THERE is no subject in the whole field of obstetrics which receives so little attention in our Society discussions as that of pelvic deformities. To the relative infrequency of these abnormalities as compared with other obstetrical may be attributed the neglect which this subject receives. Though seldom encountered in practice, we are not justified in totally neglecting this important branch of obstetrical study.
The writer has endeavored to ascertain the frequency of pelvic deformity in lying in institutions in this country, wherever statistics have been published, and as a result interesting information has been obtained.
In a series 2127 cases of labor in the out-patient department of the Boston Lying-in Hospital, Dr. Edward Reynolds [Transactions, Am. Gyn. Sec., 1890.] found 22 instances of pelvic deformity, and in 100 cases of confinement in the wards of the same institution five cases were observed. Dr. James W. McLane reports 10 cases in the first 100 cases of confinement in the Sloane Maternity.
In 3225 cases of confinement attended by students at the lying-in hospital in New York City, during the first three years of its existence, in only one instance was reduction in size of the foetus demanded on account of a contracted pelvis. IOn another, premature labor was induced on account of a contraction of the pelvis in all its diameters; in not a single instance did the absolute indication for Caesarean section exist from any cause. Pelvimetry is systematically employed by the students of this school.
This is a remarkable record, and shows a much smaller percentage of cases of pelvic deformity than is generally supposed to be the case. Dr. Edgar states. with regard to the case (1154) confined during the first two years in the their lying in hospital, in not a single instance did a markedly contracted to the minor de it is not assuming too much to suppose that some of the forcep operations and cases of version were performed on account of the small size of the pelvis.
In 250 cases of labor in private and consulting practice of which the writer has record, there were three cases of contracted pelvis; one simple flat pelvis and two symmetrically small pelvis. The latter-the justo-minor pelvis-is the variety most frequently seen in women of American birth.
Among the 100 cases in the wards of the Boston Hospital, referred to in Reynold’s tables, there were 57 native women who presented one case of pelvic deformity, and that of a typical justo-minor type, the percentage of 1.75 per cent. being almost identical with that obtained among native women from the out- patient department of the same institution and the obstetrical department of the Boston Dispensary, which was 1,6 per cent. In contrast to this the remaining 43 foreign women yielded four examples of the simple flattened pelvis (9,4 per cent) and no justo-minor pelvis.
Among Reynold’s 2127 women of all classes, 10.3 per cent. possessed contracted pelvis of one variety or another. Aboard, the average is about the same. Winckel says: [Text-Book of Midwifery, p. 451.] “After all pregnant and parturient women were carefully examined as regards their pelvic relations, there were found, among 1199 births, 115 women with contracted pelvis (9 1/2 per cent), a figure which coincides exactly with those obtained of late years in the Werzburg clinic (8.10 per cent), and approaches closely to those obtained by Michaelis and Litzmann.
The first regular pelvic measurements were made in 1840-1847 by Michaelis, of Kiel, who found in 1000 parturients 131 cases of narrow pelvis (10.3 per cent).
Litzmann (1848-1886) found in 1000 parturients 149 (10.4 per cent.). Subsequent observers up to Winckel’s time found a much smaller number of cases, but the difference is undoubtedly due to the fact that more than half the cases of slight narrowing were not recognized because they produced no difficulty in labor. Winckel concludes that “we shall not go too far in making the statement that contraction of the pelvis is present in 10 to 15 per cent. of all parturient women, but that usually only about 5 per cent. are recognized even in clinical institutions on account of the effects upon labor.”
This would seem to be about the frequency in this country if we include all classes. Women of American birth are undoubtedly less frequently the subjects of pelvic narrowing than those of foreign birth. Furthermore, it may safely be concluded than an American birth decreases the amount of pelvic deformity among the children of foreign parents.
The predominance of the rachitic types of deformed pelvis, characterized by irregularities in shape of the whole pelvis and especially by flattening of the inlet by undue projection of the promontory among women of the lower classes born aboard, is probably due to insufficient nourishment and hard work before or during puberty.
The symmetrically small pelvis, due to simple arrest of development at puberty (a partial persistence of the infantile type), is the variety generally met with in women of American birth and lineage, and is due, as might be expected, to the peculiar character had habits of American women and nineteenth- century civilization.
In the practice of midwifery, the following questions are now and then presented for solution:.
1. Is there any external evidence or anything in the progress of a labor in its early stage which will enable one to suspect the presence of a pelvic deformity?.
2. What constitutes pelvic narrowing, and how are we to determine that such a condition really exists as well as the variety and degree of the deformity?.
3. Is it possible to ascertain, before labor sets in, the relation of the presenting part of the child to the narrowest diameter of the pelvic through which it must pass to accomplish delivery?.
4. Can we define, with any degree of certainty, the limitations of the different operative procedures by an approximate of the extent of the narrowing?.
I shall endeavor to answer these questions seriatim:
1. With regard to the significance of physical peculiarities in pointing out the possible existence of pelvic deformity.
While narrow straight hops and short limbs may not prove to be indicative of diminished transverse and oblique diameters, the fact that such peculiarities of shape coexist should not be overlooked. As Spielgelberg says, [Text-Book of Midwifery, vol. xi., p. 30.] when he emphasizes the importance of making pelvic measurements” “Still, the other circumstances deserve that full weight be given them, and even if they never afford more than certain points d’ appui, suggestive, to a certain extent, of the direction in which measurements should especially be made, they nevertheless assist in deciding the best treatment for special cases”.
An unusually short person, or a tall, slender woman, with very narrow hips, or lameness due to diminished length of one leg; women with abnormal curvature of the spine, or undue hollowness of the back, which is usually the external evidence and accompaniment of excessive inclination of the pelvis; none of these peculiarities should escape the eye of the careful obstetrician. They may mean nothing, or they may be suggestive of more serious defects, the detection of which, by more extended observation, will enable one to act intelligently at the time of labor, and thus possibly save a life which, without such preliminary knowledge, might be sacrificed.
The life-history of a woman with a spinal curvature or other evidences of defective development should be carefully scrutinized to ascertain if rachitis existed during childhood.
If physical peculiarities do not exist, or have been overlooked, the conditions revealed by an examination at the onset of labor may be of great value in pointing out the presence of contraction.
Failure to reach the presenting part, the non-descent of the head and the resulting protrusion of the elongated bag of waters under the influence of the uterine contractions, and the imperfect adaptation of the head to the lower uterine segment, are conditions so suggestive of either an abnormal presentation or a pelvic contraction that a discriminating diagnosis should at once be made.
The occurrence of constriction or retraction rings after rupture of the membranes, without advance of the presenting part, is evidence of obstruction, and the continuance of natural labor under such circumstance only adds to the difficulties which already surround the case.
The symmetrically small pelvic (the justo-minor pelvis) has scarcely any external signs by which we may detect it except, perhaps, narrowness of the hips in a woman otherwise of normal proportions, though it would be more natural to suspect its existence in a very short woman. Rachitis, which causes the flat pelvis, or the generally contracted that pelvis, does not always produce pelvic deformity in proportion to the intensity of disease apparent in other parts of the skeleton, and sometimes it produces no pelvic deformity whatever.
A woman with a decided spinal curvature may have a perfectly normal or even a large pelvic, the location of the deviation of the bones of more importance than the degree of it. Again, a woman may have a slight degree of pelvic deformity and yet be delivered spontaneously and successfully, especially in a first labor, the ability or failure to do so depending upon the relation which the child bears to the contracted portion of the pelvis through which it must pass in order to be delivered.
2. What constitutes pelvic narrowing, and how are we to determine that such a condition exists, as well as the variety and degree of the deformity?.
One of the most important advance in the teaching of practical midwifery is in the direction of systematic examination of the pelvis of pregnant women by means of the pelvimeter, the tape, and, most important of all, by the hand of the examiner within the pelvic cavity.
Every physician who does much obstetrical work should familiarize himself, in the first place, with the shape of the normal pelvis by examining the pelvic cavity carefully with regard to its sacral curve, depth of the lateral walls and of the symphysis pubis, the inclination of the pelvis and the degree of projection of the sacral promontory.
External measurements are not of great value, because we cannot estimate exactly the thickness of the intervening bones or of the soft parts. Still, conclusions can be formed which will enable one to determine approximately the development of the innominate bones, and the width of the transverse diameter of the pelvic, inlet. The same remarks applies with equal propriety to the external measurements of the conjugate at the brim, which is taken from the spinous process of the last lumbar vertebra, to the upper border of the symphysis, and should measure not less than 17.5 cm. )or seven inches) in the living subject.
The internal method with the left hand in the vagina, is the method which gives most accurate information, and the greater the contraction the more reliable is the result. This method is practiced as follows: With the fore- and middle fingers of the left hand in the vagina the promontory of the sacrum is touched. The keeping the middle finger on the promontory, press the side of the forefinger against the lower edge of the symphysis. The forefinger-nail of the right hand is then placed where the examining hand is touching the symphysis.
Remove the two hands together without separating them, so that the finger-nail may accurately mark where the hand was in contact with the symphysis. An assistant then with a tape measure or rule, measures then distance between the tip of the middle finger and the place where the side of the hand touched the lower edge of the symphysis. The distance is the diagonal conjugate and it usually measures half an inch more than the true conjugate which, as is well known, is four inches.
Now, one would naturally suppose that a contraction of the conjugate below four inches must exist to constitute pelvic deformity. As a matter of fact, however, the conjugate may measure four inches, and if the other diameters are reduced so that the inlet is nearly round, as in the generally small pelvic (the justo-minor type), an obstacle to the progress of labor may be encountered at the superior strait.
On the other hand, lessening of the conjugate at the brim to three and three-quarter inches or even to three and one-half inches (Winckel) as in the simple flat pelvis (the other diameters being normal) no obstacle to deliver will occur, and the deformity may remain unsuspected, although the mechanism of labor is generally altered. it is only in unfavorable complications such as would occur with a large foetus or an abnormal presentation, that serious disturbance of labor is observed.
In consequence of these peculiarities, some authors, and especially those who obtain the lowest percentages, recognize as abnormal only those cases in which arrest occurred in pelvis where contractions were three and one-half inches or less. While those who find deformity most frequent admit to their tables only those pelvis whose conjugates are diminished by only one- fifth of an inch. For practical purposes we may say that dangerous contractions exist in the generally small pelvis, though the conjugate measures full four inches, and in the flattened pelvis with ample transverse space when the conjugate is reduced to three and one-half inches.
The difficulties met with in the delivery of a child through a conjugate of four inches in the symmetrically small pelvis may be explained by the fact that the transverse diameter in a pelvis of this variety, is no longer, and may not be so long as the antero-posterior; hence diminution of the oblique diameter and greater difficulty in effecting an entrance of the head than would be the case with even a shorter conjugate and more transverse space.
Besides in these cases the obstruction to labor is not limited to the superior strait, but continues through the whole pelvis. The mechanism is that of early and complete flexion, with occasionally a delay in rotation from decreased inclination of the inferior pelvic planes-and the increase in the length of the pelvic axis.
These remarks apply with almost equal force to the generally contracted flat pelvis as regards the obstacle to labor at the superior strait, since internal palpation shows the transverse space at the brim to be diminished almost as much as the conjugate. A generally contracted flat pelvis with an antero- posterior diameter of four inches, is therefore capable of giving rise to as much difficulty as the symmetrically small pelvis of the same conjugate diameter. Normal labor is possible in either of these varieties of pelvis, though usually assistance by means of forceps is required.
The characteristics of the simple flat pelvis is the shortened conjugate diameter, extreme contraction being uncommon, the length of the conjugate rarely falling below three inches. This diameter may not fall below three and three- quarter inches, and when diminished to this slight degree only, labor many terminate without instrumental assistance, though version and forceps are alternative operations which often come into competition with each other.
3. The duty of the obstetrician when confronted by a contracted pelvis is to form as accurate on idea as possible of the type and measurements of deformity he has to deal with, and at the same time determine approximately the size, shape, and consistence of the infantile head. If the gestation has advanced to full term, we know what the average measurements of the foetal head are at this time. But it is a matter of great importance to know in the particular case in hand what the relation of the head is to the pelvis through which it must pass.
Tables have been complied which give the approximate weight of the child at different periods from the thirty-second to the fortieth week, with the appropriate biparietal diameter of the foetal head at the corresponding periods, as well as the diminished conjugate diameters to which the foetus may be expected to adapt itself at these times.
But for practical purposes such tables are useless. No one would ever be able to recall at the critical moment the information he desired, and if he could recall it the chances are that the knowledge would not be useful in solving the problem. We may determine the relative measurements of the pelvic canal at tits constricted portion, which is usually the conjugate of the superior strait, by a very simple procedure. This manoeuvre may be resorted to during gestation, or when labor has begun at full term.
To secure this information, map out by external palpation through the abdominal walls, the body of the child as accurately as possible. In the hypogastric region we search for the neck of the child, which is determined by the depression between the dorsal surface of the trunk and the region of the occiput. Then the head of the child is mapped out by bimanual examination, and to prove he corrections of the diagnosis, the head is made to descent slightly upon the examining finger within. If an assistance of intelligence is at hand, the external manipulation may be conducted by him. The head of the child is then made to descend by simultaneous pressure upon the breech and occiput.
The hand within the vagina then ascertains whether the head really descends, whether it passes the promontory, or whether rotation occurs. Where series obstacles are present it is easy to prove that the head remains with the greatest diameter above the pelvic brim, and even bulges out the region above the symphysis. Such a determination of the relation of the head of the pelvis is of decided importance in setting the time for the induction of premature labor, in serious cases of pelvic deformity, especially when we are in doubt as to the period of pregnancy. Labor can be brought on when the head can be pressed into the pelvis no further than the vertex, and delivery will be accomplished to soon if the head is pressed into the pelvis down to, or slightly below the parietal protuberances.
In case of an obstacle to labor at the superior strait, the gestation having advanced to full term, this method of determining the adaptability of the foetal head to the pelvic inlet may be of great service and enable one to choose between two or more competitive procedures. No great force is necessary to secure adaptation, and it need not be continued more than moment or two. The lower uterine segment offers no obstacle to the descent of the head. The only difficulty to be anticipated would occur in case of a woman with fat abdominal walls or with great hyperaesthesia of the uterus. Anaesthesia might be necessary. This method can never supersede internal measurements by palpation, but may be employed in conjunction with them and it has the additional merit of affording a very accurate idea of the relation of the foetal head to the pelvic inlet.
We will now proceed to define the limitations of the different procedures called for in pelvic narrowing, bases upon comparative degrees of deformity expressed in inches at the conjugate of the superior strait.
It is obviously impossible to construct rigid absolute rules for the guidance of the surgeon in cases of this kind. Other factors besides that of pelvic contraction have to be taken into consideration, and herein the personal equation, i.e., the skill and experience of the operator are of great value in deciding in favor of one procedure or another.
The variety of the deformity, as well as the degree of contraction in both transverse and conjugate diameters, the depth of the symphysis and angle of inclination, the size of the foetal head, the condition of the child, and duration of labor are all factors of such great importance that neither one can be neglected in the estimate of the procedure which it is desirable to adopt to effect delivery. In a Society discussion, or in a formal essay, we can venture to split hairs, and declare that this or that operation is the suitable one in a certain variety of deformity, with contraction not exceeding a certain degree. But at the beside all this is changed. It is results that we are anxious to obtain-to save both lives, if possible, which, considering the means at our command at the present day, we are not to be excused if we fail in securing.
The only hope we have of ever being able to accomplish such results is to study our cases in advance. Since it is practically impossible for two men to agree regarding the exact length of the true conjugate, how are we to be guided by a difference of 1/4 of an inch, as to whether we shall elect forceps, version, craniotomy, symphyseotomy, or the Caesarean section. These are the most difficult problems that can ever be placed before any man, and only the highest judgment, based on the most through examination, under the most favorable conditions, can hope for a satisfactory answer to these questions.
4. Can we define, with any degree of certainty, the limitations of the different operations procedures by an approximate estimate of the external of the narrowing?.
Under this head we have, as elective operations, forceps, version, symphyseotomy, craniotomy, and celiotomy of Caesarean section. The answer to the above questions may be stated in five propositions.
1. These cases in which the deformity is limited to a shortening of the conjugate at the brim, and does not exceed 3 1/2 inches. In simple flat pelvis contraction of the conjugate to this extent may terminate in normal labor, or forceps or version may be the operations of election. When all the diameters are reduced to the length of the conjugate, as in the justo-minor pelvis, four inches at the latter point may give rise to considerable delay in delivery and require forceps, though a natural birth of a living child at term is probable. A conjugate of four inches in the generally contracted flat pelvis may also cause difficulty in the birth and require forceps or version.