We believe that it is always better, even when the head is at the infe rior strait, to introduce the entire hand, exclusive of the thumb, into the vagina. For it often happens, as Pinard has shown, that the foetal head is less freed from the cervix than is supposed. Often one of the cervical borders is in front of the head, and the other far up, and the cervix is more or less wounded when the blades are introduced.
We must never forget, further, that the use of the instrument requires long apprenticeship, and that in the beginning of practice, we cannot take too many precautions. The insertion of the entire hand gives perfect security to the accoucheur and his patient, and, by facilitating the intro duction of the blades, allows of more regular application without increas ing the suffering of the woman.
When the occiput is towards the pubes, or the sacrum, the guiding hand may be placed directly at the sides of the vulva; but when we are dealing with oblique presentations, it is better to place the hand flat at the posterior commissure, along the posterior vaginal wall. Here we find the most room, and the hand will penetrate the more readily, and then again we may depress the perineum with the back of the hand, which gives more space for manipulation.
6. The second Blade should always be inserted above the rule is to be taken in conjunction with the fourth. We have already seen that the posterior blade must first be introduced. Now this blade may, according to the case, be the right or the left. It results that when the left blade has been inserted first, locking is not at all difficult, since the pivot is beneath the right blade, which is inserted second and above, (Fig. 83), but when the right blade has been inserted first, the conditions are not the same. In this case the left blade being inserted second, that is, above the right blade, the lock-surface is on the opposite side to the pivot. In order to lock, therefore, it is necessary to pass the left blade beneath the right. This is called crossing the blades. To accomplish it, the extremities of the handles are gently held, without making any traction, and they are passed one above the other, so that the right blade will lie above the left. The difficulties and the dangers of this little manoeuvre have been much exaggerated. It succeeds usually without trouble. In order to avoid this crossing, Tureaux, Tarsitani, Th6nance, Valette, have modified the forceps. Stoltz goes further still, and does
away with crossing altogether. Seeing that the insertion of the right blade is usually more difficult than the left, whatever the position of the head, he first inserts the right blade, and then, to avoid crossing, he lifts this blade up, and introduces the second blade, the left, not above, but below the right. He then brings down the right, and the blades readily lock. We have used this method several times, and have succeeded with out trouble. This proves again that there is nothing absolute as to the choice of the first blade for introduction. Everything depends indeed on the peculiarities of the case. The main point is not to insist on inserting the one or the other blade first or second, and if, the first in place, there is difficulty in inserting the second, we must take out the one in place, and try again with the other first. We will thus often in a surprisingly easy manner be able to insert and to lock the blades.
7. At what Point of the Pelvis must the Blade be introduced 1—We have seen that the blades should as far as possible be applied parallel to the head, and there are a number of ways of doing so, as, for instance, he methods of Levret, Baudelocque, Mine. Lachapelle. Whatever the nettled, however, the absolute rule is never to endeavor to introduce the ?lades except during the intervals between the contractions.
A. Levrere blade is seized, like a pen, near the lock, or t the end of the handle, no matter how, according to Tarnier, provided t be convenient for the operator. The convex surface of the fenestra is ',id flat against the guiding hand at the vulva, and it is insinuated along his hand into the vagina, remembering that the latter's axis is from be )1v above, and that consequently the handle must be depressed as the lade penetrates. To recognize the posterior and the anterior blades, it laces to recall the position of the head, and the lesser curve being against hat portion of the head which must come under the symphysis, the for eps need only be locked and placed in the situation it must occupy in the clvis, in order to know which blade must be posterior, and which ante ion This little preliminary precaution, of utility in anterior positions, •ould lead us into error in posterior positions. In anterior positions we lust take as our guide the occiput, in posterior the brow, and the reason given further on.