First-trimester ultrasound

Gestational age discrepancies due to acquisition artifact in the forensic fetal osteology collection at the National Museum of Natural History, Smithsonian Institution, USA

Previously, numerous techniques have been used to assess either lunar or gestational age from fetal remains, such as from the external dimensions of the fetus, presence or absence of external features and ossification centers. One of the largest fetal collections in the U.S. is assessed with regard to errors in its biologic profile (ancestry, sex and age), the nature of the collection process, the methods of collection and the subsequent considerations for usage. Hrdlicka recorded the age, ancestry, sex and external measurements on card catalogs in the early 1900s for future use. For the purpose of this pilot study, measurements on 38 suitable fetuses stored at NMNH were used to calculate lunar age and compare with the recorded age in the card catalog. The differences between the age assessments are as follows: 20 showed no difference, 11 were discrepant by one month, 6 varied by 2 months and 1 diverged by 5 months. The average difference between lunar ages is 0.74 months, reflecting a nearly three-week difference. The purpose of this paper is to demonstrate that such discrepancies exist and to confirm specimens with accurate ages, which can be marked for future research. Moreover, it is also the purpose of this paper to demonstrate that such bias artifact exists in museum collections, and that this artifact needs to be eliminated from the sample materials prior to study.