Besides these principal types of pelvic deformity, some others should be mentioned, which, as Depaul says, are only of importance so far as they are associated with the anomalies before-mentioned; these are abnor malities in the height, weight, or structure of the pelvis. Lenoir has de scribed a pelvis that was too high, and another that was too low, but De paul believes that he was in error when he endeavored to represent these as special types. This deformity in itself could hardly impede to any serious extent the progress of labor, and, if the diameters are normal, it is of no consequence. The same remark applies to variations in the thickness, resistance, weight, and structure of the ilia and sacrum; it is only when associated with other pathological conditions that they may under certain circumstances increase indirectly the complications already existing. There may be six instead of five sacral vertebrae, and the sym physis may be 2 or 2+ inches broad, or the coccyx may be anchylosed, all of which conditions may help to retard labor.
III. Faulty Inclination of the Pelvis.
The inclination of the pelvis may be increased or diminished, more often increased. Now, as Naegel6 and Greaser show, the head may be arrested at the level of thA symphysis, and thus it may be slow in engaging. If in this case the other conditions of parturition are normal, this slight difficulty is soon surmounted. But if, as usually happens, there exists at the same time a greater or less disproportion between the bead and the pelvis, the resistance offered by the anterior wall of the pelvis exerts a more unfavorable influence. In these cases Schultze and Naegel6 and Grenser advise that, whenever the head of the foetus impinges against the symphysis, at the brim of the pelvis, the woman should recline in such a way that the lumbar portion of her vertebral column is strongly flexed, —that is to say, that she should assume a semi-recumbent position. This
bent attitude assists the entrance of the head into the true pelvis.
The pelvis may be abnormally inclined forwards, backwards, or laterally. Forward inclination (anterior obliquity) consists in a more or less marked exaggeration of the normal inclination of the inferior strait, and is most common in rickets. In a case described by Naegeli., the inferior strait was directed straight backwards, the symphysis pubis and the upper half of the sacrum were horizontal, and the right ramus of the pubic arch was less inclined than the left, so that intercourse could only take place in a posture the reverse of the usual one. This did not cause contraction and the woman had seven children. Posterior obliquity is never as marked as anterior. In the most extreme degree of this deformity, the plane of the superior strait is horizontal, so that the axis of this plane is vertical and coincides with the axis of the body. Posterior obliquity may exist alone or be associated with other malformations. The vulva is often directed farther forward than normal, and the symphysis is more nearly vertical. The upper half of the sacrum is parallel with the axis of the body, and the lumbar curve is almost or quite absent. Finally, the tip of the coccyx in the erect posture is always either at a level with, or below the summit of the pubic arch, and the twelfth rib is generally nearer to the crest of the ilium than normally. In lateral inclination the pelvis is more or less inclined to the right or left. This inclination is mostly observed in rachitic pelves, and in patients with shortening, or atrophy of one of the lower limbs, or dislocation of the hip. The most striking peculiarity is the difference in level of corresponding parts of the pelvis. This abnormality is more frequently associated with other more important deformities than are the two preceding forms.