title: Evaluation of fetal subarachnoid space using transabdominal ultrasonography and normal values during pregnancy.
abstract: OBJECTIVE
  To determine the feasibility of evaluating the subarachnoid space by measuring two novel sonographic parameters in axial section using transabdominal ultrasound, in addition to the parameters previously defined in coronal section, and to construct a normal range for the subarachnoid space width in singleton healthy fetuses.
  
  
  METHODS
  Healthy pregnant women between 20 and 29 weeks were scanned using transabdominal ultrasound. Four variables were measured for the evaluation of subarachnoid space width; sinocortical width and anterior craniocortical width in coronal plane, and lateral and posterior craniocortical width in axial plane.
  
  
  RESULTS
  The data of 154 patients were recorded. SCW could be measured in 87.6 % (135) of fetuses, while the same figure was 77.9 % (120), 96.1 % (151) and 98.1 % (148) for anterior, lateral and posterolateral CCW, respectively. The SCW and anterior CCW did not display a significant correlation with gestational age and head circumference. The mean of SCW was 1.55 ± 0.41 mm with a range of 0.85-3.87 mm. The mean anterior CCW was 1.63 ± 0.39 mm with a range of 0.85-2.82 mm. A linear regression line was plotted between gestational age and lateral CCW (r = 0.707; p < 0.0001) and posterolateral CCW (r = 0.437; p < 0.0001), and nomograms for these parameters are constructed.
  
  
  CONCLUSIONS
  This study presents a novel approach for the in utero evaluation of the subarachnoid space with two measurements in axial plane using transabdominal ultrasound. The nomograms will be helpful when there is a suspicion of subarachnoid space dilatation during routine cranial scan.
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Kanuni Sultan Suleyman Research and Teaching Hospital, Istanbul, Turkey.
authors.forename: Aytul
authors.initials: A
authors.lastname: Corbacioglu Esmer
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Istanbul University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Atil
authors.initials: A
authors.lastname: Yuksel
authors.affiliation: Division of Pediatric Neurology, Department of Pediatrics, Istanbul University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Tugce
authors.initials: T
authors.lastname: Aksu Uzunhan
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Istanbul University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Omer
authors.initials: O
authors.lastname: Demir
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Istanbul University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Tugba
authors.initials: T
authors.lastname: Sarac Sivrikoz
authors.affiliation: Division of Pediatric Neurology, Department of Pediatrics, Istanbul University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Nur
authors.initials: N
authors.lastname: Aydinli
keywords: Cranial scan; Nomogram; Prenatal diagnosis; Subarachnoid space; Ultrasound