title: Early first-trimester trophoblast volume in pregnancies that result in live birth or miscarriage.
abstract: OBJECTIVE
  To assess the validity of trophoblast volume measurements on three-dimensional ultrasound (3D-US) with Virtual Organ Computer-aided AnaLysis (VOCAL(TM) ), to create reference values between 6 and 12 weeks of gestation and to compare trophoblast volume between pregnancies ending in miscarriage and those resulting in live birth.
  
  
  METHODS
  In a prospective periconceptional cohort, we performed weekly 3D-US in 112 singleton pregnancies resulting in a non-malformed live birth and in 56 ending in miscarriage. Scans were performed between 6 and 12 weeks. Trophoblast volumes were calculated by subtracting the gestational sac volume from the volume of the total pregnancy. The interobserver and intraobserver agreement of measurements were determined to assess validity. Reference values were created for trophoblast volume in relation to crown-rump length and gestational age.
  
  
  RESULTS
  A total of 722 3D-US examinations were available for offline VOCAL measurements, but measurements could be performed in only 53% of these due to non-targeted scanning and incomplete framing. Interobserver and intraobserver agreement for trophoblast volume measurements were excellent, with intraclass correlation coefficients > 0.97. Trophoblast volumes of pregnancies ending in miscarriage were significantly smaller (P < 0.01) than were those of pregnancies that resulted in live birth. Trophoblast growth in pregnancies ending in miscarriage was also reduced compared with that in pregnancies that resulted in live birth.
  
  
  CONCLUSIONS
  VOCAL is a valid technique for measuring trophoblast volume during the early first trimester of pregnancy. Pregnancies ending in miscarriage have smaller trophoblast volumes as well as reduced trophoblast growth compared with those that result in live birth.
authors.affiliation: Department of Obstetrics and Gynaecology, Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: A D
authors.initials: AD
authors.lastname: Reus
authors.forename: H
authors.initials: H
authors.lastname: El-Harbachi
authors.forename: M
authors.initials: M
authors.lastname: Rousian
authors.forename: S P
authors.initials: SP
authors.lastname: Willemsen
authors.forename: R P M
authors.initials: RP
authors.lastname: Steegers-Theunissen
authors.forename: E A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: N
authors.initials: N
authors.lastname: Exalto
mesh_terms: D000022:Abortion, Spontaneous / Q000473:pathology*; D000328:Adult; D018568:Crown-Rump Length; D005260:Female; D005865:Gestational Age; D058746:Gestational Sac / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D050498:Live Birth; D008875:Middle Aged; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D014327:Trophoblasts / Q000000981:diagnostic imaging*; D016216:Ultrasonography, Prenatal / Q000379:methods; D055815:Young Adult
keywords: VOCAL; early first trimester; miscarriage; placental volume; reproducibility; three-dimensional ultrasound; trophoblast volume