4. Position 0.I.L.T.--Here it is impossible to grasp the head in the bi-parietal diameter. One of the parietal protuberances corresponding directly with the posterior portion of the pelvis (sacro-vertebral angle), the other to the anterior portion, that is to say, to the symphysis, it is not possible to apply the forceps symmetrically to the head. In case we try, on the other hand, to apply symmetrically to the pelvis, we will grasp the head in the occipito-froutal diameter, the greatest of the head. We aim, hence, to grasp the head in the diameter intermediate between the bi-parietal and the occipito-frontal. The left blade is again first intro duced to the left and behind, on the left side of the occiput. The right blade, introduced the second, is first directed behind and to the right, and then brought spirally over the right frontal protuberance. The in strument, when locked, faces the left thigh of the mother. (Fig. 100.) The lesser curve is, therefore, again turned, although not exactly, towards the occiput. First, tractions are to be made downward, to bring the head to the pelvic floor, and it is then rotated from left to right, to bring the occiput under the pubes.
5. Position 0. L. occipito-frontal diameter lies in the right oblique of the pelvis. The occiput points to the left sacroiliac synchon drosis, the forehead to the right cotyloid cavity. The bi-parietal diame ter lies in the left oblique of the pelvis, the right side of the head is in front and to the left, the left side behind and to the right. Here again application is oblique.
The left blade necessarily occupying the left side of the pelvis, in order to be applied symmetrically to the head, must be placed at the extremity of the left oblique diameter, that is to say, in front and on the right side of the head. The right blade will be posterior, and should be inserted first, behind, on the left side of the head. Therefore, we will be obliged to cross the blades, unless we resort to Stoltz's method. The left blade, introduced the second, must be brought forward by the spiral movement of Mme. Lachapelle. If the head is well grasped, the lesser curve of the forceps will cross the forehead and be directed towards the right thigh of the mother.
The occiput being posterior, there are two methods of extraction: by Pajot's method, and extract the occiput posterior; or else, as we prefer, first pull the head down, and, once the head on the pelvic floor, rotate it from left to right, and from behind forward. The occiput under the pubes, the forceps will be applied inversely, and then, in multiparEe, we proceed to extract, or, in primiparEe, we remove the forceps and re apply it directly.
When the head is high up, the difficulty is sometimes great in bringing down the head. It is a good plan then to begin artificial rotation before
the head has quite reached the inferior strait.
6. Position The occipito-frontal diameter lies in the right of the pelvis; the right side of the head points backward and to the right, the left side forwards and to the left, the bi-parietal diameter being in the left oblique pelvic diameter. The forceps is applied symmetrically to the head, and oblique to the pelvis. The right blade, inserted first, is carried to the right side of the head, behind and to the right. The left blade is inserted second and to the left, and carried from behind forward, to the anterior extremity of the left oblique diameter of the pelvis, that is, on the left side of the head, in front and to the left, after Mme. La chapelle's method. When locked, the lesser curve crosses the occiput, and points to the right thigh of the mother. At first traction is made downward, and as soon as the head reaches the pelvic floor it is rotated from right to left to bring the occiput under the pubes. Since the right blade was inserted first, the blades must be crossed to lock, or else Stoltz's method used. The occiput under the pubes, the forceps is applied sym metrically to head and pelvis. Extraction is made as in the ordinary occipito-pubic position.
7. Position a I. R. T., The occipito-frontal diameter lies in the trans verse of the pelvis. The forehead is to the left, the occiput to the right, the diameter is in the of the pelvis, the right side of the head is posterior, the left anterior. The forceps cannot be applied symmetrically to the head. The same is true of the pelvis, since the head would be seized in its longest diameter, O.F. We seek, hence, as in 0.I.L.P., to grasp the head in a diameter between the and the occipito-frontal, and the head is seized irregularly. (Fig. 101.) The right blade, inserted first, is placed behind and to the right, over the right lateral 'portion of the occipital bone, at the level of the right eacro-iliac synchondrosis. The left blade, inserted second, behind and to the left, is brought forward by the spiral movement behind the left coty loid cavity, at the level of the left frontal protuberance. Here again, the blades must be crossed, or Stoltz's method used. The instrument once locked, has its lesser curve turned towards the right thigh of the woman, traction' s made downward to bring the head to the pelvic floor, then it is rotated from right to ]eft, and, the occiput once under the symphysis, we extract immediately in multiparEe, or else we remove the forceps in primiparle, and make a direct application.