title: Comparison of conventional versus three-dimensional ultrasound in fetal renal pelvis measurement and their potential prediction of neonatal uropathies.
abstract: OBJECTIVE
  To establish a threshold value for fetal renal pelvis dilatation measured by automatic volume calculation (SonoAVC) in the third trimester of pregnancy to predict neonatal uropathies, and to compare these results with conventional antero-posterior (AP) measurement, fetal kidney 3D volume and renal parenchymal thickness.
  
  
  METHODS
  In a prospective cohort study, 125 fetuses with renal pelvis AP diameter of ≥5 mm both at 20 weeks of gestation and in the third trimester, underwent an additional 3D volume measurement of the fetal kidney in the third trimester. Receiver operating characteristic (ROC) curves for establishing threshold values for fetal renal pelvis volume, AP measurement, fetal kidney volume and renal parenchymal thickness to predict neonatal uropathies were analyzed. Also, sensitivity, specificity, area under the curve (AUC) and likelihood ratios were calculated.
  
  
  RESULTS
  A cut-off point of 1.58 cm³ was identified in the third trimester of pregnancy (AUC 0.865 (95% CI 0.789-0.940), sensitivity 76.3%, specificity 87.4%, LR+ 6.06, LR- 0.27) for measurements with SonoAVC. A cut-off value of 11.5 mm was established in the third trimester of pregnancy (AUC 0.828 (95% CI 0.737-0.918), sensitivity 71.1%, specificity 85.1%, LR+ 4.77, LR- 0.34) for the conventional AP measurement. A cut-off point for fetal kidney volume was calculated at 13.29 cm³ (AUC 0.769 (95% CI 0.657-0.881), sensitivity 71%, specificity 66%, LR+ 2.09, LR- 0.44). For renal parenchymal thickness, a cut-off point of 8.4 mm was established (AUC 0.216 (95% CI 0.117-0.315), sensitivity 31.6%, specificity 32.6%, LR+ 0.47, LR- 2.10).
  
  
  CONCLUSIONS
  This study demonstrates that 3D fetal renal pelvis volume measurements and AP measurements both have a good and comparable diagnostic performance, fetal renal volume a fair accuracy and renal parenchymal thickness a poor accuracy in predicting postnatal renal outcome.
authors.affiliation: a Department of Obstetrics and Gynecology , University Medical Center , Groningen , the Netherlands and.
authors.forename: L K
authors.initials: LK
authors.lastname: Duin
authors.affiliation: b Department of Obstetrics and Gynecology , Maastricht University Medical Center , Maastricht , the Netherlands.
authors.forename: J G
authors.initials: JG
authors.lastname: Nijhuis
authors.affiliation: a Department of Obstetrics and Gynecology , University Medical Center , Groningen , the Netherlands and.
authors.forename: S A
authors.initials: SA
authors.lastname: Scherjon
authors.affiliation: b Department of Obstetrics and Gynecology , Maastricht University Medical Center , Maastricht , the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Vossen
authors.affiliation: b Department of Obstetrics and Gynecology , Maastricht University Medical Center , Maastricht , the Netherlands.
authors.forename: C
authors.initials: C
authors.lastname: Willekes
mesh_terms: D019540:Area Under Curve; D015331:Cohort Studies; D005260:Female; D005333:Fetus; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000000981:diagnostic imaging; D007668:Kidney; D007682:Kidney Pelvis / Q000000981:diagnostic imaging*; D008297:Male; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D058536:Pyelectasis / Q000000981:diagnostic imaging*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014570:Urologic Diseases / Q000000981:diagnostic imaging*
keywords: Fetal renal pelvis; SonoAVC; hydronephrosis; pyelectasis