Not infrequently a congenital stenosis is confined to the os externum; it can scarcely be discovered on examination by touch, and by the aid ef the speculum is recognized as a very small round opening from which, as a rule, a drop of mucus is seen to protrude. The ring formed by the external os is round, not soft and flexible, but generally strongly resistant and of a whitish appearance; desquamation of the epithelium in the sur rounding parts also occurs. The ordinary uterine sound can not be in troduced into the opening; it glides over it, since the button is too large. Only a probe of smaller calibre, like those used in surgery, can pass the stenosed place. The cervical canal behind it may be narrowed, or nor mal, or, on the contrary, may be more or less widened; the cavity is then filled with mucus, or, as I once observed, with large masses of pus. The uterine mucous membrane is frequently in a catarrhal condition, however. I have rarely found in nulliparm those changes in the body of the uterus 'which are to be explained as chronic metritis. The smallness of the uterine body also, that not infrequently is combined with stenosis of the entire cervical canal, is observed less frequently in partial stenosis of the os externum. The body of the uterus is generally quite normally developed. The vaginal portion may be normal; sometimes it is some what elongated or tapering, so that the transitions to the normal vaginal portion, us well as to the conically elongated vaginal portion, occurs in a large proportion of cases.
There has been much dispute about the significance of this stenosis, while some do not attach any importance to it, intuienuch as the spermatozoa can enter even through the smallest opening; others again consider it a great obstacle to conception. This divergence of opinions that are rather sharply opposed to one another, is largely founded upon the various views held in regard to the mechanical obstacle to conception. The latter exists according to the opinion of some only where the meeting of sperma and ovum is rendered entirely impossible, or occurs very rarely. Absolute and relative causes of sterility are not exactly distinguished by them. Yet such an obstacle must exist when the meeting of the two forms is not absolutely prevented, but merely rendered more difficult. The nar rowing of the external os undoubtedly offers an obstruction of this kind. Let us represent to ourselves thc conditions at the os externum: the sper matozoa that are deposited in the wide hollow space of the vagina, having no instinct to lead them to the os, will meet the latter only by chalice. If the diameter of the os is diminished only by one half, the chances of meeting must be only one third as great. But as a rule, this amounts to little with the usual large number of spermatozoa, but it must at once become marked when there are complications which here are frequently present, and may in various ways increase the obstruction.
The relation of the mechanical cause of sterility to the frequency of conception, might be elucidated by the following examples: Suppose there are ten women, perfectly healthy, with normal os uteri; they all conceive. Now let us take ten other women in whom a narrowed os uteri can be demonstrated; of these eight conceive, while two remain sterile. Why the last two did not conceive while the first eight did, is the next question. Perhaps the secondary appearances (cervical catarrh, etc.) were so strongly pronounced in these very two cases, that the sperma which passes the narrow os is yet unable to advance to the ovum, while in the other cases no such consecutive obstruction existed. But at any
rate the fact that in the first-named cases pregnancy occurred, does not justify us in saying that the stenosis of the os externum did not prevent conception in the last two cases. Another example: Here are two women; the one has a normal os and conceives five months after mar riage. The other, who has a narrow orifice, but no other genital defects, conceives only after five years have elapsed. Should we now conclude that, because conception yet occurred, the stenosis could not have been the factor which prevented conception for so many years? The solution of the problem might perhaps be as follows: Suppose the sexual power of the two husbands to be equal and not very considerable; then in the first woman the few spermatozoa might succeed in entering through the wide es, and through the cervical canal, which is not plugged, int,o the uterine cavity. It is different with the other woman. Could we not believe that, since cohabitation is frequently performed, tho amount of sperma that enters the vagina is also scanty, and the few spermatozoa either do not reach the external os at all, or perish in the cervical mucus; while after a separation of long duration, or after a longer abstinence dictated by other reasons, a greater amount of sperms is brought in contact with the narrow os uteri, and of this large number of spermatozoa, some may succeed in penetrating through the cervical canal ? Consecutive disturb ances or contemporary complications dependent or not dependent upon one another may, in combination with abnormalities in the generative power of the male, render it difficult to overcome the mechanical obstacles, while the isolated appearance of an obstacle together, with full potency of the male, may sometimes promptly overcome the difficulty. The same thing is true of other mechanical obstacles, especially flexions of the uterus The effect of a stenosis. in rendering conception difficult may also be proved by the contrary. Nobody denies that women who have been preg nant. all other conditions being normal, conceive much more easily than those in whom there has been no previous childbirth. It can scarcely be doubted that the width of the external os is the favorable factor with the first. Bat when a width that excels the lumen of the os externum of nulliparse can bring about a plus of fertility, why should not a too great narrowness be able to have a minus as its consequence? But the obstruct ing effect of a stenosis becomes very strikingly evident in the cases in which, after prolonged duration of sterility, conception finally ensues; the pregnancies then generally follow in regular, sometimes even abnormal frequency—a sign that the former narrowness had a disturbing effect upon the process of generation. Some indeed do not deny the unfavorable effect of a stenosis, but ascribe the obstructed conception to the conse quences of the stenosis. This is only partly true, for the promptness with which, conception ensues after removal of the obstacle, at a time at which the consequences can not have been nearly removed also, speaks for the unfavorable effect of the stenosis itself. Cases where, after sterility had lasted not for a short time, but for years, conception occurred soon after retnoval of the stenosis, are not rare, and would also speak in favor of the importance of this anomaly of the os uteri. But certainly the stenosis is not always the only cause of the sterility, but probably also the consequent plugging of the cervical cavity with mucus, which with its tough con sistency often expands the canal into a spacious oval cavity and will scarcely allow the sperm& to pass.