الفهرس 
Rationale of the StudyOnly 14 pages are availabe for public view
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Abstract
Objective: the aim of this work is assess the accuracy of measurements of fetal thigh circumference as a sonographic parameter in calculation of expected fetal weight.
Patients and methods: This is a cross-sectional diagnostic prospective study performed at Ain Shams University Maternity Hospital from October 2016 to May 2017, 228 pregnant women who met inclusion criteria and admitted for planned delivery at term (between 37-41 weeks) either be elective cesarean section or by induction of labour and vaginal delivery were subjected to history taking and ultrasound examination (fetal anatomy and fetal biometry: BPD, HC, FL, AC and TC) performed by an experienced sonographers using a Medison SonoAce R5 ultrasound machine. Counseling and verbal consent was taken before inclusion in the study. The estimated fetal weight (EFW) was be calculated by the formula of Hadlock et al based on BPD, HC, FL and AC and the formula of vintzileos et al based on BPD, AC, FL and TC. The newborns weighted after delivery within 24 hours and the actual birth weight compared to estimated fetal weight by ultrasound. Fetal weights are classified into low (<2500 gm), average (2500-4000) and macrosomia (>4000gm). Accuracy tested by correlating raw values of fetal weight by ultrasound (equations) with that of gold standard (postnatal weight). Different cut off points set for fetal weight to calculate different validation measures (sensitivity, specificity, PPV, NPV, likelihood ratio). P value, error value always set at 0.05, significant results declared if P value is less than 0.05. All data management performed using SPSS.
Results: The mean age of included women was 26.10±4.84 years (range: 18 -40 years). The median parity was 1 (range: 0 - 5); the mean gestational age was38.37±1.18 weeks (range:37 -41 weeks). Estimated fetal weight (EFW) using Hadlock’s formula revealed that the number of neonates had low birth weight was9 out of 228(3.95%) while the number of neonates had average birth weight was200 out of 228 (87.72%). On the other hand the number of neonates had macrosomia was 19 out of 228 (8.33%). Estimated fetal weight (EFW) using Vintzileos’ Formula revealed that the number of neonates had low birth weight was 11 out 228 (4.8%) while the number of neonates had average birth weight was 204 out of 228 (89.5%). Moreover the number of neonates had macrosmia was13 out of 228 (5.7%). Actual birth weight in the included women revealed that neonates had low birth weight was11 out of 228 (4.8%), the number of neonates had average birth weight was207 out of 228 (90.8%). Moreover the number of neonates had macrosmia was 10 out of 228 (4.4%). Correlation between Actual Birth Weight and Each of EFW (using Both Formulae) in included women revealed that there was a significant positive correlation between actual birth weight and each of EFW using Hadlock’s formula and EFW using Vintzileos’ formula. The higher correlation coefficient was with EFW using Vintzileos’ formula ]r=0.907, p<0.001[, indicating more significant association. Significant positive correlation between actual fetal birth weight with both EFW using Hadlock’s formula and EFW using Vintzileos’ formula in all categories of birth weights (low, macrosomia and average), their was more significant positive correlation between actual fetal birth weight and EFW using Vintzileos’ formula. Using Hadlock’s formula, the mean error (from actual birth weight) was 221.58±145.61 g. The mean absolute error percentage of the actual birth weight was 7.76±3.72. Of include women,163(71.5%) had their absolute error in Hadlock’s formula-EFW within 10% of the actual birth weight, while 65 (28.5%) had it more that 10% of the actual birth weight. Using Vintzileos’ formula, the mean error (from actual birth weight) was 57.73±99.77g. The mean absolute error percentage of the actual birth weight was 5.88±4.69.of the included women,176(77.2%) had their absolute error in vintzileos’ formula-EFW within 10% of the actual weight, while 52(22.8%) had it more that 10% of the actual birth weight.
Conclusion: It can be concluded that, based on this study thigh circumference has a role to play in accurately measuring fetal weight when incorporated with other fetal parameters. Vintzileos’ formula in this study would be useful in daily clinical practice for estimation of fetal weight, and may prove most useful in predicting fetal weight when growth abnormalities are present. Good correlation was found between prenatal and postnatal thigh circumference estimates & ultrasound can fairly reproduce the actual thigh circumference and its inclusion in routine ultrasound is strongly recommended to improve the birth estimates