We may, therefore, state that the causes of arm or shoulder presentations are of two kinds, viz. where the uterus has been distended by an unusual quantity of liquor amnii; or where, from a faulty condition of the early pains of labour, its form has been altered, and with it the position of the child.
It is a well-known fact that cross births, as they have been called, are frequently preceded by severe spasmodic pains in the abdomen, from which the patient suffers for some days or even weeks before labour has commenced: the uterus is more or less the seat of these attacks, which usually come on towards night-time; and, in some instances, it is felt for the time hard and uneven from irregular contraction. It was the circumstance of this symptom having preceded five successive labours of a patient, in all of which the child had presented with the arm or shoulder, which induced Professor Naegelé, when attending her in her sixth pregnancy, to endeavour to allay these cramp-like pains, which had begun to show themselves as severely as on former occasions. Having tried opium by itself, and also in combination with ipecacuanha or valerian without effect, he ordered her a starch injection with twelve drops of Tinct. Opii every night as long as she continued to suffer from these attacks: the spasms soon ceased, nor did they appear again during the remainder of her pregnancy, and he had the satisfaction of delivering her at the proper time of a living child, which presented in the natural manner.
Many other causes of malposition have been enumerated by authors, which evidently exist only in theory and not in reality: thus, shortness of the umbilical cord, or its being twisted round the child, insertion of the placenta to one side of the uterus, faulty form or inclination of the pelvis, obliquity of the uterus, as above-mentioned, violent exertions or concussions of the body, plurality of children; of all these, we do not believe that there is one which can exert the slightest influence in determining the position of the child. There is no doubt that several of them will render labour difficult or even dangerous, more especially deformed pelvis; but we constantly meet with it under every degree and variety without at all altering the child’s position. Indeed, if malformation of the pelvis were to be a cause of malposition of the child during labour, what difficulties would it not add to the process of delivery under such circumstances? And yet we find, with very rare exceptions, that in every case requiring artificial assistance on account of contracted pelvis, the head is resting upon the brim which is too narrow to allow it to pass.
We may also mention another circumstance which has occasionally seemed to produce a faulty position of the child. It sometimes happens that the hand, which is frequently felt lying by the side of the face at the beginning of labour, instead of slipping up out of reach as the head descends, which is usually the case, advances more and more, until it not only prevents the head from engaging farther into the pelvis, but pushes it out, so that the head slips up to one side, and lodges in the cavitas iliaca, allowing the shoulder with the rest of the arm to descend.
Where, however, the pelvis is large or the head small, the arm will not always force it to one side, but the two will come down together and be born in this position. (See case in our Midwifery Reports, Med. Gaz. April 19, 1834.)
Sometimes the two hands present (La Motte, book iii. ch. 26.,) or a hand and foot: this, however, does not long continue so, for when the membranes have ruptured, the liquor amnii flowed away, and the uterus contracted upon the child, one shoulder and arm descend before the rest, and remain in this position.
The complication of two arms presenting with the head we disbelieve entirely, except where it has been made during some awkward and ignorant attempts at delivery.
Although the symptoms of malposition of the child during the last few days before, or at the commencement of labour, are far from being distinct, still, however, when taken collectively, they will be sufficient to excite our suspicion. The abdomen is irregularly distended, and marked with unequal prominences; anteriorly, it is more or less pointed. It is usually much increased in breadth, and this is generally in an oblique direction, forming a globular protuberance at the upper part on one side, and at the lower part on the other: the former is the pelvic extremity of the child; the other, from its size, form, and hardness, may easily be recognised as the head.
“The movements of the child feel differently to what they did before; they are no longer exclusively confined either to one side or the other. Sometimes, as before-mentioned, cramp-like pains are felt in the abdomen, during which it is more or less distorted with violent movements, apparently of the child, as if it were trying to force its way through the abdominal parietes at this spot.” (Naegelé, Lehrbuch, p. 223.)
Upon examination per vaginam, either no presentation is to be reached at all, or only small parts can be indistinctly felt, such as the hand, the arm, or the shoulder. The not being able to feel a presenting part in a primipara shortly before or at the commencement of labour, is an unfavourable symptom; for the head at this time ought to be deep in the cavity of the pelvis; still, however, it does not necessarily prove that the child is presenting wrong, for it may be a presentation of the nates, which, as we have before shown, do not descend so low into the pelvis just before labour, as the head does; or it may arise from the unusual size of the child’s head, especially in cases of congenital hydrocephalus. It may arise from a large quantity of liquor amnii, and where the head is nevertheless presenting; it may be a case of twins, or lastly of dystocia pelvica, where the head is presenting, but unable to pass through the contracted brim.