Sonographic diagnosis of intrauterine growth restriction (IUGR) by fetal transverse cerebellar diameter (TCD) /abdominal circumference (AC) ratio

Objective: To evaluate the validity of TCD/AC ratio in predicting IUGR. Stu dy design: Prospective descriptive analysis. Setting: Maharaj Nakorn Chiang Mai Hospital, Chiang Mai University. Subjects: Women meeting the inclusion criteria consisting of: (1) singleton pregnancies after 28 weeks of gestat ion; (2) known accurate gestational age; and (3) clinically suspected IUGR. Methods: The patients were sonographically examined for TCD/AC ratio. The best cut-off value of TCD/AC ratio in predicting IUGR was determined by a r eceiver operating characteristic (ROC) curve. The fetus with a TCD/AC ratio greater than the cut-off value would be antenatally diagnosed as IUGR for every gestational week. Standard definition of IUGR was a low birthweight, less than the 10(th) percentile. Results: One hundred and sixty-seven pregn ancies with suspected IUGR were analyzed. The prevalence of IUGR among the study group was 51.5%. The best cut-off value of the TCD/AC ratio for predi cting IUGR was 15.4%, giving the sensitivity, specificity, positive predict ive value and negative predictive value of 73.26%, 80.25%, 79.75%, and 73.8 6%, respectively. Conclusion: The sonographic fetal TCD/AC ratio as a gesta tional age-independent method can be helpful in antenatal diagnosis of IUGR , especially in pregnancy with uncertain gestational age. (C) 1999 Internat ional Federation of Gynecology and Obstetrics.