title: Dilated fourth ventricle in fetuses with trisomy 18, trisomy 13 and triploidy at 11-13 weeks' gestation.
abstract: OBJECTIVE
  To determine if in fetuses with aneuploidies the diameter of the fourth cerebral ventricle at 11-13 weeks' gestation is different from euploid fetuses.
  
  
  METHODS
  The fourth ventricle at 11-13 weeks' gestation was assessed in 62 cases of trisomy 21, 32 of trisomy 18, 10 of trisomy 13, and 12 of triploidy and compared to 410 normal euploid fetuses. Transvaginal sonography was carried out and 3D brain volumes were acquired. The fetal head was assessed in an axial plane and the diameter of the fourth ventricle was measured. Values in aneuploid and euploid fetuses were compared.
  
  
  RESULTS
  The diameter of the fourth ventricle in trisomy 18, trisomy 13 and triploidy, but not in trisomy 21, was significantly higher than in euploid fetuses. In the euploid fetuses the median diameter of the fourth ventricle was 1.9 mm and the 95th percentile was 2.5 mm. The measurements were above the median and the 95th percentile in 25 (78.1%) and 17 (53.1%) cases of trisomy 18, in 10 (100%) and 8 (80.0%) of trisomy 13, and in 10 (83.3%) and 10 (83.3%) of triploidy.
  
  
  CONCLUSIONS
  In trisomy 18, trisomy 13 and triploidy the diameter of the fourth ventricle at 11-13 weeks' gestation is increased.
authors: Department of Obstetrics and Gynecology, S. João Hospital, Medical School, University of Porto, Porto, Portugal.
authors: Teresa
authors: T
authors: Loureiro
authors: Ana Fatima A
authors: AF
authors: Ferreira
authors: Fred
authors: F
authors: Ushakov
authors: Nuno
authors: N
authors: Montenegro
authors: Kypros H
authors: KH
authors: Nicolaides
mesh_terms: D000328:Adult; D025063:Chromosome Disorders / Q000000981:diagnostic imaging / Q000196:embryology / Q000473:pathology*; D002882:Chromosomes, Human, Pair 13 / Q000000981:diagnostic imaging; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics; D018568:Crown-Rump Length; D004108:Dilatation, Pathologic / Q000000981:diagnostic imaging / Q000196:embryology; D004314:Down Syndrome / Q000000981:diagnostic imaging / Q000196:embryology / Q000473:pathology; D005260:Female; D020546:Fourth Ventricle / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000196:embryology; D005865:Gestational Age; D006785:Hospitals, University; D006801:Humans; D021621:Imaging, Three-Dimensional; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D057885:Triploidy; D014314:Trisomy / Q000473:pathology*; D000073839:Trisomy 13 Syndrome; D016216:Ultrasonography, Prenatal; D055815:Young Adult