The Accuracy of Multiple Sonographic Parameters in Estimation of Fetal Weight in Pregnant Sudanese Women Presenting to the Ribat University Hospital, Khartoum (December 2003 – May 2004).

Abstract

Ultrasonography has proved to be an accurate, safe, fast, reliable and cost effective imaging modality for the estimation of fetal weight at term. This study was carried out at the Ribat university hospital at Burri, Khartoum from December 6, 2003 to May 3, 2004 to evaluate the relative accuracy of three ultrasonographic formulas in estimating fetal weight in term Sudanese ladies. 200 pregnant ladies, aged between 18 and 42 years, were examined sonologically by a senior radiologist using an Aloka SSD- 650 real time scanner and the fetal weights were calculated using the Aloka formula A, Aoki’s formula and Shephard’s formula. 36.5 % of the study population were primigravidas and the rest were parous women. The mean gestational age at delivery was 39.5 ± 1.4 weeks while 11.5 % of the deliveries occurred after more than 40 weeks of gestation ( post term) 41.0 % of the ladies delivered on the same day of sonological examination, 45.0 % delivered one day after examination while 14.0 % delivered two days after examination. The study found that the birth weights of 93.0 % of the newborn babies were within the reference weight of 2500 – 4000 grams. Only 4.0 % of the newborns have low birth weights ( below the 10th percentile) while 3.0 % were macrosomic ( above 90th percentile). 54.5 % of the newborn babies were of male gender compared with 45.5 % female babies. The mean birth weight for the study population was found to be 3196.70 ± 454.16 grams. Male newborns had a higher mean birth weight (3281 ± 664.308 grams) compared to newborn girls whose mean birth weight was 3107 ± 635.077 grams. Two of the evaluated formulas, Aoki’s and Shephard’s formuals tended to underestimate fetal weights while the third formula, the Aloka formula gave estimates higher than the mean actual birth weight. However, all three evaluated formulas were found to be accurate for estimation of fetal birth weight in Sudanese ladies. The Aoki formula had the highest degree of accuracy with 77.0 % of its estimates falling within 10.0 % of actual birth weights. The Shephard equation was next with 76.0 % of its estimates within 10.0 % of actual birth weighs while Aloka’s equation predicted 75.5 % of the fetal weights within 10.0 % of actual birth weights. The Aoki formula also had the smallest mean error among the three evaluated formulas and has been recommended for use by the Sudanese obstetricians.