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Bi-iliac distance and iliac bone position compared to the vertebral column in normal fetal development
U B Hartling1, B Fischer Hansen, L T Skovgaard
1Department of Pathology, Hvidovre University Hospital, Copenhagen, Denmark.
Insights
This study establishes normal bi-iliac width and iliac bone position standards for fetal development using radiographs. These findings provide crucial prenatal reference values for pathology assessments.
Area of Science:
- Anatomy
- Radiology
- Prenatal Medicine
Background:
- Bi-iliac width standards in fetal life are lacking in current literature.
- The relationship between iliac bone position and the vertebral column during fetal development is not well-documented.
Purpose of the Study:
- To establish normal standard values for bi-iliac distance in fetal life.
- To evaluate the caudo-cranial position of the iliac bones relative to the ossified vertebral column.
- To provide reference standards for prenatal pathology.
Main Methods:
- Analysis of whole-body antero-posterior radiographs from 98 human fetuses (CRL 32-245 mm).
- Measurement of outer and inner bi-iliac distances using digital calipers.
- Evaluation of the caudo-cranial position of the iliac bones relative to the sacrum.
Main Results:
- Demonstrated continuous linear enlargement of the pelvic region in transverse and vertical planes during normal fetal development.
- Identified the upper iliac contour at the level of the first sacral vertebral body.
- Observed the lower iliac line moving caudally without significant sex-based differences.
Conclusions:
- Established normative standards for fetal bi-iliac width and iliac bone positioning.
- Results indicate consistent anatomical development of the fetal pelvis.
- Findings offer valuable reference data for diagnosing and managing prenatal pathologies.
Abstract:
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 was to establish normal standard values for the bi-iliac distance in fetal life, the second to evaluate the level of the iliac bones proportional to the ossified vertebral column. Whole body radiographs in antero-posterior projections 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 study. The fetuses derived from spontaneous or induced abortions and they were radiographed as part of the required autopsy procedure. The crown-rump-length (CRL) of the fetuses varied from 32 to 245 mm. The outer and inner bi-iliac distance was measured from the radiographs with a digital Helios slide caliper. The caudo-cranial position of the iliac bones was evaluated. The present study shows that in normal fetal development there is a continuous linear 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 study is that the results can be used as reference standards in prenatal pathology.