ObjectiveTo explore the clinical value of ultrasonic features of intracranial structures in the diagnosis of open spina bifida(OSB) in fetus with 11 to 13⁺⁶ weeks of gestation.

MethodsEighty healthy fetuses and 80 fetuses with OSB at 11 to 13⁺⁶ weeks of gestation were divided into the health group and OSB group, respectively.The intracranial structures in two groups were detected using ultrasound.The intracranial transparency thickness(ITT), brain stem diameter(BS), brain stem-occipital distance(BSOB) were measured, and the ratio of BS/BSOB was calculated.

ResultsThe "8" shape of diencephalon to mesencephalon and ntracranial hyaline layer could be clearly displayed in health group.In OSB group, the diencephalon and mesencephalon distorted, the intracranial structures in the posterior fossa shifted, and the intracranial transparent layer partly blocked.The levels of ITT, BS and BSOB in OSB group were significantly lower than those in health group, and the BS/BSOB level in OSB group was significantly higher than that in health group(P < 0.01).In the term of OSB identification, the ITT less than 1.0 mm was set as the critical value, the results of ROC analysis showed that the sensitivity and specificity were 90.00% and 87.50%, respectively.The BS/BSOB more than 1.0 mm was set as the critical value, the sensitivity and specificity were 87.50% and 85.00%, respectively.When two indictors were considered together, the sensitivity and specificity were 97.5% and 97.5%, respectively.

ConclusionsThe morphological distortion of diencephalon and mesencephalon, reduction or disappearance of ITT, reduction of BS, BSOB and BS/BSOB increasing are the important ultrasonic features of intracranial structures of OSB.Observing the orphological characteristics of diencephalon and mesencephalon, and analyzing the ITT and BS/BSOB can help diagnose OSB, and the diagnosis effect is better under combining two aspects.It is worthy of further clinical promotion.