[Obstetric pelvimetry using nuclear magnetic resonance tomography (MRI): clinical experiences with 150 patients].

Between Oct. 1987 and Oct. 1991 150 patients of the Frauenklinik Freiburg were examined by MR pelvimetry (MRI), 135 of which were "ante partum", i.e. just before delivery. The indications were: earlier operative or strongly protracted delivery, clinical suspicion of disproportion between head and pelvis, or obstetrical "problem pelvis" indicated by manual pelvic examination or ultrasonic foetometry. Previous experimental measurements with a phantom and the comparison with conventional radiograms by Guthmann and Martius of 10 patients in puerperium have shown, that the mean divergence was +/- 2 mm, the maximum divergence 5 mm. The MRI method for pelvimetry "ante partum" or in childbed, proved to be a method of high accuracy and a very good option to judge the pelvic shape, whilst being well accepted by the patients. Furthermore, it allows to determine the foetal BIP (biparietal head-diameter), to judge the pelvic soft-tissue, as well as the visualisation of the birth canal, all without any exposure to radiation. MR pelvimetry is thus part of today's clinical routine. The disadvantages are still the high costs as well as the fact, that only few centres have access to MRI equipment. Nevertheless, the pelvimetry "post partum" can be safely practised radiologically due to the very low radiation exposure.