A System of Midwifery

by Edward Rigby

In that form of the pelvis which has been called the funnel-shaped pelvis, and where the brim and upper portion of the cavity are of the natural dimensions, but where it gradually diminishes towards the outlet, the appearances are frequently very deceptive, the head advances without impediment, and descends as far as the inferior aperture, with every promise of speedy delivery; but here its progress is arrested, and even in the very last stage may require perforation.

It occasionally happens, also, where the deformity is very considerable, that the promonotory projects to such an extent as to be even capable of being mistaken for the head itself; and cases have actually occurred where, under this impression, the bone has been perforated instead of the child’s head. So gross an error as this may easily be avoided by care in making the examination; by ascertaining that the projecting mass is immoveable; that the patient is sensible to the pressure of our finger; and that the promontory can be traced to be continuous with the adjacent parts of the pelvis.

The effects which may result from labour protracted by pelvic deformity are very various, both as regards the mother and her child. The most common form of injury which is produced by this cause, is the contusion and consequent inflammation and sloughing of the soft tissues which line the pelvis from the long continued pressure of the head against the symphysis pubis in front, and against the promontory of the sacrum behind. Not only may sloughing of the vagina and lower part of the uterus be the result, but the mischief may extend through the posterior wall of the bladder, and thus render the patient incapable of retaining her urine, and an object of great, and, generally speaking, incurable suffering.

The danger from rupture of the uterus will chiefly depend on the degree of pressure with which the uterine contractions force the head against the brim. Where the pains are violent, and yet insufficient to overcome the obstacle which the contracted pelvis presents to the advance of the head, there is not safety for a minute, and perforation must be immediately had recourse to. Where the edge of the promontory is very projecting and sharp, the structure of the uterus may be seriously injured by the pressure and contusion. In some cases it has evidently been the cause of ruptures, the fibres having given way first at this spot.

The constant severe pressure upon the head will be not less injurious to the child’s life; it must inevitably produce a considerable impediment to the cerebral circulation; and where the liquor amnii has escaped, the pressure of the uterus upon the body of the child will scarcely be less prejudicial. The cranial bones frequently become remarkably distorted, so that after a difficult labour a deep furrow is found on that part of the head which corresponded to the projecting promontory.

Fracture of the parietal bone may even be produced, a fact of which practitioners, till lately, have not been sufficiently aware; and cases have occurred where children have been born dead, with the head greatly distorted, and one of the bones fractured, from which circumstances the mothers have been suspected of infanticide. Dr. Michaelis, of Kiel, has lately reported an interesting case of this kind, where the fracture seems to have resulted from the great immobility of the coccyx. The head was much disfigured, and on examining it the frontal bones were uninjured, but so flattened that the frontal and parietal portions of the sagittal suture lay nearly in the same place; the fontanelle and anterior two-thirds of the sagittal suture projected high up, and the sagittal borders of the parietal bones were firm and well formed. In the posterior third of the sagittal suture, where the parietal bones were firm and well formed, and the suture only two lines in width, were seen small livid portions of the longitudinal sinus forced between the bones. The occipital bone was flattened and forced deep under the parietal bones, but not otherwise injured. The right parietal bone, which during birth had been turned towards the promontory of the sacrum, was covered anteriorly and superiorly with effused blood, and on removing the periosteum, was found fractured in five places. (Neue Zeitschrift für Geburtskunde, vol. iv. part 3. 1836.[124])

Where the action of the uterus is not very violent, and the bones yielding, the head gradually adapts itself to the form of the passage without destroying the fœtus; it elongates itself more and more until it is enabled to pass, so that after a tedious labour of this sort, we sometimes find the configuration of the head remarkably altered. Baudelocque, has mentioned a case recorded by Solayres de Renhac, where the head was so elongated that the long diameter measured eight inches all but two lines, the transverse being only two inches and five or six lines.

Treatment. Where the pelvic deformity is very considerable, there can be little difficulty in deciding upon the line of conduct to be adopted. It is in those cases where the obstruction is but slight that the indications for treatment are less distinctly marked: nor must we be satisfied with merely ascertaining the relative proportions of the head and pelvis; for the hardness or softness of the cranial bones, the disposition which they manifest to yield to the pressure of the uterus and surrounding parts, the state of the cranial integuments, and though last not least, of the soft tissues which line the pelvis, must all be carefully ascertained before a correct opinion as to the precise mode of treatment can be formed. Nor, if the woman has already had children, can we altogether be guided by the history of her previous labours; for where the above-mentioned circumstances have been favourable, a slight diminution of the pelvis will scarcely be attended with any perceptible delay or increase of difficulty beyond the natural degree; whereas, if the head happens this time to be a little larger, its bones more ossified, the fontanelles smaller, the scalp and soft linings of the pelvis more swollen, &c. a serious obstruction to the progress of labour will be the result. Thus it is that we not unfrequently meet with patients in whom the first labour has been tolerably easy, the second has been attended with much difficulty and required the forceps, in the third, the difficulty was so much increased as to require perforation, and the fourth where the labour was, like the first, perfectly easy and natural.

It is impossible for the head to remain long in the pelvis (except under unusually favourable circumstances) without more or less obstruction to the circulation, both in the scalp itself and in the surrounding soft tissues. The necessary consequence of this is swelling, by which the head increases while the passage diminishes in size; and this must still be more remarkably the case where the pelvis is at all contracted. It is in these cases that we frequently see such relief produced by venesection; and it is also as a topical depletion to the overloaded vessels, that we can explain why a free secretion of mucus is so favourable a symptom.[125]

Prognosis. Where the pains are moderate and equable, the os uteri nearly or quite dilated, the head not large, its bones yielding and overlapping at the sutures; where the greater portion of it has evidently passed through the brim, and, although slowly, advances perceptibly with the pains; where the passages are cool and moist, the pulse good, and the patient not exhausted, we may safely wait awhile and trust to the efforts of nature. On the other hand, where the pains are violent, the os uteri thin and undilatable, the head forced forwards upon the symphysis pubis by the projecting serum, if the greater part of its bulk has not yet passed the brim, if the soft parts are much swelled, the vagina hot and dry, the pulse has become irritable, the abdomen tender, the patient exhausted and much depressed both in mind and body, the powers of nature are evidently incompetent to the struggle, and require the assistance of art.