TRANSVERSE CEREBELLAR DIAMETER IN SMALL-FOR-GESTATIONAL-AGE FETUSES -PREGNANCY DATING IS POSSIBLE ONLY WHEN GROWTH-RETARDATION IS SECONDARY TO UTEROPLACENTAL INSUFFICIENCY

The objective of this study was to establish whether measurement of th e transverse cerebellar diameter to determine gestational age differs in small-for-gestational-age fetuses with normal or abnormal Doppler v elocity waveforms. Our secondary objective was to compare the efficacy of measurement of transverse cerebellar diameter with that of femur l ength in pregnancy dating among small-for-gestational-age fetuses. A t otal of 107 small-for-gestational-age fetuses with established dates a nd free from structural and chromosomal abnormalities were considered for this study. According to the Doppler results, fetuses were divided into two groups: group A (n = 64), with normal Doppler values as expr essed by a ratio of pulsatility indices between the umbilical artery a nd middle cerebral artery of less-than-or-equal-to 95th centile of our reference limits for gestation; and group B (n = 43), with ratio of > 95th centile. Measurements of transverse cerebellar diameter and femu r length were compared to previously established 95th centile predicti on intervals. In both groups of small-for-gestational-age fetuses, the values for transverse cerebellar diameter were lower than in normally grown fetuses after normalization for gestational age. The difference was more evident in group A (p less-than-or-equal-to 0.001) than in g roup B (p less-than-or-equal-to 0.05). Only 68.7% of transverse cerebe llar diameter values of group A fetuses fell within the normal limits for gestation, while this occurred in 90.6% of group B fetuses. When c ompared to the femur length, the transverse cerebellar diameter measur ement appeared to be better for predicting gestational age in both gro ups of small-for-gestational-age fetuses (p less-than-or-equal-to 0.00 1). However, this measurement may be used to estimate gestational age only in small-for-gestational-age fetuses with abnormal Doppler findin gs.