PRESENTATIONS AND POSITIONS OF THE FŒTUS.
Thechild may present several different parts of its body, at the commencement of delivery, and they may be in different positions relatively to the different parts of the Pelvis. All these require to be known.
Different authors have made different classifications of the presentations and positions, and have differently named them; but this is of little consequence, since they are still the same, no matter how they are named. I shall follow the arrangement of M. Chailly, because I think it equally perfect, and much more simple and practical, than any other yet proposed.
The fœtus may present at the mouth of the Womb either by thehead, the most usual way—by the lower extremities, which is the most frequent way after the head—or by various parts of the trunk, which is the least frequent way of all.
In each of thesethreefull presentations there may be certain variations, which require to be noticed. The head, for instance, may present either by thecraniumor by theface; the lower part of the body may present either by thefeet, theknees, or thebreech, according as the legs and thighs are flexed or extended; and the trunk may present either on therightorleftside, and inclined towards thebackortowards thechest, though neither the back nor abdomen ever fully present.
Each of these variations may also have slight variations again. Thus the face may present full, or by one or the other cheek, and so on. These variations however, are of little practical consequence, because we only find them at the very commencement of the labor, and they always change to the full presentation.
Practically speaking therefore, there arefive full presentations, viz.,the Cranium,the Face,the Breech,the Feet, or knees, and theTrunk, either by the right or left side.
Thevarietiesof these, as already remarked, not requiring any special attention from the accoucheur, providing he is not puzzled or misled by them.
The position means the particular direction in which the presenting part of the Fœtus is placed in relation to the Pelvic straits. The Pelvis itself is supposed to be divided into two similar halves, therightand theleft, and each presenting part has one particular place which is referred to as the indicating point. Thus, for instance, in the Cranium the Occipit, or behind part of the head, is the indicating point; and we therefore say, in Cranium presentations, that it is aright or left Occipital position, according as the back of the head is to the right or left side of the Pelvis. In face presentations, the chin (mentor) is the indicating point, and we therefore say it is aright or left mento position, according as the chin is towards the right or left side. In breech presentations, the child's sacrum is the indicatingpoint, and we then say it is aright or left sacral position, according as the Sacrum is towards the right or left side of the Pelvis. In trunk presentations, which are always crosswise, the head (cephalo) is the indicating point, and we therefore say it is aright or left cephalo position, according as the head lies towards the right or left side of the mother's body.
In Cranium presentations also, the back of the head is not merely on the right or left side, but may be at two different points on each side. It may be either nearest to the Sacrum (posterior), or nearest to the pubes (anterior), but still against the Ilium; it is therefore called aright or left anterior,or posterior,occipito iliac position, as the case may be. Sometimes also, the occiput lodges immediately on the pubis, instead of going to either side, and that is called anoccipito pubic position; at other times, on the contrary, it is placed against the Sacrum, instead of being on either side, and that is called anoccipito sacral position.
In presentations of the head therefore, we may reckonsixpositions—the right and left anterior and posterior occipito iliac, and the pubic and sacral.
In presentations of the face the same; they beingmentoiliac and so on, instead of occipito.
In presentations of the lower extremities also the same, excepting that they aresacroiliac and so on, instead of occipito.
In presentations of the trunk we have but two positions for each side, the right and left cephalo iliac; according as the head is on the right or left side of the mother's body. The child always lying, in presentations of the trunk, crosswise—the feet on one side and the head on the other.
Most authors enumerate many more presentations and positions, but they are of little practical utility. When the head presents, for instance, the delivery takes place in nearly the same manner, let it be in what position it may. And in presentations of the face, or of the lower extremities, the particular position is of little consequence, the delivery being usually effected much the same in them all. Some of the positions are, it is true, much more favorable than others, but a spontaneous delivery, generally speaking, occurs in all of them, when the head, face, or lower extremities presents. Very frequently indeed, the less favorable positions are changed to the more favorable ones, and the worst seldom do more than impede delivery for a time, unless there be some malformation, or loss of power. I therefore refer to them more for convenience in future explanations, and to enable my readers to know what is meant by them, when they read other books; not because they are really necessary to be understood, or of any great practical use.
The celebrated Baudelocque admittedseventy-four positions, andtwenty-two presentations; and the number might be made still greater, if all the variations were to be enumerated. Such classifications however, are more ingenious than useful, and they are but little noticed even by medical men.
I shall merely describe the mechanism of labor in the most frequent positions, in each presentation, because the others usually change into these; and even when they do not, the process of delivery is essentially the same, and also the mode of assisting it.
The Presentation.—Although in general it is not possible to ascertain with certainty, what part of the fœtus presents to the mouth of the Womb, until labor commences, yet a tolerable judgment can frequently be formed before. In head presentations, on performing ballotment, the head is felt, like a firm round tumor, occupying all the space which the finger can reach, very differently from any other part. The peculiar cramps in the female's lower limbs, and frequent inclination to urinate, mentioned in the signs of labor, are also strong indications of this presentation, being seldom experienced in any other. When the labor has actually commenced there can be but little uncertainty in these cases, for, immediately the mouth of the Womb is sufficiently open, the finger can be introduced, and the head felt like a smooth, round, and elastic bony tumor, not likely to be mistaken for anything else, if ordinary care be taken. After the waters have escaped, it can of course be felt still more distinctly. If even an inexperienced person bears in mind theshapeof the head, and reflects how it mustfill upthe passage, and how it must feel, from being composed of separated thin bony plates, lying on a soft yielding substance like the brain, he can scarcely fail to recognize it. The sensation is very much like that of pressing a piece of firm card board on an inflated bladder, which forms a tolerable representative of the fœtal head. Sometimes there is a difficulty from a great quantity of water being intruded between the membranes and the head, which somewhat obscures the touch, but this only necessitates greater care. Thewater however, may be in such quantity as to entirely prevent the touch, in which case nothing can be done till the membranes break; the presentation can then be ascertained with certainty, and it will be quite early enough to render assistance, if it should be an unfavorable one. I have known some inexperienced persons mistake the bag of water itself for the head, and commit great errors in consequence.
The Face can seldom be mistaken, because the nose, or mouth, may be felt; and, by passing the finger up the side of the head, the ears also.
The trunk is in general easy of recognition. Nearly always the right or left shoulder occupies the passage, or is near to it, so that the finger may be readily passed under the arm pit. The shoulder joints, the ribs, or the shoulder blade bone, all feel very different to the head, and are not likely to be taken for it.
In presentations of the lower extremities there is still less danger of error. If the feet, or knees, occupy the passage, they can scarcely be mistaken. The breech is certainly something like the head in its form, but feels different, and is divided down the middle by the indentation between the two cheeks, along which the finger can be passed till it enters between the limbs.
In irregular presentations, as of the arms for instance, or of one leg, or an arm and leg, it is only necessary to carefully feel them, so as to ascertain their form, and the relation of their parts. Thus the fingers can be distinguished from the toes, and the feet from the hands, particularly if the ankle can be felt.
The accoucheur should ascertain the particular presentationas early as possible, because he maysometimes be of service in correcting an unfavorable one, if he is certain of it in time, and knows what he is about. He should not however, use any degree of force to ascertain it, in case he cannot do so without, but wait till the conditions are more favorable. Neither should he, with the same object, rupture the membranes too soon, for he may thereby cause considerable delay and difficulty, without any good to counterbalance it.
All the above-named presentations may, and usually do, terminate spontaneously, except those of the trunk, and even they do occasionally, though more frequently they require assistance.
Relative frequency of the different presentations.—The most favorable presentations, and positions also, are always the most frequent, while the unfavorable ones are but seldom met with. According to Madame Lachapelle, infifteen thousand six hundred and fifty-two laborsthere are aboutfourteen thousand seven hundred and forty-ninepresentations of the head and face; aboutfive hundred and eighty-sixof the breech, knees, and feet; and only aboutsixty-eightof the trunk, or shoulders.
Positions.—The position is generally of but little consequence, because in all the favorable presentations spontaneous delivery occurs in every position alike, and in the unfavorable presentations the same assistance is required in one position as in another. In some cases an unfavorable position of the head may be changed however, to a better one; and therefore, so far as the head is concerned, the positions are worth ascertaining.
The mode of determining the position is by feeling for thesuturesandfontanelles, described in Chapter VIII; and this cannot be usually done till after themembranes are broken, when the head can be distinctly touched. By referring to Plate XXIV, the shape and position of the Fontanelles will be seen, and if the head be supposed placed with the top downwards, and the back of it to the mother's left side, they may be readily found with the finger.
In the left anterior occipito iliac position, or that when the back of the child's head is against the left side of the mother's pelvis, and nearest the pubes, while its forehead is against the right side, and nearest the sacrum,—the sagittal suture, or opening along the top, will of course run across from right to left. This opening may be distinctly felt with the finger, which should be passed along it towards the right side, and it will then reach theanterior fontanelle; afterwards it should also be passed to the left side, and then it will reach theposterior fontanelle. The difference between these two openings, in shape and size, is shown in Plate XXIV, and even if a person has never seen, or felt, the head of a newborn child, they can scarcely be taken for each other, after noticing that Plate.
If the anterior fontanelle should be felt on the left side instead of the right, and near the pubes, while the posterior fontanelles is to the right, and near the sacrum, the position must be theright posterior occipito iliac, or just the reverse of the former.
If the sagittal suture should be found to run across from the pubes to the sacrum, instead of from one side to the other, it will then indicate either an occipito pubic, or occipito sacral position, according as the back of the head is behind or before; and this can be readily ascertained by finding either of the fontanelles.
In short, if the relative position, forms, and directionsof these openings in the child's head be clearly understood, the position of the head can nearly always be determined by feeling them, as will be evident by referring to our former explanation of them.
Sometimes however, the bones overlap a good deal, from the head being pressed, and then instead of an opening along the top, aseamwill be felt. And sometimes, from long continued pressure, a quantity of blood, and watery fluid, will be effused under the scalp, so as to prevent the bone being distinctly touched. But these accidents seldom happen, and with ordinary care and perseverance, need not prevent the position being determined, after a little delay.
The position of other presenting parts is easily ascertained, by feeling for some known point—as thenose, or the face, the depression between the cheeks, or the breech, and so on.
Relative frequency of the different positions.—The most favorable positions, like the most favorable presentations, are also the most frequent. According to Baudelocque, inten thousand three hundred and twenty-two cases, of head presentation, there wereeight thousand five hundred and twenty-twocases when the back of the child's head was on the mother's left side, and towards the front, (or in the left anterior occipito iliac position);one thousand seven hundred and fifty-fourwhen it was on therightside towards the front, (right anterior occipito iliac);twenty-five timesto the right side, but towards the Sacrum, (right posterior occipito iliac); andnineteen timeson the left, but towards the Sacrum, (left posterior occipito iliac.) Being most frequently with the back of the headtowards the front on the left side, as shown in Plate XXVII; next towards the front on the rightside; and but seldom towards the Sacrum, or back, on either side. In all these ten thousand cases we do not find a single instance of the head lying from back to front, in theoccipito pubic, oroccipito sacralpositions, commonly called transverse; neither do we find a single instance infifteen thousand six hundred and fifty-two casesrecorded by Madame Lachapelle; which will show how rare such unfortunate positions must be. What this great frequency of one particular position depends upon we do not know—possibly on that cause, previously alluded to, which determines the most frequent presentation.
In the next Chapter, the mechanism of delivery, or the manner in which the child escapes out of the body, as it most frequently occurs, will be fully explained.