Various standardized measurements are used to follow ventricular size in infants with ultrasonography. These measurements are applied in the coronal and sagittal planes. Many studies provide reference ranges of such parameters on ultrasound in an attempt to distinguish normal from abnormal and to help clinicians improve diagnostic and therapeutic evaluation. Ratios [e.g., frontal horn ratio (FHR)] are considered to be less useful for monitoring ventricular size compared to the ventricular index. Interpretation of ventricular measurements should combine multiple lines of clinical evidence because in very premature infants considerable variation and asymmetry exist between the lateral ventricles, and variation in operator interpretation always occurs (8, 15, 47, 52, 78, 79, 88).