title: Evaluation of placental volume at 7-10+6 weeks of pregnancy by 3D-sonography.
abstract: The aim of the study was to establish normative data for placental volume (PV) at 7-10+6 weeks of gestation using three-dimensional ultrasound (3DUS). The cross-sectional study involved 70 healthy pregnancies between 7 and 11 weeks. The VOCAL (Virtual Organ Computer-aided Analysis) method with a 30 degrees rotation angle and six planes was used for volumetric calculations. Regression models were constructed to assess the correlation between PV and crown-rump length (CRL) adjusted by the determination coefficient (R2). The method proposed by Royston and Wright was used to establish the 2.5th; 10th; 50th; 90th and 97.5th percentiles (percentile=mean+KxSD). The intraclass correlation coefficient (ICC), Bland-Altman graphs and Student's paired t-tests were used to assess intra- and interobserver variability. PV ranged from 1.7 to 42.6 cm3, with a mean of 13.6cm3 (+/-9.4cm3). There was a strong correlation between PV and CRL; the exponential equation was the model that best expressed the correlation between them (R2=0.76). For CRL between 9 and 40 mm, the mean PV increased 10.5 times, while CRL increased only 4.4 times. Inter- and intraobserver correlation were excellent (ICC=0.979 and 0.971, respectively). Bland-Altman graphs indicated a good reproducibility with a mean intraobserver and interobserver difference of 0.2 cm3 (95% CI: -0.7-1.2cm3) and -0.2cm3 (95% CI: -1.3-0.9cm3), respectively. Reference limits were generated for first trimester PV assessed by 3DUS using the VOCAL method. There is a strong correlation between PV and CRL. Placental volume obtained through this method was highly reproducible.
authors.affiliation: Department of Obstetrics, São Paulo Federal University (UNIFESP), Rua Carlos Weber, 950 Apto. 113 Visage, Alto da Lapa, São Paulo, SP, CEP 05303-000, Brazil.
authors.forename: L M M
authors.initials: LM
authors.lastname: Nardozza
authors.forename: P M
authors.initials: PM
authors.lastname: Nowak
authors.forename: E
authors.initials: E
authors.lastname: Araujo Júnior
authors.forename: H A
authors.initials: HA
authors.lastname: Guimarães Filho
authors.forename: L C
authors.initials: LC
authors.lastname: Rolo
authors.forename: M R
authors.initials: MR
authors.lastname: Torloni
authors.forename: A F
authors.initials: AF
authors.lastname: Moron
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D015588:Observer Variation; D010920:Placenta / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012016:Reference Values; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000592:standards* / Q000706:statistics & numerical data; D055815:Young Adult