Ductus Arteriosus, PatentLigationInfant, Premature, DiseasesInfant, PrematureIndomethacinEmbolization, TherapeuticInfant, NewbornDelayed DiagnosisPrenatal DiagnosisEarly DiagnosisSensitivity and SpecificityDiagnosisRetrospective StudiesDiagnostic ErrorsTime FactorsTomography, X-Ray ComputedBiopsyNursing DiagnosisDiagnosis, Computer-AssistedPredictive Value of TestsTreatment OutcomeReproducibility of ResultsDNA LigasesPolymerase Chain ReactionProspective Studies