of EFW. RESULTS: Measurements were obtained for 33,143 fetus between 17 et 38 WG. Reference charts with the 3rd, 10th, 50th, 90th et 97th percentiles were presented. CONCLUSION: The reference Chart 2014 is an in utero chart for EFW based on ultrasound measurements data reliable and homogenous from a sample of 33,143 fetus of a general population. It offers a tool to use in routine ultrasound examination for the survey of the fetal growth and to diagnose fetus that are small for gestational age or presenting a restriction in growth.