OP13.03: Prenatal findings and outcome of open and closed spina bifida: analysis of 164 cases

Abstract

(FAPD/BPD, FLLD/BPD) and the perimeter and area for the HC (FPer/HC, FA/HC). The best curve to fit the relationships of the different variables with gestational age was identified and the changes in the absolute fontanelle size and of its relationship with the fetal head during gestation were analyzed. Results: A linear regression model fitted FLLD, FA, and all ratios, while a quadratic regression model fitted FAPD and FPer. The absolute size of the fontanelle significantly increased during the first half of pregnancy, until 26 weeks of gestation, to plateau or decrease thereafter. However, all ratios showed a significant negative correlation with advancing gestational age. Conclusions: This study suggests that the rapid growth of the fetal head, determined by the expansion of the brain, occurs faster than the ossification of the cranial bones and the anterior fontanelle. This determines an increase in the absolute size of the fontanelle despite the fact that its size relative to the whole volume of the fetal head is rapidly decreasing. It could be suggested that it is the fetal head that grows around the anterior fontanelle rather than the latter reducing in size during gestation. These data may be of help in understanding the mechanism behind an abnormal fontanelle development (delayed ossification or premature closure).