Along with appropriate testing for any identified problems or disorders, routine evaluations include pulse oximetry, complete blood count, electrolytes, bilirubin level, blood culture, serum calcium, alkaline phosphatase, and phosphorus levels (to screen for osteopenia of prematurity), hearing evaluation, cranial ultrasonography (to screen for intraventricular hemorrhage and periventricular leukomalacia), and screening by an ophthalmologist for retinopathy of prematurity.