Abstract
X-ray pictures of the pelvic inlet were taken following the methods of Martiu and Guthmann. Measurements on the films thus taken were converted into actual measurements by proportional calculation to obtain mean measurements and their deviations of varying conjugations. Shapes of the pelvic inlet were classified into 5 groups of 14 types for the stochastic obseruation of the morphological and clinical findings. Results obtained were as follows.
1. Regarding the shapes of pelvic inlet, frequency of the appearance of gvnecoid type was 73.3% platypelloid-gynecoid type 12.2%, gynecoid-android type 3.6%, platvpelloid type 3.3%, android-gynecoid type 1.3%, platypelloid-anthropoid type 1.0%, anthropoid type 0.7%, anthropoid-gynecoid type 0.7%, and platypelloid-android type 0.3%.
2. Gynecoid and anthropoid types showed low pelvic index. All cases of platypelloid type showed high index in the front but 25.5% of them showed low index in the rear portion. While, android type showed low index in the front but high index in the rear portion.
3. When the space available for the fetal cranium in the plane of the pelvic inlet was expressed in the term of the maximum circumference, the most favorable type was gynecoid. Platypelloid type was narrow in the vertical conjugate, android type was defficient in the vertical conjugate in the rear and also in the horizontal conjugate of the front, and anthropoid type was insufficient in the horizontal conjugate.
4. Platypelloid and android types, in the plane of the pelvic inlet, have no association with the platypelloid sacrum. Side curve of the first sacral vertebra does not run in parallel with the vertical curve of the sacrum. There was no practical difference, moreover, in the frequency of the appearance of tubiform pelvis and funnel pelvis by the difference of the shape of pelvic inlet. Of funnel pelvis, however, those with platypelloid or anthropoid type in the rear portion of the pelvic inlet were strongly funnel shaped in many cases.
5. Mean of the vertical conjugate was from the 12.39cm of anthropoid-gynecoid type to the 9.21cm of the android-gynecoid type. Mean of the horizontal conjugate was from thel2.92cm of platypelloid-android type to the 10.18cm of anthropoid type.
6. Those flat in the rear portion of the pelvic inlet showed higher incidence rate of cesarean section and generally required longer period of labor.
7. Those with pelvic conjugate less than 10.5cm were found to show higher incidence rate of cesarean section.
