In order that the column of water be sustained, the sides of the tube must be rigid or unyielding. If the sides of the tube yielded slightly to atmospheric pressure, they would sink in and a certain amount of water would escape.

The abdominal and pelvic cavities in the erect woman may be considered as a tube filled with fluid contents. The top of the tube is closed by the diaphragm; the sides are the more or less rigid abdominal walls and the back; the floor is the perineum. When the floor is destroyed a hole is made in the bottom of the tube: the contents tend to fall, but the fall is resisted by atmospheric pressure acting from below. If the diaphragm and the parietes were rigid as glass, there would be no prolapse, any more than there is prolapse of the water in the glass tube. If the parietes yield somewhat, the amount of fall or prolapse is proportional. Thus the retentive power of the abdomen is dependent upon the strength or rigidity of the abdominal walls.

CHAPTER IX.

PROLAPSE OF THE UTERUS.

PROLAPSE of the uterus means a falling of that organ below its normal level. The condition is popularly spoken of as "falling of the womb." There are an infinite number of degrees of prolapse of the uterus, between the slightest descent on the one hand and complete protrusion of the organ from the body on the other hand. The term "complete prolapse" should properly be applied to the entire protrusion of the uterus outside of the vulva. This condition, however, is most unusual. The term is generally used to designate those cases in which the cervix alone, or the cervix and part of the body of the uterus, protrude from the vulva (Fig. 66). In any case of prolapse of the uterus it is best to describe in detail the extent of the prolapse and the other conditions present. Thus, some of the various kinds of prolapse may be described as follows: "Prolapse of the uterus, the cervix resting on the pelvic floor;" "prolapse of the uterus, the cervix presenting at the vulvar cleft;" "prolapse of the uterus, the cervix protruding about two inches from the ostium vaginæ, with elongation of the supra-vaginal cervix," etc.

Injury to the pelvic floor that allows air to enter the vagina destroys the normal equilibrium of the pelvic contents and exposes the uterus to a direct abdominal pressure from above, which is not counterbalanced by an equal force from below, but is opposed by the strength of the uterus and its attachments and the retentive power of the abdomen. Most cases of prolapse occur in women in whom the perineum has been injured at childbirth.

There are a number of predisposing causes of uterine

prolapse that permit the descent to progress after the uterus has begun to fall-namely: Relaxation of the uterine ligaments that results from too frequent parturition, from old age, or from tissue-weakness which is part of a general condition, the uterine ligaments sharing the general feebleness of the other tissues and structures of the body; relaxation, loss of rigidity, or muscular

weakness of the abdominal parietes, which diminishes the retentive power of the abdomen; diminution of the cellular tissue and the fat of the pelvis, such as occurs in wasting disease or in old age. Anything that suddenly increases the intra-abdominal pressure, such as lifting a heavy weight, may cause acute prolapse of the uterus. In some cases the uterus has suddenly protruded from the body as a result of heavy lifting. In cases of this cha

racter it is probable that the muscular supports of the perineum have been weakened from some cause, or that the sudden increase of abdominal pressure drives the uterus downward before the perineal muscles have time to contract and close the vaginal outlet. In such cases there is also present rupture of the uterine ligaments. Constant violent coughing has produced uterine prolapse in a similar way.

Extreme uterine prolapse sometimes occurs in a nulliparous woman in whom the perineal supports are naturally weak. In such women there exists a condition of relaxation identical in results with subcutaneous laceration of the perineum.

Anything that increases the specific gravity of the uterus will make it sink somewhat lower in the pelvis. Subinvolution, congestion from inflammation, or retroflexion may do this. In such cases, however, the prolapse never becomes extreme, rarely extending beyond a slight sinking of the uterus.

In most cases uterine prolapse takes place slowly. Sometimes many years are necessary for the development of complete prolapse. The equilibrium of the pelvic contents is destroyed by one of the causes already mentioned. The uterus falls through a certain distance before the uterine ligaments become suspensory. Then, however, its further descent is impeded.

If the original cause continues to act, the uterine ligaments become stretched and the descent of the uterus gradually progresses, impeded to a varying degree also by the retentive power of the abdomen and the cellular tissue and other pelvic attachments.

As the uterus descends, the vaginal walls attached at the cervix are dragged down with it, so that when the prolapse becomes complete the vagina is turned inside out (Fig. 67).

When the perineum has been injured so that the lower portion of the vagina loses its support and the equilibrium of the pelvic contents is destroyed, two distinct

phenomena occur: The uterus falls as already described, and at the same time the lower part of the vagina begins to fall, so that there appear a prolapse of the anterior vaginal wall, or a cystocele, and a prolapse of the posterior wall, or a rectocele. The condition finally produced will

FIG. 67.-Complete prolapse of the uterus.

depend upon which prolapse takes place the more rapidly-that of the vagina or that of the uterus.

If the prolapse of the lower vagina progresses faster than that of the uterus, then the vagina will begin to drag upon the cervix, to which it is attached, and under these circumstances the uterus will be subjected to two downward forces-intra-abdominal pressure from above, and traction of the vaginal walls acting from below.

As the traction is exerted upon the lower part of the cervix, and the body of the uterus is sustained by the uterine ligaments, which resist the downward traction, the isthmus, or point of junction of the body and cervix, is dragged out or stretched, so that in some cases a very