Pelvimetry by Three-Dimensional Computed Tomography in Non-Pregnant Multiparous Women Who Delivered Vaginally

We assessed retrospectively the reference values of pelvic dimensions by 3D CT performed for non-obstetrical indications in non-pregnant multiparous women with a successful vaginal delivery. We further aimed to evaluate the impact of maternal short stature on these parameters.

The 3D CT pelvimetry was performed retrospectively in 203 non-pregnant women selected consecutively if they had at least one singleton term delivery with head presentation and if there was no history of maternal or fetal birth trauma or cerebral palsy after childbirth. With standard sagittal and reformatted axial-oblique views, anteroposterior including three conjugates of pelvic inlet, transverse, posterior sagittal diameters of pelvic inlet, the plane of greatest diameter, the plane of least diameter, and pelvic outlet were measured. Selected obstetric parameters were collected.

Overall, the pelvises had transverse oval appearance in inlet and size of the female pelvis. The diagonal conjugate was at least 15 mm longer than the obstetric conjugate. Women with short stature had lower maximal birth weight, and this was in accordance with their somewhat lower pelvic diameters.

The findings of this study present the reference values of the main planes of the true pelvis by 3D CT pelvimetry in a relatively large group of multiparous women who passed a trial of labor successfully. Overall, the pelvises had features of female pelvic bony structure although pelvic diameters were somewhat lower in multiparous women with short stature. The 3D pelvimetry with CT applications may be used as an adjunct to clinical and ultrasonographic examinations to rule out cephalopelvic dystocia in selected cases.