Those conditions liable to lead to abortion are especially diseases of the chorion, placenta, and umbilical cord, rarely of the amnion, the embryo itself, or the amniotic fluid.
Chorion and Placenta.—The chorion being the nutritive organ, supplying the means of communication between mother and child in the earlier stages by the villi over its entire surface, later by the placenta, must necessarily determine the progress or cessation of foetal development by the conditions existing within its own tissues. One of the most striking and notable changes to which it is subject is the hydatiform degeneration of the villi, leading to a formation of the grape mole or hydatiform mole. This is a cystic degeneration of the terminal sprouts, an hypertrophy of the germinal tissue, the young connective-tissue cells, which usually begins at a very early stage: the vascular development is interfered with, the nutritive material is directed to the morbid activity of the chorion, which in its exuberant growth, usually inaugurated in the first weeks, destroys that of the other structures; the delicate tissues of the embryo are soon absorbed, and even the amniotic sac may disappear, the within-lying cavity, which always remains in every malformation as an unmistakable trace of the ovum—a characteristic which serves at once to mark the product of conception. A mole of this kind usually attains the size of an apple, but may grow to that of a child's head, and the period to which it is carried is much longer than that of the mola carnosa—usually five to seven months, sometimes eight or ten. The appearance is that of a conglomeration of cysts, usually the size of a currant or gooseberry, though they are often from that of a pinhead upward, connected everywhere by thin connective-tissue strands; they consist of a delicate transparent membrane enclosing a pale, colorless fluid: in the earlier stages the amnion with its cavity remains, but with the development of the growth that is destroyed, and the appearance of the hydatiform mole as a product of conception even becomes unrecognizable when no longer surrounded by the decidua; as in cases of excessive development, the morbidly-enlarged villi may even break through the decidua vera in their growth, and we find a dense mass consisting of a conglomerate of small cysts united by connective-tissue shreds enclosed in the cavity of the uterus.
Hemorrhage.—In the third or fourth month, at the time of most active development of the villi at the placental site, primary hemorrhage may occur, due to the active vascular development, and thus lead to abortion, but this is rare; frequent as hemorrhage is, it is almost invariably to be traced to some cause.
The Placenta.—In later stages, when the greater part of the chorion appears as a more firm, non-vascular membrane, that part which in connection with the decidua serotina is developed to the placental formation is the most vulnerable point, as it is the connecting link between the foetus and the maternal tissues, and the one source of nutrition. Hemorrhage in this structure, whether in its maternal or foetal portion, if excessive, must lead to a cessation of development, to abortion. Slight hemorrhages, such as must have proved fatal in the earlier stages, no longer interfere with the growth of the ovum, but are absorbed or remain as small hemorrhagic spots, the tufts or cotyledons in which they have occurred appearing as a hard whitish mass of connective tissue. If the hemorrhage is more profuse or widespread, it may lead to abortion directly or to inanition—to death of the foetus, and secondarily to abortion. Inflammation may occur throughout the entire placental site or localized, as in all other points in the connective tissue of the structure, accompanied by vascular development in the first place, followed by induration and shrinkage; frequently remaining as small irregular or conical indurations between the villi or cotyledons, leading to abortion, either by the tendency to hemorrhage thereby excited or the death of the foetus if sufficient of the tissue is destroyed to cause inanition.
Fatty degeneration occasionally results in consequence of insufficient nutrition due to hemorrhage, or after death of the foetus preparatory to premature expulsion—a morbid approximation to the condition upon its maternal surface and in the decidua serotina at term.
Syphilis.—The changes in the chorion and placental tissue accompanying syphilitic disease are rarely the direct cause of abortion or premature expulsion of the ovum; as a rule, they are mere local manifestations of the morbid condition existing in all the foetal structures, and frequently in those of the mother. In the early months, during the period of the chorion frondosum, abortion results from insufficiency of the nutriment absorbed by the indurated villi of the chorion, lacking in vascularity and in succulent embryonic tissue; the structures are more dense, the villi hypertrophied, in the more aggravated cases the vessels entirely obliterated, whilst after the formation of the placenta in later months the existence of syphilis is made evident by appearances similar to those which accompany other chronic inflammatory conditions. The appearance presented by a syphilitic placenta is usually that of cellular hypertrophy, the centre in a state of whitish induration or fatty degeneration according to the stage of the disease. But it is hardly possible to diagnose syphilis with certainty from the appearance of the placenta alone, nor is the placenta usually affected to such an extent as to appear as the prime cause of foetal death. The placenta is usually large as compared to the size of the child, in appearance similar to other inflammatory conditions presented by the placenta, the growth of the foetus being interfered with, whilst that of the placental structure continues until the retrograde metamorphosis is sufficient to result in expulsion. The placenta in a syphilitic foetus is larger than ordinary, 1 to 4, whilst usually 1 to 6. Gummata are rare, so also tumors of the placenta. A myxoma developing from the embryonic tissue is occasionally found. If the foetal portion of the placenta alone is affected, or in the earlier stages the chorion and the decidua healthy, we may with safety infer syphilis on the part of the father alone previous to impregnation.
The Amnion.—The amnion, which serves merely as a container for the preserving fluid, is wanting in vascularity, and consequently but little subject to morbid changes. The only pathological condition which we find in this structure is an inflammatory development, the formation of amniotic bands stretching across this delicate sheath or from some portion of it to the foetus, crippling or cutting its membranes in such a way as to interfere with gestation. Nor does an abundance or want of amniotic fluid affect the development of the embryo or ovum during the earlier stages. It is no more a cause of abortion than the slight changes occasionally found in the amnion itself.
The Umbilical Cord.—The navel-string, however—the sheath stretching from amnion to foetus, enclosing the umbilical vessels—is subject to quite a number of changes, frequently the cause of abortion, occasionally mere results of other complications. Excessive or insufficient length of the cord, which may seriously complicate labor at term, in no way affects the development of the ovum; in the third or fourth month the length of the cord is naturally much greater than that of the embryo, and the resulting coils and knots seem in no way to endanger its existence. Knotting of the navel-string may lead to death of the foetus, but only in the last months, rarely at earlier periods. Stenosis of one or the other of the vessels sometimes occurs, leading to the death of the embryo and consequent abortion: a condition which I have found remarkably frequent is that of torsion of a very long and thin cord in the third and fourth months; but this torsion of the cord seems so frequent in abortion that it must appear as a consequence, movement of the dead foetus apparently leading to a twisting during inactivity of the tissue. A very striking condition of the cord has frequently attracted my attention—lack of embryonic tissue, the gelatin of Wharton, with excessive torsion; the cord flat, thin, in parts thread-like, and usually very much twisted; the embryo retarded in development as compared to the size of the ovum, no other cause being at the same time discernible, neither disease of the uterus nor affection of the system. The torsion is secondary, often wanting, the cord being very thin and thread-like in places, consisting of the amniotic sheath and the vessels, obliterated entirely or in part. Torsion I believe to be secondary, as I have noticed these excessively twisted cords otherwise healthy in cases of abortion; but this peculiar state, which I cannot term otherwise than atrophy of the cord, appears as a frequent primary cause of abortion in the second to the fourth month; torsion and knots may occur at later periods. Ruge of Berlin,4 who has investigated this subject, thinks that stenosis of the cord in the vicinity of the umbilical insertion is rarely the primary cause of abortion, though often a secondary, resulting from motion and traction on the inactive, dead vessels; whilst Leopold seems to look upon it as the primary cause.
4 Zeitschrift für Gynäcol. u. Geburtsh., vol. i. 1, p. 57.
I have endeavored to call attention to the various conditions which may lead to abortion, but it is almost impossible to place an estimate upon their relative importance. Whilst uterine contractions, hemorrhage, and abortion may result in one case from a slight nervous excitement, a trifling annoyance, the most violent nervous irritation will in no way affect another; whilst a fall, a jump from a buggy, may lead to a mishap in one patient, the crushing of the abdomen beneath its wheels will not affect another; a trifling fever may appear as the cause in one, and again the most severe pneumonia or typhoid condition will not impair development in another; the child may be carried to term by a mother in the last stages of consumption, whilst a very trifling affection may lead to abortion at other times. So it is with remedies taken internally, though as a rule they have but little effect: a violent aperient may cause abortion, and again, as in one instance which I recall, a woman in the fourth month of pregnancy died rapidly of dysentery resulting from the taking of cathartic pills to produce abortion, and the post-mortem revealed a perfectly healthy ovum in a healthy uterus, whilst the dysentery consequent upon the remedy killed the mother. The careful introduction of a sound into the gravid uterus has led to a separation of the ovum, to hemorrhage, and to abortion, whilst a knitting-needle has been passed into the uterine cavity and through the womb, causing the death of the criminal mother, without in any way disturbing the ovum. The uterus has been regularly treated for supposed disease for three and five months by internal applications, and gestation has progressed. So it is with all these cases: at one time, especially with pre-existing disposition, a slight interference may result in the cessation of development, and at another the most violent insults in no way disturb gestation.