PELVIC DEFOP.MITIES AND OBSTRUCTIONS.
—Defbrmilies of the pelvis, properly so called, are all such departures from the adult "stan dard," in size, build, and conformation as are sufficiently marked to influence child bearing.
They have been variously arranged, but seem to fall best under two heads : viz.— 1. Normal irregularilies—including all those which present the shape and proportions pro per to the healthy pelvis at some period of its development ; and,-2. Distortions,—including all such peculiar alterations of shape and size as are consequent upon disease or injury.
1. Normal irregularities may be subdivided into,—Equable deviations, in which the general form and appearance are similar, and the dia meters proportionate to those of the "standard" pelvis ; and,—Irregularities from imperfect de velownent, in which the shape deviates frotn, and the diameters are not in proportion to, those of the " standard." Equable deviations.—" Pelvis equabiliter just° major."— The irregularity in this pelvis con sists in all the diameters being in excess. It is not uncommon. Burns records one ex ample. Dr. Murphy has another in his pos session, and there is in the Museum of King's College a third, the brim of which measures 6 inches transversely, by 5 inches antero posteriorly. The largest hitherto recorded is one by Giles de la Tournette, who gives in.
The distance between iliac crests - - 124 „ Antero-posterior diam. of brim „ Transverse diam. of clo. - 6i Both the diameters of the inferior outlet - 5/ The disadvantages of this pelvis are said to be prolapse and displacement of the viscera, sudden expulsion of the fcetus, inversion of the uterus, and want of the proper impress of rotation on the head. Retroversion of the uterus and its prolapse in the impregnated state, are said by some to be most commonly ob served in large pelves.
" Pekis cquabiliter justo minor."— In this pelvis, all the diameters are proportion ately diminished. The diminution is said,' by Churchill, to be generally about one-fourth. Naegele thinks it to be more common than had been supposed by Bandelocque and other writers on midwifery. Velpean gives two cases of " Etroilesse absolue' (Journal Com plementaire), in which the diminution was so great that one woman died undelivered, and the other underwent the Cmsarian operation.
It was considered by Alexander Shaw*, that proportionable contraction of the pelvic di ameters is very common in rickety subjects, from want of proper osseous development, and that it is generally accompanied by correspond ing diminution of the size of the bones of the lower extremities. The eNperience of Rokitan sky also favours the opinion that this propor tionate contraction, without distortion of the pelvis, may be produced by rickets. Naegele, however, records three female pelves affected with this deformity, which presented no ap pearance whatever of rickety change, neither in strength, weight, nor texture, one being even heavier than usual ; nor were there any rickety symptoms in their history. Two of the subjects died after severe instrumental labour ; and t'ne third, after one miscarriage, died undelivered of the second conception, from rupture of the uterus ; comparison with the child's head afterwards showing, that de livery of a living child would have been im possible Without the Cmsarian section. The diameters were generally above an inch less than the standard measurement. The ages of these subjects were from twenty-three to thirty-two years, showing that the contraction was an adult deformity. They were also about or above the average height. Women of low stature, indeed, have most commonly large pelves as well as large heads, and are not more liable to this deformity than those of taller stature ; the height of the individual being dependent, chiefly, upon the length. of the lower extremity and spinal column, which in these cases are disproportionate.
The pelvis of the true dwarf, however, in common,with, and in proportion to, the osseous system generally, is contracted and stunted in growth. In the Museum of the Edinburgh In firmary, is the skeleton of a male:adult dwarf, in which the pelvic pieces and epiphyses are not united by bone, but there is no distortion. The jaws are infantile. The pelvic bones in the well known skeleton of the female dwarf in the Hunterian Museum are in a similar incom plete condition. Sudden and universal "ar rest of development," is apparently the cause of this curious immature condition.