Diagnosis of fetal growth restriction by transverse cerebellar diameter/abdominal circumference ratio - Revista Brasileira de Ginecologia e Obstetrícia

PURPOSE: to evaluate the validity of transverse cerebellar diameter (TCD)/abdominal circumference (AC) ratio in the diagnosis of fetal growth restriction (FGR), determining its best cutoff value and accuracy in symmetric and asymmetric FGR. METHOD: a prospective cross-sectional study, carried out in 250 pregnant women with singleton pregnancies, gestational age between 20 and 42 weeks, with ultrasound confirmation. The TCD measurement was obtained by placing the calipers at the outer margins of the cerebellum, after its localization in the posterior fossa, and slightly rotating the transducer below the plane of the thalami. The abdominal circumference was measured at the on junction of the left portal and umbilical veins. The best TCD/AC cutoff ratio was established by the receiver operator characteristic (ROC) curve. Neonates with TCD/AC ratio greater than the cutoff value were diagnosed as having FGR. We classified as gold standard for FGR the newborn infants who presented birth weight below the 10th percentile. Neonates showing FGR and Rohrer ponderal index between 2.2 and 3 were labeled as symmetric and below 2.2, asymmetric. RESULTS: the cutoff value calculated by the ROC curve for TCD/AC ratio was 16.15. The sensitivity, specificity, accuracy, positive and negative predictive values, and likelihood ratio for positive and negative tests were 77.4, 82.6, 38.7, 96.3, 82, 4.5 and 3.7%, respectively. In the symmetric FGR, sensitivity and specificity were 80.8 and 81.7%, respectively. In the asymmetric FGR, sensitivity and specificity were 60 and 75%, respectively. CONCLUSION: TCD/AC ratio is an effective method in symmetric and asymmetric FGR diagnosis.