Background Cerebellar growth in late gestation is impeded by prematurity which may adversely affect neurocognitive development. Assessment of cerebellar growth should be easily attainable, reliable and reproducible.

Objective To assess the reliability of linear sonographic cerebellar vermis measurement.

Method Cranial ultrasounds of 110 infants ranging from 24 to 41 weeks' gestation were retrospectively reviewed. Cerebellar vermian height, craniocaudal diameter and superior and inferior vermis widths were independently measured on the first midline sagittal image by three neonatal sonologists of varying experience. Interobserver and intraobserver reliability were calculated using the intraclass correlation coefficient (ICC) (2 way mixed model, SPSS V.15.0).

Results 61 images were technically adequate. Interobserver ICCs (95% CI) were: cerebellar vermian height 0.88 (0.82 to 0.92); craniocaudal diameter 0.91 (0.86 to 0.94); superior vermis width 0.84 (0.77 to 0.89); inferior vermis width 0.92 (0.89 to 0.95). Intraobserver ICCs were similar.

Conclusion With adequate images, linear ultrasound measurements of cerebellar vermis are reliable.