FETAL TRANSVERSE CEREBELLAR DIAMETER ABDOMINAL CIRCUMFERENCE RATIO INASSESSING FETAL SIZE

Objective: To test the usefulness of the fetal transverse cerebellar d iameter/abdominal circumference (TCD/AC) ratio in predicting known sma ll-for-gestational-age (SGA) infants. Method: The relationship between fetal TCD and AC throughout the second half of pregnancy was investig ated in 635 well-dated, normal pregnancies and examined with regard to gestational age and infant birth weight percentiles. Results: One hun dred eighteen (19%) fetuses were excluded due to inadequate visualizat ion of the fetal cerebellum. A strong correlation was noted between ge stational age determined by the last menstrual period and both fetal T CD (r(2) = 0.91338) and AC (r(2) = 0.89361) in fetuses with birth weig hts between the 10th and 90th percentiles (n = 407; mean 14.4, S.D. 1. 2). Although the TCD/AC ratio showed a poor correlation with gestation al age (r(2) = 0.15788), a slight increase was noted during gestation. A TCD/AC ratio greater than 15.5 was present in 80% of SGA infants wh en measurements were performed within 1 week of delivery. Conclusion: Fetal TCD/AC ratio as a gestational age-independent method could impro ve diagnostic sensitivity and specificity in the early detection of fe tal growth-abnormalities.