Prolapse of the uterus ordinarily called "falling of the womb" is a condition in which the uterus permanently occupies a lower level in the pelvis than is normal (Figs. 37, 38). This condition varies in degree from the slightest appreciable descent to that state in which the uterus is entirely without the pelvis and hangs between the thighs of the patient. In this case the vagina is turned inside out. In the majority of cases the cervix is above or just within the vaginal orifice. Often, however, it protrudes beyond the vulva. Different degrees are recognized, as first, when the cervix remains within the vagina; second when the cervix protrudes beyond the vaginal orifice, and third when the uterus is outside of the pelvis. When the uterus remains within the vagina it is called "incomplete'' prolapse and when it is outside the vagina it is called "complete" prolapse or "procidentia uteri."

Fig. 37. Degrees of Incomplete Prolapse.

Fig. 38. Complete Prolapse.

Of the several agencies retaining the uterus in normal position, the tissues forming the pelvic floor, the levator ani muscle, in particular, is of chief importance. It, more than any other single factor, opposes the action of gravity and intra-abdominal pressure and prevents the descent of the uterus. This is due largely to the position of the uterus relative to the opening in the muscle through which the vagina passes. The cervix overlaps this opening in the direction of the sacrum and the fundus in the di rection of the symphysis pubis so that the uterus extends beyond the opening in both directions, (Fig. 1) posteriorly and anteriorly. To allow prolapse of any considerable degree the cervix must either be brought forward or the opening must be enlarged so as to allow the cervix to slip into it. In all cases of prolapse of any considerable degree the cervix will be found anterior to its normal position. Complete prolapse is restrained, but not prevented, by the round and broad ligaments.

There is a very common form of descent of the uterus which according to the classification of our text books can hardly be called "prolapse." A term of my own choosing is "settling" of the uterus. The uterus is lying heavily in its bed. The cervix and fundus are directed normally, the cervico-corporeal angle is unchanged. The relation of the uterus to the opening in the levator ani is undisturbed, its mobility under bimanual examination is either unaffected or slightly increased, but its normal respiratory excursion is limited and sluggish. It is congested, heavy and enlarged and lies lower in the pelvis than is normal. This is usually a part of a general visceroptosis.

Causes

(1.) Childbirth. The liability to prolapse is proportionate to the number of children a woman bears. Each parturition adds its own liabilities. Only about one per cent of cases of prolapse occur in women who have never borne children. This with its sequelae is one of the most important causes of prolapse. It is often followed by perineal lacerations and when these involve the levator ani, prolapse is almost inevitable, sooner or later. Even when the laceration is not so extensive it may allow the formation of a cystocele which in turn draws the cervix forward and downward. Should the woman escape a perineal laceration, subinvolution with its consequences may ensue. The uterus may not only be left larger and heavier than normal but its ligaments, the pelvic floor, the abdominal walls, may at the same time be left relaxed, and weakened, and less capable of sustaining the heavier uterus. Subinvolution or relaxation of the pelvic floor is next in importance to laceration. If the levator ani does not regain its tone after each parturition the vaginal opening through this muscle having been stretched enormously in labor remains large, relaxed and patulous. The cervix easily slips forward into it under the influence of increased intra-abdominal pressure and a prolapse occurs. Under these conditions the subinvolution has involved the uterus also and its increased weight facilitates the prolapse. Lacerations of the cervix with consequent inflammation, enlargement and increase of weight are other sequelae of childbirth that tend to cause prolapse.

(2.) Deranged Spinal Innervation. This interferes with the nerve supply of the ligaments and pelvic floor and causes their relaxation. By vasomotor disturbance congestion and increased weight of the uterus is caused. It thus has a two-fold influence in causing prolapse, and especially "settling" of the uterus. It operates also as a predisposing cause of subinvolution of the pelvic organs and structures.

(3.) Increased Weight of the Uterus. This may occur from tumors, chronic metritis or endometritis, chronic congestion or subinvolution.

(4). Anterior Traction on the Cervix. Adhesions may draw the cervix forward into the vaginal opening in the levator ani and abdominal pressure then forces the uterus downward. A cystocele or a rectocele may form after slight lacerations of the perineum and act in the same way.

(5). Increased Intra-abdominal Pressure. This is a factor which operates in conjunction with nearly all the other causes. Of itself it may occasionally cause an acute prolapse. It may be from violent and continued muscular efforts, straining at stools, coughing, sneezing, falls, abdominal tumors, or ascites. A sudden and violent increase of intra-abdominal pressure may cause acute prolapse in virgins.

(6). General Debility or Senile Changes. In cases of constitutional weakness, whether due to senility or other causes, the pelvic tissues participate. After the menopause there is atrophy of the supporting structures of the uterus, an absorption of fat usually, both of which tend to prolapse.

(7.) Posture. This is particularly a cause of "settling" of the uterus which so often occurs as a part of a general abdominal and pelvic ptosis. "Slumping," as has before been suggested eliminates the anterior lumbar curve and changes the plane of the pelvic inlet so that the intra-abdominal pressure and organs have more direct access to the pelvis.