Browsing by Author "Wanigasekara, R."

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Accuracy of ultrasound estimated fetal weight formulae to predict actual birthweight after 34 weeks: prospective validation study
(Sri Lanka Medical Association, 2013) Kumarasiri, S.; Wanigasekara, R.; Wahalawatta, L.; Jayasinghe, L.; Padeniya, T.; Dias, T.
OBJECTIVES: Late onset fetal growth restriction is often missed and is responsible for most intrauterine deaths. Ultrasound fetal biometry is routinely used to calculate estimated fetal weight (EFW). The aim of this study was to determine the accuracy of established ultrasound EFW formulae to identify small and large for gestational age fetuses when used after 35 weeks gestation. METHODS: This was a prospective validation study done between January 2012 and July 2012 at General Hospital Ampara. An ultrasound examination was performed and fetal biometry was documented within one week before the delivery in well dated pregnancies. The mean of the differences between ultrasound EFW derived from 9 formulae and true birthweight and their standard error of mean (SE) were calculated for each formula. Systematic measurement error was assumed to exist if zero lay outside the mean difference ± 2SE. To show the EFW frequency distribution, z-scores were calculated as the number of standard deviations an observed EFW measurement deviated from the mean for gestation. RESULTS: A total of 393 pregnancies at gestational age between 35 and 41 weeks were recruited. Mean gestational age at the ultra sound scan was 39.36 weeks SD (1.05). All EFW formulae either under or over estimated the birthweight in singleton pregnancies. Almost all the formulae over estimated the fetal weight in low birthweight babies whilst underestimating the fetal weight in birthweight >3500g. Campbell formula remained the only EFW formula without systematic error when measuring babies between 2500g and 3500g. None of the EFW z-scores were normally distributed. CONCLUSIONS: This study found that all routinely used EFW formulae would either over or under estimate the fetal weight. Until an optimum EFW formula that suits the Sri Lankan population is determined, interpretation of ultrasound EFW should be done cautiously, especially in small for gestational age babies
Risk of stillbirth at term and optimum timing of delivery in uncomplicated south Asian singleton pregnancies
(Sri Lanka Medical Association, 2014) Dias, T.; Kumarasiri, S.; Wanigasekara, R.; Cooper, D.; Batuwitage, C.; Jayasinghe, L.; Padeniya, T.
OBJECTIVES: Aims of this study were to compare the perinatal mortality rate and the prospective risk of stillbirth for each given gestational age and to ascertain whether it is safe to continue the pregnancy beyond 40 weeks of gestational age and induce labour at 41 weeks in low risk singleton pregnancies. METHODS: This was a retrospective study. The perinatal mortality and prospective risk were calculated per 1000 total births and 1000 on going pregnancies respectively in well dated singleton pregnancies. 38+0 to 39+6 gestational age was taken as the reference. RESULTS: A total of 12,595 deliveries after 28 weeks of gestation were included. The risk of stillbirth at 38+0 to 39+6 weeks was 1.43 (95% CI, 0.9 to 2.4) per 1000 on going pregnancies. The perinatal mortality rate at 38+0 to 39+6 weeks was 2.9 (95% CI, 1.9 to 4.5) per 1000 total births. The perinatal mortality rate decreased throughout gestation and it was lowest at 40+0 - 41+6. In contrast, risk of stillbirth increased with advancing gestation and peaked at 40+0 - 41+6 (2.57, 95% CI, 1.4 to 4.7). However, risk of stillbirth at 40+0 - 41+6 was not statistically different from 38+0 to 39+6 (OR 1.79, 95% CI, 0.80 to 3.98). To prevent one stillbirth, 886 pregnancies should be induced at 38+0 to 39+6. CONCLUSIONS: Risk of stillbirth is more informative than perinatal mortality at term. Frequent antenatal fetal surveillance should be adopted towardsterm in order to identify high risk pregnancies. Elective delivery before 40 weeks in low risk pregnancies is not justified