2. This torsion is not greater at the first than in the last cervical verte 3. At no point is there deformity or flattening of the rachidian canal.
4. The spinal marrow is at the centre of this canal. It is, therefore, not compressed, but is turned on its axis, parallel to that of the verte bra.
Bailly has very exactly described the mancenvre: " The diagnosis of the position having been made with the greatest care, the forceps is applied as usual. The head is grasped by its sides, the concavity of the border of the blades being turned towards the fronto-bregmatic region. If the bead be already near the vulva, we may at once begin to rotate. If, how ever, it be still above the inferior strait, it is brought down to the pelvic floor until this musculo-membranous plane is considerably distended. This lowering of the head is to me of the greatest importance. On the one hand, we thus conform more nearly to the natural process, when, in general, the head does not rotate till it reaches the pelvic floor; and, on the other hand, artificial rotation is easier, and freer from danger to the mother, since the head and the instrument are turned in but one axis, and where the surroundings are largely soft and mobile, instead of being turned at the centre of a curved and a rigid canal. (Fig. 98.) The head, then, having been lowered, and the perineum partially dis tended, movements of rotation are applied to it, to bring the occiput under the pubes. To accomplish this, the handles of the forceps are care fully and slowly turned towards the side of the pelvis opposed to which the occiput must follow, and this latter must be conducted along the line it would naturally pursue, that is to say, forwards and to the right in the left postero-lateral position, forwards and to the left in the occipito-iliac right posterior position. This manoeuvre never requires effort on the part of the accoucheur, but only, at the start, moderate im pulsion. As soon as the occiput has crossed the transverse diameter of the genital tract, especially if uterine contractions are present, rotation takes place alone and quickly, and the occiput is in front, and the concave border of the forceps against the fourchette.
Notwithstanding this reversal of the normal position of the forceps, the head may still be extended and delivered. A new and regular applica tion of the instrument seems to me, therefore, superfluous in the great majority of cases. In many cases, indeed, both the head and the instru ment are expelled together by a uterine contraction, as soon as rotation has been completed.
It is surprising, indeed, with what ease this rotation is made. With Bailly we believe it useless, ordinarily, to remove and re apply the for ceps, at least in multiparre; but in primiparle, with narrow vulva, it is frequently of great advantage to remove the forceps, and re-apply it to the head with occiput under the pubes.
[The absolute lack of reference to the practice of American accou cheurs in the delivery of occiput posterior positions, is valid excuse for reference to the matter hero. It is generally agreed that the main factor interfering with anterior rotation, in a normal pelvis, is lack of flexion of the head. When flexion is complete, in the large proportion of eases, as
soon as the occiput reaches the pelvic floor, other conditions normal, it will rotate spontaneously forward. Where flexion is not complete, we are satisfied that application of the forceps in the reverse direction and completion by them of flexion, will often be sufficient to cause the head to rotate spontaneously. If this be the case, an effort in this direction should ever be made before attempting artificial rotation by either the hand or the forceps. Lusk says that " an attempt to rotate the occiput around to the symphysis by instrumental means, is rarely successful." In a discussion in 1881 before the American Gynecological Society, Saw yer stated that he was opposed to dragging the head posterior by means of the forceps, and counsels rotation under an antesthetic by means of the entire hand in the vagina. This, to us, seems far preferable to the arti ficial rotation by the forceps, since the hand is a sentient agent. Richard son stated that, in a large experience, he had never failed to see the occi put rotate spontaneously. Reamy nearly agreed with him; the late Albert H. Smith said that in his experience, with a normal head and a normal pelvis, rotation always occurred. In a number of cases seen by us, in certainly the majority, spontaneous rotation occurred as soon as the head reached the floor of the pelvis; in one case lack of rotation was due to lack of flexion, and, on correcting this with the forceps applied inversely, spontaneous rotation immediately occurred. In three or four cases, the position was persistent, and the head and shoulders so firmly pressed down, that any attempt at artificial rotation could only have resulted in failure, and in possible injury, so that we delivered with the forceps, sav ing the children, but of course ploughing up the perineum.—Ed.] 3. Position 0.I.L.A.—The occipito-frontal diameter lies in the left oblique of the pelvis, the bi-parietal in the right oblique. The left side of the head is backward and to the left; the right forward and to the right. The forceps, then, applied symmetrically to the head, will be oblique to the pelvis. One blade being in front, and the other behind, the application is oblique. The posterior, first applied, is the left blade, and lies in front of the left sacro-iliac synchondrosis on the left lateral side of the head. The right blade, at first directed backward, in front of the sciatic ligament, should be brought forward behind the cotyloid cav ity, on the right side of the head, after Mme. Lachapelle's method. The forceps, when locked, will seize the occiput by its lesser curve directed towards the left thigh of the mother. (Fig. 99.) The first tractions should aim at bringing the head down to the pelvic floor, and then it is to be rotated from left to right, to bring the occiput under the pubes. This once accomplished, the instrument is symmetrical to head and to pelvis, and extraction is proceeded with as in case of occipito-pubic posi tions.