CEREBELLAR DOPPLER VELOCIMETRY IN THE APPROPRIATE-AGE AND SMALL-FOR-GESTATIONAL-AGE FETUS

Objective: To compare superior cerebellar artery now velocity waveform s in the appropriate-for-gestational-age (AGA) and the small-for-gesta tional-age (SGA) fetus. Methods: Superior cerebellar artery velocity w aveforms were obtained prospectively from 172 AGA fetuses at 17-41 wee ks' gestation. The pulsatility index (PI) was used to quantify the wav eforms. Superior cerebellar artery velocity waveforms were also obtain ed from 30 SGA fetuses divided into group A (n = 15), with a normal um bilical artery PI, and group B (n = 15), with an abnormal umbilical ar tery PI. The transverse cerebellar diameter was measured in all SGA fe tuses. Results: The superior cerebellar artery PI was best represented by a second-order polynomial equation [PI = 0.145 + 0.101 x (gestatio nal age) - 0.00197 (gestational age)(2)]. Small-for-gestational-age fe tuses of group A had a superior cerebellar artery PI in the normal ran ge, whereas 13 of 15 fetuses of group B (86.7%) had a PI value less th an the individual 95% confidence interval. The transverse cerebellar d iameter in group A fetuses was in the normal range in ten of 15 cases, whereas it was in the normal range for all group B fetuses. Conclusio n: Small-for-gestational-age fetuses with an abnormal umbilical artery PI have ''cerebellar-sparing effect,'' as suggested by a superior cer ebellar artery PI less than the normal range and a normal transverse c erebellar diameter.