Fetal proximal humeral epiphysis as an indicator of term gestation in different ethnic groups.

OBJECTIVES: Accurate pregnancy dating is critical for appropriate clinical management. Our aim was to determine the time of appearance of proximal humeral epiphysis (PHE), consistency of its appearance among ethnic groups and whether 3D imaging helps with its visualization. METHODS: A cross-sectional study was done on 360 patients with 563 scans in different ethnic groups between August 2013 and July 2015. Inclusion criteria were singleton pregnancies (34-40+ weeks of gestation), well dated by <20 weeks sonogram. RESULTS: PHE was not seen at 34 (n = 44) or 35 weeks (n = 36) and was present at gestational ages 36 (n = 3), 37 (n = 126), 38 (n = 96), 39 (n = 100) and 40 weeks (n = 28) in 2%, 12%, 51%, 75% and 100%, respectively. PHE was seen in 20 of 50 (60%) African-Americans, 22 of 61 (64%) south Asians, 41 of 72 (57%) Caucasians, 45 of 86 (48%) Hispanics and 41 of 80 (49%) Asians. CONCLUSION: Appearance of PHE did increase with gestational age, prior to 40 weeks, it was not uniformly present and was seen as early as 36 weeks independent of ethnic group.