Bi-iliac distance and iliac bone position compared to the vertebral columnin normal fetal development

Prenatal standards of bi-iliac width were not found in the literature based on autopsy investigations, nor was the caudo-cranial position of the ilia compared to the vertebral column. The first purpose of the present study wa s to establish normal standard values for the bi-iliac distance in fetal li fe, the second to evaluate the level of the iliac bones proportional to the ossified vertebral column. Whole body radiographs in anteroposterior proje ctions from 98 human fetuses (36 female and 44 male fetuses, as well as 18 fetuses on which the sex had not been determined) were analyzed in the stud y, The fetuses derived from spontaneous or induced abortions and they were radiographed as part of the required autopsy procedure. The crown-rump-leng th (CRL) of the fetuses varied from 32 to 245mm, The outer and inner bi-ili ac distance was measured from the radiographs with a digital Helios slide c aliper. The caudo-cranial position of the iliac bones was evaluated, The pr esent study shows that in normal fetal development there is a continuous li near enlargement of the pelvic region in the transverse and vertical planes , The upper iliac contour stays at the level of the first sacral vertebral body, whereas the lower iliac line moves caudally, Significant differences between male and female fetuses were not found. The value of the present st udy is that the results can be used as reference standards in prenatal path ology. (C) 2001 Wiley-Liss, Inc.