Thispresentation includes the feet, the knees, the breech, and also the hips, there being no difference in the delivery for all these parts. It is the same also whether there be one foot, or knee, or both feet and knees.
There are but two positions worthy of notice in this presentation, and they are determined by the child's sacrum. If the sacrum, or posteriors, are to the right of the mother's Pelvis, it is called theright sacro iliac position; but if they are on the left side it is called theleft sacro iliac position. The direction in which the child's pelvis is placed, is analagous to that of the head, the sacrum answering to the occiput. Thus most frequently the sacrum is on the left side, a little to the left of the pubes, (left anterior) while the abdomen faces the right side near the sacrum. When on the right side however, it is most usually nearest the sacrum, with the abdomen facing the left side near the pubes.
The lower extremities present most frequently next after the head, but still they are but seldom met with. M. P. Dubois tells us that out oftwenty thousand laborshe only met witheighty-fivesuch cases. In these eighty-five cases the breech presentedfifty-fourtimes, and the feettwenty-six, the knees being foundbut once.
A presentation of the lower extremities may generally be recognized at an early stage, by the headbeing felt at thefundusof the Uterus, and by the pulsations of the fœtal heart being heard above the umbilicus, as explained in the section on Auscultation. After labor has commenced the part felt at the mouth of the Womb is irregular, and so different from the head, that it is not likely to be mistaken for it. If the knees or feet present, they can always be distinguished; and if the breech presents it can easily be recognized by its form, and particularly by the os coccygis, which can be distinctly felt at the bottom of the depression between the two cheeks. The side on which it is felt of course determines the position, and the same with the front of the knees, or the heels. The Rectum can also be reached with the finger, when the breech is touched; but great care must be taken not to intrude it too far, because with a female child theVulvamight be mistaken for it, and thus the hymen be broken, and other injury committed. The genitals of a male child are more obvious, so that the sex of the child may be usually ascertained, along with the position.
For want of proper care the breech has been mistaken for the head, and face, but this can scarcely happen if the accoucheur is attentive. It is simply necessary to call to mind whatmustbe felt in each presentation, as thenoseandmouthwith the face; the two cheeks of the posteriors, with the opening between them; and also the genitals, with the breech; and it can be certainly ascertained which of these parts are really at the opening. With the knees or feet there can scarcely be a doubt.
In this position the legs and thighs are turned upagainst the abdomen, the breech in full occupying the passage, with the sacrum to the left and in front of the mother's pelvis.
The descent of the breech usually takes place without much difficulty, into the Pelvis, it being small and easily compressed. It descends in the same direction in which it first presents—that is diagonally, like the head—and also rotates, or turns round, so that the left buttock comes in front, just to the right of the pubis, while the right one goes behind, to the left of the sacrum. The left buttock reaches the mouth of the Vulva first, in this position, and then remains stationary there while the right one slides along the curve of the sacrum and perineum, and passes out first at the lower part of the external opening. The left however, speedily follows, and when the whole breech is born it rotates again, one hip coming immediately in front, and the other going immediately behind. Owing to this movement the long diameter of the breech is adapted to the long diameter of the Pelvis, as in the case of the head. This will be evident from the following Plate:—
PLATE XXXII.Delivery in a breech presentationDelivery in a breech presentation, the buttocks having just passed the Vulva.c.The Coccygis, much straightened.p.The pubic bone, in front.
PLATE XXXII.
PLATE XXXII.
Delivery in a breech presentation
Delivery in a breech presentation, the buttocks having just passed the Vulva.c.The Coccygis, much straightened.p.The pubic bone, in front.
Delivery in a breech presentation, the buttocks having just passed the Vulva.
c.The Coccygis, much straightened.p.The pubic bone, in front.
The rest of the body then rotates in the same way, and the arms and shoulders pass through the external opening in the same direction as the hips. The left shoulder first moves to the right of the pubes, while the left passes behind; and then, just when they are both passing out, one comes immediately in front, and the other immediately behind, placing themselves in the long diameter of the Vulva.
The head passes through the superior strait in the left, anterior occipital position, and is often delivered in that way; but sometimes it rotates, and the forehead passes into the curve of the sacrum, while the occiput is placed behind the pubes. When this occursthe body also rotates, to accompany the head. This state of the parts is represented in the following Plate:—
PLATE XXXIII.Anterior posterior positionAnterior posterior position of the head, the occiput being in front, after the delivery of the body.c.The Coccygis.p.The pubic bone, in front.
PLATE XXXIII.
PLATE XXXIII.
Anterior posterior position
Anterior posterior position of the head, the occiput being in front, after the delivery of the body.c.The Coccygis.p.The pubic bone, in front.
Anterior posterior position of the head, the occiput being in front, after the delivery of the body.
c.The Coccygis.p.The pubic bone, in front.
At this period the head is passed the uterus, and there is therefore little or no contraction to expel it, so that it often remains a long time undelivered. It will be seen that the position is very unfavorable, the longest diameter of the head, the occipito frontal, being the presenting one, which makes it lie immoveably across. The means of assisting in such a case are plain enough, the forehead must be brought down while the body israised, towards the mother's abdomen; this will throw the top of the head back, towards the sacrum, and change the presenting diameter.The forehead and bregma rapidly escape below, and the occiput passes out last. This is the way in which nature herself also completes the delivery in such cases, when she has the power.
This position is the reverse of the preceding one, the Sacrum being behind, and to the right, while the Abdomen is to the left in front. The same movements are performed as in the first position, and the whole process is similar, only the reverse way. The Sacrum being behind however, has to rotate much further to come in front, precisely the same as with the head when in the posterior position.
The head generally follows the Sacrum, and the occiput comes under the pubes, as already explained; but sometimes only at the moment when being disengaged.
In this position there is no rotation at all, the back of the child being turned full to the back of the mother, and the whole body, and head, being expelled in that position. In general there is no particular difficulty from this position, but on the contrary it is thought by some to be rather favorable than otherwise. The longest diameter of the fœtal pelvis, and shoulders, are adapted to the longest diameter of the mother's pelvis, at the upper strait, and easily pass it. They will also generally pass the external opening in the same direction, unless it be very unyielding,or the child very large; and if they pass the head usually follows, because the parts have been so much dilated by the passage of the body that they offer but little resistance.
As a general rule delivery by the breech, or by any other position of the lower extremities, is less favorable than by the head. The labor is usually longer, more painful, and more exhausting; still however, it is generally spontaneous, and not necessarily dangerous to the mother. To the child, on the contrary, it is dangerous, on many accounts.
It appears, from the observations of M. P. Dubois, that in this presentationone child is lost out of every twelve, while only one out offiftyis lost in head presentations! The chief cause for this greater mortality appears to bethe compression of the umbilical cord, which is greater, and lasts much longer, than when the head presents, as will be evident on examining the circumstances under which delivery is effected in each case. When the head presents it passes, and also the shoulders, before the umbilicus is reached; the mother's organs are therefore much dilated, and only the smallest parts of the fœtus are left, when the cord is engaged in the passage; it cannot therefore be much compressed, nor for any long time, because the labor is then soon over. When the lower extremities present this is not the case, thesmallestparts then pass before the umbilicus is reached, so that the cord has to pass along with the head and shoulders, which are both the largest and the longest in being delivered. Thiscompression of the cord stops the circulation of blood between the fœtus and the Placenta, as will be evident on referring to the description formerly given ofFœtal nutrition; and the stopping of this circulation is as fatal, to it, as stopping the breath is to an adult. When the breech presents altogether, there is not so much danger as with the feet, or knees, because it is large, and in its passage dilates the parts so much that the rest of the body, and the head, follow more quickly. There is, of course, no danger till after the hips have passed, because the cord is not reached before; but the delivery should be completed as soon after they are born as possible, for every minute's delay makes the chances for the child's life so much less.