title: Serial head ultrasound studies in preterm infants: how many normal studies does one infant need to exclude significant abnormalities?
abstract: OBJECTIVE
  We hypothesized that preterm infants with two normal head ultrasound (HUS) screening studies > or = 7 days apart would have subsequently normal follow-up studies.
  
  
  METHODS
  We reviewed reports of all HUS studies performed in preterm infants < or = 32 weeks gestation admitted to our nursery between January 1998 and July 2000.
  
  
  METHODS
  Regional perinatal referral center.
  
  
  METHODS
  A normal HUS screening study was defined as either no findings; or grade I intraventricular hemorrhage (IVH) (Papile classification), germinal matrix irregularity or cyst, or normal but unequal ventricular size. An abnormal study was defined as any with IVH > or = grade II, periventricular leukomalacia (PVL), ventriculomegaly (VM), or periventricular echogenicity (PVE).
  
  
  RESULTS
  Of 98 infants, 92 infants (94%) who had two normal HUS studies > or = 7 days apart had normal repeat studies subsequently, and six (6%) were abnormal. Four of the six abnormal infants were <25 weeks gestation at birth. One infant (27 weeks) became abnormal after culture-positive bacterial sepsis and necrotizing enterocolitis with bowel perforation requiring surgery. The remaining infant (29 weeks) had a question of PVE, and a normal repeat study. The positive predictive value for having a normal HUS after two previously normal studies > or = 7 days apart was 94% with a specificity of 86%.
  
  
  CONCLUSIONS
  Stable premature infants > or = 25 weeks gestation without intervening deterioration may not need repeat screening HUSs after having had two normal studies > or = 7 days apart. Unstable or extremely premature infants <25 weeks gestation may be subject to late severe IVH, VM, and PVL, and therefore need a repeat study before hospital discharge, even if two initial studies > or = 7 days apart were normal.
authors.affiliation: Division of Neonatology, Department of Pediatrics, University Hospital and Medical Center, State University of New York at Stony Brook, Stony, New York 11794-8111, USA.
authors.forename: Victoria N
authors.initials: VN
authors.lastname: Nwafor-Anene
authors.forename: Joseph D
authors.initials: JD
authors.lastname: DeCristofaro
authors.forename: Stephen
authors.initials: S
authors.lastname: Baumgart
mesh_terms: D002543:Cerebral Hemorrhage / Q000000981:diagnostic imaging; D002552:Cerebral Ventricles / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000000981:diagnostic imaging*; D007969:Leukomalacia, Periventricular / Q000000981:diagnostic imaging*; D008297:Male; D013997:Time Factors; D014463:Ultrasonography