title: Intracranial translucency at 11-13 weeks of gestation: prospective evaluation and reproducibility of measurements.
abstract: OBJECTIVE
  This paper aimed to determine the feasibility of identification and measurement reproducibility of intracranial translucency (IT) in our population.
  
  
  METHODS
  This is a prospective study in which five accredited operators attempted to identify and measure the IT during first-trimester sonographic screening for aneuploidy in 990 fetuses. The presence or absence of spina bifida was determined at the time of the second-trimester scan or after birth. Measurement reproducibility was assessed through intraclass correlation coefficient (ICC) on a subgroup of 150 fetuses.
  
  
  RESULTS
  Identification and measurement of the IT were possible in 961 (97%) cases. The mean IT anteroposterior diameter was 1.8 mm (SD ± 0.37; range 0.8-3.1), and the size increased linearly with advancing gestation (IT = 0.74 + 0.02 × crown-rump length; r(2) = 0.15, p < 0.0001). The only fetus with spina bifida in this series presented with absent IT. Intra-observer and inter-observer ICCs were 0.79 and 0.75, respectively (95% confidence intervals 0.72-0.84 and 0.67-0.81, respectively; both p < 0.001).
  
  
  CONCLUSIONS
  The IT increases linearly with increasing crown-rump length and seems to be of value in the first-trimester detection of spina bifida. It is easy to identify and measure and shows excellent intra-observer and inter-observer reproducibility measurements.
authors.affiliation: Delta Ultrasound Center in Obstetrics and Gynecology, Madrid, Spain.
authors.forename: Begoña
authors.initials: B
authors.lastname: Adiego
authors.forename: Tamara
authors.initials: T
authors.lastname: Illescas
authors.forename: Pilar
authors.initials: P
authors.lastname: Martinez-Ten
authors.forename: Carmina
authors.initials: C
authors.lastname: Bermejo
authors.forename: Javier
authors.initials: J
authors.lastname: Perez-Pedregosa
authors.forename: Amy E
authors.initials: AE
authors.lastname: Wong
authors.forename: Waldo
authors.initials: W
authors.lastname: Sepulveda
mesh_terms: D000293:Adolescent; D000328:Adult; D018568:Crown-Rump Length; D004314:Down Syndrome / Q000000981:diagnostic imaging / Q000196:embryology; D004453:Echoencephalography / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D048208:Nuchal Translucency Measurement / Q000379:methods*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000502:physiology; D011262:Pregnancy Trimester, Second / Q000502:physiology; D015203:Reproducibility of Results; D016135:Spinal Dysraphism / Q000000981:diagnostic imaging / Q000196:embryology; D055815:Young Adult