Evaluación de los índices biométricos fetales para el diagnóstico del Retardo del Crecimiento Fetal

Abstract

BACKGROUND: Fetal Growth Restriction occurs when a fetus does not reach its intrauterine growth potential due to genetic and/or environmental factors; it is associated with increased perinatal mortality and morbidity and also predisposes to the development of chronic disorders in adulthood. The aim of this study was to evaluate the accuracy of the Biometric Indices: Femur Length/Abdominal Circumference (FL/AC); Transverse Cerebellar Diameter/Abdominal Circumference (TCD/AC) and Humerus, Cerebellum, Femur/Abdominal Circumference Equation (HCF/AC); in predicting fetal growth retardation. METHODS: Diagnostic tests validation study, with a universe of pregnant patients who attended the outpatient clinic of Hospital General Machala, El Oro-Ecuador, for prenatal control, between 32 and 38 weeks of gestation. The following variables were obtained: gestational dating; ultrasound fetal biometry of all the necessary parameters for the described indices calculation; fetal weight estimated by ultrasound, with cut-off point ≤ P° 10. The LH/CA and TCD/CA Indices were calculated, with cut-off points for fetal growth retardation diagnosis of ≥ 23.5 and ≥16.1 respectively. The index proposed by the authors HCF/CA was also applied, taking as cut-off point the 90th percentile: ≥ 1.063. RESULTS: The prevalence of fetal weight less P° 10 in the present study was 12.22%. The biometric index with the highest sensitivity was the HCF CA index with 70.3%; however, the highest specificity was obtained for the LF CA index with 84%. The positive predictive value of the DTC CA index was 24.7%, of the LF CA index: 27.9%, and of the HCF CA index: 31.1%. The negative predictive values found were, DTC CA: 93.9%; LF CA: 91.6% and HCF CA: 95.0%. The positive likelihood ratios obtained were: DTC CA: 2.352; LF CA: 2.781 and HCF CA: 3.25. The negative likelihood ratios were, HCF CA: 0.378, DTC CA: 0.465, LF CA: 0.661. CONCLUSION:The biometric indices for prediction of fetal growth retardation have limited positive predictive accuracy. All indices have high negative predictive accuracy. To confirm the presence of condition disease the HCF CA index has better results, as well as to confirm the absence of the condition disease; the addition of the HCF CA Index increases the predictive results; the Odds Rate obtained indicates that there is 8.595 times higher probability of a positive response, when the condition"fetus in percentile ≤ 10" is present.