The sound should really always be inserted after the cervix has been exposed through one or another valvular speculum, for thus only is possi bility of infection avoided. The wishes of the patients, however, and the necessity of avoiding repetition of measures previously used, require us to-day, in particular in the consulting room, to neglect such rules. The least that we can do is to carefully cleanse the vagina by means of injections. The use of the sound through the cylindrical speculum, as is recommended by Lair and even by Thomas, is not to be advocated for diagnostic purposes, and the results obtained are far below those from the other methods. The insertion, furthermore, is difficult, in that the room for manipulation is very limited, an objection, however, not applicable to Bandl's speculum.
The sound is used both for diagnostic and for therapeutic purposes. We will consider these in turn, and first in regard to diagnosis.
1. To ascertain the patency of the cervical canal.—This indication as regards the external os and cervical canal is a generally absolute one. Only exceptionally, in case of closure or narrowing at the level of the ex ternal os, can the finger or the speculum detect it. In other instances, and also to determine the degree of narrowing, the sound must make the diagnosis. An opinion may, of course, be formed as to the patency and width of the external os, from the changes in the uterus the result of stenosis, as also from the rational history in regard to dysmenorrhoea and sterility. Still the sound alone can give positive data. It is far more difficult to determine the size of the internal os. If it is not easy to make an exact statement in regard to the nature of an obstacle which arrests the sound to a depth of 1 inches, the more the expertness re quisite and the more necessary the repeated manipulations to differentiate between abnormalities in the direction of the canal and simple narrowing. Such is the reason why inexpert examiners meet so frequently with stenosia at the internal os.
2. Tc ascertain the depth of the uterine cavity.—By means of the sound and the touch W3 are able to determine not only the total length of the uterine cavity but also that of its individual segments. The vaginal portion of the cervix is measured by the finger, the cavity of the cervix is measured by the sound, and by subtracting the one from the other we obtain the depth of the supra-vaginal portion of the cervix. The total depth of the uterine cavity is obtained by deducting the measurement of the cervical cavity. Any conclusion as to the length of the uterus ob
tained by the bi -manual palpation is open to error, since the thickness of the walls of the uterus is an unknown quantity, and similarly the total meas urement obtained by the sound gives us no exact conclusion in regard to the total length of the uterus. The two means combined, the bi-manual and the sound, give us the most reliable results as to the thickness of the uterine walls, seeing that from the total length may be deducted the depth of the cavity obtainable by the sound.
3. For determining the width of the uterine cavity—that .is to say, its capacity.—The data here are less certain. They are obtained by a com parison of the obtained length with the greater or less movability of the sound in the uterine cavity, and the extent to which it may be moved sideways. These results are open to error, because on account of the curvature of the uterus the movements of the sound are limited. This remark is all the more applicable to cases in which the uterine cavity contains tumors.
4. For ascertaining the thickness of the walls of the uterus.—The thickness of the walls of the cervix may be readily determined, since they may be included between the finger in the vagina and the sound in the cervical canal. The thickness of the uterine walls are estimated by press ing the sound backwards and downwards against the finger in the vagina, or better still in the rectum, for the posterior wall, and the finger in the vagina, bladder, or through the abdomen, for the anterior wall.
5. For determining the contents of the uterine cavity, the presence of tumors, and for ascertaining the condition of its mucous membrane.—The sound only very exceptionally gives us reliable information in regard to these points, although it was formerly recommended by Biwisch and Scanzoni for the diagnosis of pregnancy. Mistakes are often made as the result of deviation of the canal of the uterus from its natural direction, from the catching of the point of the instrument in folds suggestive of tumors, and again from the insertion of the point into soft bodies in the cavity, such as blood clots. Even in case of pregnancy the sound may readily glide between the ovum and the uterine wall without injury to the former, and there are many instances on record of the use of the sound in ignorance of pregnancy without interfering with its course.