A NEW METHOD FOR ESTIMATING THE RELATIVE SIZES OF THE FŒTAL HEAD AND MATERNAL PELVIS *

SOME little time ago I came across, in the report of a clinical lecture by Barbour, the remark : “ The f e t a l head is the best pelvimeter.” The aphorism, so true in its completeness and so complete in its truthfulness, a characteristic by no means common to such sayings, delighted me so much that I determined to make it the text of my few remarks. I need not, in an assembly of obstetricians and gynaecologists, take up time in enlarging upon the fact that neither by manual examination even the most careful nor by yelvimeters even the most modern can the exact degree of pelvic deformity be appreciated. If anybody doubts that truth he has only to see, as I have done, a few cases of pelvic deformity i n which the pelvis was measured during life and after death in the post-mortem room to be convinced of the fact. I have seen a difference of a $-+in. in the conjugate Vera between the tw-o measurements, and that not only in cases of my own but in those in the hands of others of much longer experience. Then again attempts a t estimating the size of the fcetal head in utero must, I think, be admitted by all t o be most disappointing. The fact that the abdominal and uterine walls are often so resistant that we cannot be sure of the exact spot on the surface of the skull on which we are placing the ends of the calipers, and the fact that seldom is it possible to take a transverse measurement of the head are some of the more important difficulties in the way of this method of examination. With sorrow then we must admit that by the present method at our disposal we can obtain measurements of the maternal pelvis and fetal head only approximately correct. I n recent years, and especially since Miiller’s writings on the subject, more attention has been given to the relative sizes of head and pelvis. I say in recent times because Rigby, whose writings always appear to me amongst the most valuable in obstetric literature,