DISEASES OF TIIE AMNION.
Like the decidua and the chorion, the amnion is subject to various lesions ; but there is one of more importance than all the others from its influence upon the mother and the fistus. We refer to what is known as dropsy of the amnion or hydramnion.
Dropsy of the Amnion.
Dropsy of the amnion, or hydramnion, consists of an exaggerated collec tion of fluid in the amniotic cavity. As Guillemet remarks, it is difficult to fix the limit at which the amount of the liquor amnii becomes morbid, since it varies considerably in a state of health. It is, therefore, from the phenomena that result therefrom that, in the absence of any precise point of departure, we decide what is dropsy of the amnion. But these phenomena themselves vary with the individual, and with the rapidity with which the secretion accumulates; so that an arbitrary limit has been fixed upon, and all authors agree that when the quantity of the fluid ex ceeds 32 to 48 ounces there is dropsy of the amnion.
we followed the statistics we should hold that hydram nion is rare, occurring hardly once in 100 to 150 confinements; but it is really far commoner. Typical cases, with enormous accumulation of liquor amnii are rare, it is true, but a relative abundance is often seen, the ordinary cases passing unnoticed; for the accidents that occur from it depend more upon the rapidity of accumulation than upon the amount of the fluid. This accumulation is usually slow and progressive, and is well borne; but sometimes the effusion is more rapid, and the womb, forced to distend itself suddenly and exoessively, rebels, and gives rise to certain peculiar symptoms. Jacquemier and Oulmont only have carefully studied these cases. We ourselves have seen two, which are described, together with those which we have been able to collect, in our memoir on hydram nion, 1880.
Etiology.—We must now return to the theories as to the origin of the liquor amnii. The theories concerning it may be reduced to three: 1st.
It is of ketal origin; 2d. It is of maternal origin; 3d. It is of fcetal and maternal origin.
1st. 77Le liquor antnii is of petal origin.--We may dismiss the ridicu lous theories of Bohn, who derives it from the mammary glands; of Lis ter, who draws it from the salivary glands; of Warthon, who believed that it was a product of the gelatinous matter of the cord, and even of the lachrymal glands. The following hypotheses are possible: a. The liquor amnii is due to secretion from the skin; b. It is due to secretton from the kidneys; c. It is due to a transudation of the liquid parts of the fcetal blood, through the amniotic-membrane; d. It is a peculiar secretion of the amnion.
a. 7'he liquor atnnii is secreted by the skin.
This theory originated with Galen. Scherer says that since the vernix caseosa has the same composition; since Schwann found pyine in the fcetal skin, and Eicholz mucous matter in the new-born at term; since the umbilical cord produces a larger quantity of water than its return vessels can carry away; that, therefore, the fcetal skin excretes a watery fluid. Nevertheless, the liquor amnii is not exclusively produced by the skin, and the presence of the various materials in the amniotic fluid is due to a simple mixture.
Schatz attributes a considerable influence to the skin upoil the forma, tion of the liquor amnii during the latter half of pregnancy. The high temperature to which the fcetus is subjected causes excessive secretion of the sweat, and the liquor amnii contains the constituents of that secre tion. During early intra-uterine life, before tbe sudoriporous glands are formed, the liquid parts of the fcetal blood transude through the integu ment. Bar denies this, since Ile never found ferrocyanide of potassium, injected into the reins of a pregnant rabbit, in the liquor amnii.
b. The amniotic fluid is due to the urinary secretion and to the excretion of the urine by the pelts into the atnniotic cavity.