title: Corpus luteum across the first trimester: size and laterality as observed by ultrasound.
abstract: OBJECTIVE
  To study the site and size of the corpus luteum (CL) across the first trimester of pregnancy.
  
  
  METHODS
  Retrospective observational study of 1,806 ultrasound scans performed at 5 to 9 (+6 d) weeks' gestation, as well as a prospective study (n = 313) performed at 10 to 13 (+6 d) weeks' gestation.
  
  
  METHODS
  Four ultrasound practices across Victoria, Australia.
  
  
  METHODS
  Two thousand one hundred nineteen pregnant women.
  
  
  METHODS
  Transvaginal ultrasound.
  
  
  METHODS
  Side and size (diameter) of the CL.
  
  
  RESULTS
  At 5 to 9 weeks' gestation, the mean CL diameter was 19.3 mm, with no statistically significant variation across each gestational week. Corpus luteum size then statistically significantly declined at 10 to 13 weeks' gestation, with a mean diameter of 16.85 mm. Of 237 women in whom both ovaries were visualized at 10 to 13 weeks' gestation, a CL was seen in 82% of cases. A statistically significant right-sided bias was observed in both groups (54% at 5-9 wk gestation, 56% at 10-13 wk).
  
  
  CONCLUSIONS
  The CL remains static in size across 5 to 9 weeks' gestation, then its size declines or it disappears from 10 to 13 weeks. A novel right-sided ovulation bias occurs in human beings.
authors.affiliation: Monash Ultrasound for Women, Monash IVF, Epworth Hospital, Richmond, Australia.
authors.forename: Katrina
authors.initials: K
authors.lastname: Rowan
authors.forename: Simon
authors.initials: S
authors.lastname: Meagher
authors.forename: Mark
authors.initials: M
authors.lastname: Teoh
authors.forename: Beverley
authors.initials: B
authors.lastname: Vollenhoven
authors.forename: Shawn
authors.initials: S
authors.lastname: Choong
authors.forename: Stephen
authors.initials: S
authors.lastname: Tong
mesh_terms: D003338:Corpus Luteum / Q000000981:diagnostic imaging*; D005260:Female; D007839:Functional Laterality; D005865:Gestational Age; D006801:Humans; D010060:Ovulation; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D012189:Retrospective Studies; D018615:Ultrasonography, Doppler, Color; D016216:Ultrasonography, Prenatal; D014739:Victoria