Acceleration and plateau: two patterns and outcomes of isolated severe fetal cerebral ventricular dilation.

Objectives: We sought to characterize patterns of in utero dilation in isolated severe fetal ventriculomegaly (ISVM) and investigate their value in predicting obstetrical and postnatal outcomes.
Methods: This is a retrospective cohort study. ISVM was defined as a sonographic cerebral ventricle atrial with width ≥15 mm in the absence of additional cerebral or other anatomic anomalies. The aim of this study was to characterize two ISVM groups using a receiver operator curve to evaluate the rate of ventricular progression versus need for ventriculoperitoneal (VP) shunt postnatally. Outcomes were compared between the groups using Pearson's chi-squared test, Student t -test, and descriptive statistics.
Results: Based on the ROC analysis, ventricular growth of ≥3 mm/week versus <3 mm/week distinguished fetuses likely to require a postnatal VP shunt. Fetuses were characterized as accelerators if ventricle growth was ≥3 mm/week at any point and plateaus if <3 mm/week. Accelerators showed a greater average rate of ventricle progression than plateaus (4.1 vs. 1.0 mm/week, respectively, p  = .031) and were more likely to be delivered at earlier gestational ages (34.7 vs. 37.1 weeks respectively, p  = .02). Ninety percent of accelerators demonstrated a need for shunt placement compared with 18.8% of plateaus ( p  < .001). Significantly more plateaus (87.5%) underwent a trial of labor while accelerators were more likely to have planned cesareans (70%, p  = .009).
Conclusions: This study characterizes ISVM into two distinct populations based upon the rate of ventricle expansion, differentiated by the need for postnatal shunting. Once a ventricular growth pattern is determined, these distinctions should prove useful in prenatal management and delivery planning.