CHAPTER IV.
MOLE PREGNANCY.
Nature and origin.—Varieties.—Diagnostic Symptoms.—Treatment.
When any cause has occurred to destroy the life of the embryo during the early weeks of pregnancy, one of two results follows, either that expulsion takes place sooner or later, or the membranes of the ovum become remarkably changed, and continue to grow for some time longer, until at length they form a fleshy fibrous mass, called mole, or false conception.[47]
It is well known that the venous absorbing radicles of the chorion, which give it that shaggy appearance during the first months of pregnancy are the means by which the embryo is furnished with a due supply of nourishment at this period: if the embryo should die from any cause, and the uterus show no disposition to expel the ovum, the nourishment which has been collected by the absorbing power of the chorion appears now to be directed to the chorion itself, which therefore puts on a fleshy growth and increases very rapidly in size. (Rœderer, Elementa Artis Obstetricæ, p. 738.)
In other instances, the thick fleshy character of the ovum is not produced by a growth of substance, but is the result of hæmorrhage from rupture of some of the vessels which run between the uterus and the ovum. In this case, if the placental cells be already formed, they become distended with the blood of the hæmorrhage which solidifies by coagulation; and not only render the chorion or incipient placenta much thicker and more solid, but give it also a lobulated tuberculated appearance: from the same reason, the little funis, which is probably not an inch long, is greatly distended, being in some cases as thick as the body of the embryo itself, the blood having penetrated from the placental cells into the cellular tissue of the chord. This is by no means an uncommon form of mole; externally it is covered by the decidua, which appears to be in a natural condition, and the inner surface of the cavity is lined by a fine membrane, having all the usual characters of the amnion. The lobulated appearance is chiefly seen from within, the amnion being raised by a number of irregular convexities.
“When the blood is poured out from its containing vessels into the substance or cells of the placenta, or between the membranes, gradually coagulates, and assumes a very dark purple, and sometimes almost a melanotic black colour: after a time, however, it begins to lose this tint, the colouring matter gradually becomes removed, and the coagulum successively assumes a chocolate brown, a reddish or brownish yellow hue; and latterly, if time sufficient be allowed, it presents a pale yellowish white or straw-coloured substance, the fibrinous portion of the coagulum being then left alone.”[48] This form of mole, as far as our own observation goes, seldom attains any considerable size, rarely exceeding four inches in length, and is usually expelled between the eighth and twelfth week. The size and condition of the fœtus varies a good deal; in some cases it appears nearly healthy, although the cord is much thickened and distended; this is probably owing to its having been expelled shortly after its death, or to its having gone on to live a short time after the injury which had caused hæmorrhage: in this way alone can we explain why we occasionally meet with cases where the parietes of the ovum are much thickened and solidified, and yet the embryo is in such a state of integrity as to prove that its death must have been very recent. The extravasation of blood between the ovum and uterus does not appear to be sufficient to annihilate immediately the nutrition of the embryo, so that the blood has had sufficient time to solidify before the ovum was expelled. At other times the embryo exhibits evident marks of having been dead some time: it is much smaller and younger in proportion to the size of the ovum; sometimes it has disappeared entirely, a short rudiment of the funis merely remaining to mark its previous existence.
“Should the embryo die (suppose in the first or second month) some days before the ovum is discharged, it will sometimes be entirely dissolved, so that when the secundines are delivered, there is nothing to be seen. In the first month the embryo is so small and tender, that this dissolution will be performed in twelve hours; in the second month, two, three, or four days will suffice for this purpose.” (Smellie.)
Where the growth of the ovum proceeds after the destruction of the embryo, it increases very rapidly in size, much more so than would be the case in natural pregnancy, so that the uterus, when filled with a mole of this sort, is as large at the third month as it would be in pregnancy at the fifth.
Another form of mole is where the uterus is filled with a large mass of vesicles of irregular size and shape like hydatids, which appear to be the absorbing extremities of the veins of the chorion distended with a serous fluid; it is difficult to distinguish these from real hydatids; the more so, as Bremser asserts that he has occasionally met with real hydatids among them. Perhaps the mode of their attachment will in some degree assist the diagnosis: these vessicles, or hydatids of the placenta, as they have been called, are attached over a large portion of the uterus,—an arrangement we believe, not generally seen in real hydatids, which are mostly attached to a single stalk or pedicle. Indeed, it may be doubted if the masses of vesicles which are occasionally expelled from the uterus are ever true acephalocysts, as they are invariably connected with a blighted ovum, and are, therefore, formed as before observed, by a dropsical state of the venous radicles of the chorion.