Ratio of choroid plexus circumference to ventricular circumference in the diagnosis of fetal hydrocephalus.

OBJECTIVE

To establish normative measures of the biologic growth of fetal 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 weeks and undergoing ultrasound examination for genetic amniocentesis. CPC and VC were measured with a transverse scan of the fetal head to establish normative values. Following establishment of CPC/VC ratios for normocephalic fetuses, an additional eight fetuses with suspected ventriculomegaly at the time of routine ultrasound were scanned.

RESULTS

Of the 185 fetuses for normal pregnancies who met the criteria for this study, all were normocephalic at birth. Of the eight fetuses who were suspected to have ventriculomegaly on ultrasound, all were diagnosed as moderately to severely hydrocephalic on autopsy after second-trimester termination.

CONCLUSION

The CPC/VC ratio is able to unequivocally distinguish between the overtly hydrocephalic and normocephalic fetus. The results of this study suggest that CPC and VC measurements may be valuable when hydrocephalus is suspected and there are equivocal ventricular/hemispheric width measurements.