RATIO OF CHOROID-PLEXUS CIRCUMFERENCE TO VENTRICULAR CIRCUMFERENCE INTHE DIAGNOSIS OF FETAL HYDROCEPHALUS

OBJECTIVE: To establish normative measures of the biologic growth of f etal choroid plexus circumference (CPC) and ventricular circumference (VC) in normal pregnant women. STUDY DESIGN: We studied 185 women with uncomplicated pregnancies ranging in gestational age from 14 to 26 we eks and undergoing ultrasound examination for genetic amniocentesis. C PC and VC were measured with a transverse scan of the fetal head to es tablish normative values. Following establishment of CPC/VC ratios for normocephalic fetuses, an additional eight fetuses with suspected ven triculomegaly at the time of routine ultra-sound were scanned. RESULTS : Of the 185 fetuses for normal pregnancies who met the criteria for t his study, all were normocephalic at birth. Of the eight fetuses who w ere suspected to have ventriculomegaly on ultrasound, all were diagnos ed as moderately to severely hydrocephalic on autopsy after second-tri mester termination. CONCLUSION: The CPC/VC ratio is able to unequivoca lly distinguish between the overtly hydrocephalic and normocephalic fe tus. The results of this study suggest that CPC and VC measurements ma y be valuable wizen hydrocephalus is suspected and there are equivocal ventricular/hemispheric width measurements.