INCLINED VERTEX PRESENTATIONS.
the obliquity of Naegele and Dubois, at least at the level of the superior strait, we hold that the head enters the pelvic inlet perpendicularly, i.e., with the sagittal suture in the axis of this strait. Now, it is not always so, and cases occur in which this suture looks toward the front or the back of the pelvis. In other cases, as a result of failure o: in exaggeration of flexion, the forehead or the occiput present at about the centre of the pelvis (Vorderscheitelstellung-Hinterscheitelstellung of the Germans). These cases are called inclined or irregular vertex presen tations. These irregularities are not important, for, under the influence of the unaided uterine efforts, the inclination corrects itself, the presen tation becomes one of the face or of the vertex, and labor is spontaneously completed, as if the head had originally been in the normal position. This is not always true, and the exaggerated inclination of the head may become a real cause of dystocia.
The prognosis of vertex presentations is subject to some uncertainties, but, in a general way, these presentations are the most favorable of all. Aside from the cases in which, rotation failing, the obstetrician is obliged to interfere, labor is much protracted when the occiput rotates backward. The fcetus, in these cases, corresponds to a rigid stem, which
must traverse a crooked canal, and, as we will see, the danger for both mother and child increases with the prolongation of labor. Even when rota tion occurs, the conditions are less favorable. The head remains elevated, the dilatation of the cervix is less easily accomplished, the membranes rupture earlier, the efforts, and consequently the exhaustion, of the woman are more severe in the first stage. Moreover, since the occiput has to make a longer journey, it is necessary that the pains be more energetic, and it is not rare to see a uterus, exhausted by producing rotation, and thus unable to overcome the perinea] resistance, become atonic. In this case obstetrical intervention is requisite to produce expulsion of the head. It is, besides, especially in the posterior positions, that the caput suc cedaneum, surpassing the limits of the sc,alp,, involves the bones and even the encephalon. (This happens most frequently in contracted pelvis). In occiput posterior labors the perineum is greatly endangered, and it is especially in these cases that complete or central perinea] lacerations occur. The treatment will be considered after the subject of labor.