Fetal head biometry following in-utero repair of myelomeningocele

Objective To evaluate the impact of prenatal myelomeningocele repair on fetal bead biometry. Methods Fifty fetuses underwent open fetal myelomeningocele repair at our institution between January 1998 and July 2002. All bad serial bead circumference (HC) and lateral ventricular diameter (VD) measurements taken preoperatively and weekly for 8 weeks after repair. Cortical index (CI) was defined as HC/VD. Measurements were compared with gestational age-matched values from nomograms. One-sample t-test, ANOVA and repeated measures analysis were used to assess HC, VD and CI after fetal repair. Results Preoperatively, the HC in fetuses with myelomeningocele was smaller than control values (186.4 vs. 198.8 mm, P = 0.0004). Eight weeks' postoperatively this difference bad resolved (293 vs. 301.6 mm, P = 0.76). The mean increase in CI after repair was 20% (P = 0.02) compared with the predicted 51% in normal cases. The average increase in VD was 3.9 mm (38.8%, P < 0.001). Conclusions Mid-gestational repair of myelomeningocele alters fetal bead growth. Increased CI suggests HC changes are not due to ventriculomegaly alone. Copyright (C) 2004 ISUOG. Published by John Wiley & Sons, Ltd.