Prevention of human birth trauma. IInd communication: Knowledge - Based birth planning and visualisation by means of imaging procedures and simulation aided by personal computer

To predict problems concerning birth anatomy data from maternal pelvic anat omy (involving soft tissue relations and the influence of dynamic effects s uch as deformations and movements of pelvic joints) are required as well as fetometric data, also with regard to dynamic factors such as head moulding during birth. Synoptic evaluation of these factors up to now was based on planimetric analysis taking into account primary data from pelvimetry by ma gnetic resonance imaging, ultrasonographic fetometry and maternal biometry. These data were validated by data bases deriving from correlative investig ations concerning complex maternal pelvic anatomy, pelvic soft tissue requi rements as well as biomechanical properties and tolerances of the structure s involved. The latter data had been obtained by birth simulations using fi nite element analysis under various anatomic conditions, involving high exp enditure for hard and software. Due to this visualisation of birth for the individual patient was not possible. Study Design: The system presented in this paper - ANAPELVIS 2.0- allows th ree-dimensional reconstruction of the individual birth channel based on the primary data and data bases mentioned above using a common Pentium-PC. Fet al head may be moved through this birth channel performing the typical move ments of flexion, deflexion and rotation, also taking into account moulding processes which are biomechanically tolerable. Fete-maternal disproportion s can be found and visualised in a three-dimensional manner. Up to now, the system has been used in 92 patients prone to fete-maternal disproportion a ccording to their obstetrical history or to general clinical features, such as external pelvic measurements. Results: The suspected disproportion was confirmed by the system in 54 case s. In no case was there a problem in the pelvic inlet; 4 midpelvis and 26 o utlet disproportions were found. These disproportioned types deriving from the plain planimetric assessment in the various pelvic planes were combined with a variety of more complex pathologies of pelvic anatomy (assimilation /canal pelvis, abnormal sacral flatness). In 23 cases these complex abnorma lities were responsible for the prediction of a disproportion alone, withou t pelvic contraction as assessed in the various pelvic planes. Conclusion: Although our previous system ANAPELVIS 1.0, which was essential ly based on the analysis of pelvic plane planimetry, revealed very acceptab le data for specificity (86%) and sensitivity (79%), the use of ANAPELVIS 2 .0 might enhance predictive correctness, as it optimises assessment of thes e complex pelvic pathologies. Furthermore, visualisation of the individual birth to be expected under given conditions is a helpful tool for the obste trician to inform the patient and for her to make decisions concerning birt h planning.