Background Cranial ultrasonography (US) is an established modality for detection of brain injury in very low birth weight infants. Intraventricular hemorrhage (IVH) and periventricular leukomalacia (PVL) are major brain abnormalities detected on US that could affect neurological development of preterm infants. In infants less than 1500 g birth weight and/or less than 33 weeks gestation, 12-51% have abnormal findings on US. At our institution, it has been our practice to obtain a sonogram at 7-10 days of age for infants 33 weeks gestation or less and/or birth weight less than 1600 g. A repeat sonogram is obtained at 40 weeks postconceptional age for infants 30 weeks gestation or less and/or birth weight less than 1250 g.
Objective To describe the prevalence of abnormal sonograms among infants from 30-33 weeks gestation.
Methods Records of infants 30-33 weeks born January 1, 1999 to June 30, 2004, were reviewed and data were collected.
Results 486 infants of 30-33 weeks gestation had screening cranial US performed. IVH occurred in 22 of 486 (4.5%). Of the 22 infants, 4 infants had significant IVH (grade III and/or grade IV). Of the 4 infants with significant IVH, 2 were 30 weeks and 2 were 31 weeks gestation. All 4 infants had either significant risk factors for brain injury (abruption, asphyxia) or clinical symptoms (seizures) that would warrant US during their hospital course. Of the 486 infants who had US, 5 additional infants (1%) had PVL, and 2 of these 5 had risk factors (abruption, shock) that warranted obtaining a sonogram. There was a statistically significant trend towards fewer abnormal sonograms from 33 weeks to 30 weeks gestation (p = .04). (table)
Conclusion There is an extremely small percentage of premature infants older than 30 weeks gestation in whom US findings would alter treatment or provide prognostic information. Our data support that cranial sonograms are not routinely recommended in neonates over 30 weeks gestation unless there are risk factors or clinical symptoms indicating a possible brain lesion.