A System of Midwifery

by Edward Rigby

Symptoms of deformed pelvis. Among the external appearances which would lead us to suspect a deformed pelvis, are “the lower jaw projecting beyond the upper; the chin very prominent; the teeth grooved transversely; unhealthy appearance; pale ashy colour of the face; diminutive statue; unsteady gait; when the woman walks the chest is held back, the abdomen projects, and the arms hang behind; there is deformity of the spine and breast, one hip higher than the other, the joints of the hands and feet are remarkably thick; curvature of the extremities, especially the inferior, even without distortion of the spine is a very important sign; wherever the lower extremities are curved, the pelvis is mostly deformed: it is well to ascertain also if, when a child, it was a long time before she could walk alone; whether she had any fall on the sacrum; whether as a girl she was made to carry heavy weights, or to work in manufactories.” (Naegelé’s Lehrbuch. § 444.)

Funnel-shaped pelvis. Besides the above-mentioned species of pelvic deformity, others are occasionally met with, the origin of which is but little understood. The funnel-shaped pelvis is of this character, where the brim is perfectly well formed, but where it gradually contracts towards the inferior aperture. There are no evidences of its having been produced by any disease; nor in fact can we assign any satisfactory cause for this peculiar configuration: it appears to have been a congenital formation.

Obliquely distorted pelvis. A still more remarkable species of pelvic deformity is the pelvis obliqué ovata, which, of late years, has been pointed out by Professor Naegelé. In this case the pelvis appears awry, the symphysis pubis being pushed over to one side; and the sacrum to the other; one side of the pelvis is more or less flattened, the other bulges out, so that one oblique diameter is shorter, the other longer than natural; and this applies not only to the brim, but to the cavity and outlet of the pelvis. In most cases the sacro-iliac symphysis on that side which is flattened, and to which the sacrum is inclined, is completely anchylosed, not a trace of the division between the ilium and sacrum to be detected, the two bones being completely united into one. In many, the sacrum on this side is smaller than on the other, as if a portion of it had been removed by absorption during the process of anchylosis, or at least not properly developed. When we consider the form of the pelvis, and the appearances which the sacro-iliac symphysis and the sacrum present, we are almost led to conclude that ulcerative absorption must at one time have existed between the sacrum and ilium at this point, probably at an earlier period, by which means more or less bone had been destroyed before the termination of the disease in anchylosis; indeed, we can to a certain extent imitate this peculiar species of pelvic deformity by sawing off the surfaces of the sacrum and ilium which had formed the symphysis, and then putting the bones together again. Still, however, in the various cases which have been collected by Professor Naegelé, no proofs could be obtained of disease having existed in the pelvis during early life.

“In none of the cases, the particulars of which have come to my knowledge, has there been any trace of rachitis; nor have any of the symptoms, appearances, and morbid changes been observed which characterize mollities ossium coming on after puberty. None of these cases have been traced to the effects of external violence, as falls, blows, &c.; nor has there been any complaint of pain in the region of the pelvis, inferior extremities, &c.” (Das Schräg Verengte Becken, p. 12.) “With respect to the strength, colour, structure, &c. of the bones of this species of deformed pelvis, no difference could be observed between them and the bones of young and perfectly healthy subjects; not a trace either in form or other respects could be detected of those changes which usually result from rachitis or mollities ossium; and but for this distortion and some other slight irregularities, which required close inspection to detect, these pelves would have been looked upon as well-shaped, and of sufficient capacity.” (Naegelé, op. cit. p. 11.) In some specimens no trace of anchylosis at the sacro-iliac symphysis has been observed; but whether this was the case throughout the union of the two bones we cannot say. Professor Naegelé is inclined to look upon them as modifications of the pelvis obliqué ovata, and certainly in the majority of known cases anchylosis has been found present.

It is scarcely necessary to do more than enumerate other varieties in the form of the pelvis, which are occasionally met with: it is sometimes round, the transverse and antero-posterior diameters being of the same length; in other cases it possesses many of the characters which distinguish the male pelvis, being more or less triangular, deep, and with a contracted angular pubic arch.

Exostosis. Lastly, the pelvis may be perfectly well formed, but the passage through it more or less interrupted by the exostosis: this is, perhaps, the rarest species of dystocia pelvica. It may arise from wounds of the periosteum, from fracture of the bones, callus, &c. and may vary in size from a small protuberance to a large mass, which completely fills up the pelvis.

Diagnosis of contracted pelvis. The difficulty of detecting an abnormal configuration of the pelvis, will depend, in great measure, upon its extent: where it is but slight, it may easily be passed over unobserved by a young practitioner, although it may, nevertheless, be quite sufficient to render labour both difficult and dangerous. In the ordinary form of contracted pelvis, where the antero-posterior diameter is shorter than natural, the being able to reach the projecting promontory of the sacrum with the finger is of itself a sufficient evidence: but the converse of this is not true, for we frequently meet with cases of contracted pelvis, without being able to reach the promontory. The numerous instruments which have been invented at different times for measuring the pelvis are of such doubtful accuracy, as to be nearly useless; the experienced finger is the best pelvimeter; and the power of correctly estimating the dimensions of the pelvis during examination, can only be acquired by constant practice, based on a thorough knowledge of them in the healthy pelvis.

The manner in which labour commences is frequently sufficient to make us suspect the presence of a contracted pelvis. Besides, the general appearance of the patient, we frequently find that the uterine contractions are very irregular; that they have but little effect in dilating the os uteri; the head does not descend against it, but remains high up; it shows no disposition to enter the pelvic cavity, and rests upon the symphysis pubis, against which it presses very forcibly, being pushed forwards by the promontory of the sacrum. It is probably from this circumstance that the os uteri, more especially its anterior lip, shows so little disposition to dilate in these cases, for the lower portion of the uterus being jammed between the head and symphysis pubis in front, and promontory behind, the contractions of the longitudinal fibres can have little effect upon the os uteri. Hence we find, that in cases of diminished antero-posterior diameter requiring perforation, and where the os uteri in spite of violent pains, bleeding, &c. has refused to dilate beyond a certain point, on lessening the head, and thus removing its pressure from the symphysis pubis, it has quickly attained its full degree of dilatation.

Where the pains have been active, and a portion of the head has forced itself through the brim, and now projects to a certain extent into the cavity of the pelvis, it will be still more difficult to reach the promontory before delivery; and if, as is frequently the case, the sacrum is bent strongly backwards, so as to render the cavity and outlet very spacious, the real cause of impediment to the progress of labour may be entirely overlooked. It is here that the position of the head upon the symphysis pubis will prove a valuable means of diagnosis. The straightness of the sacrum will also be a guide in other cases.