PELVIS. 



185 



Distortions affecting the whole pelvis. In 

 these cases the pubic bones are always more or 

 less extensively implicated in the distortion, and 

 entering, as they do, into the formation of 

 both brim, cavity, and outlet, all these parts 

 of the pelvis are contracted or mispropor- 

 tioned. At the brim, however, the obstruc- 

 tion usually takes place, while the operations 

 necessary to procure delivery through the 

 natural passages are rendered more difficult 

 by the distortion of the cavity and inferior 

 opening. 



General distortions of the pelvis are com- 

 monly divided into three kinds, named, from 

 the shape of the brim, the ovate or elliptical, 

 the cordiform or angular, and the obliquely 

 ovate. 



The ovate, elliptical, or reniform pelvis. 

 In this distortion the sacrum is placed almost 

 horizontally, so that the sacral promontory pro- 

 jects forward to a great degree, generally at the 

 same time deviating from the median line, and 

 considerably sunk in a direction forwards 

 and downwards, so that the lowest lumbar 

 vertebra forms the most projecting point. 

 The lateral sacral curve is diminished, flat- 

 tened out, and often bent backwards on each 

 side the promontory. The vertical curvature 

 is generally diminished and flattened in some 

 degree, and directed more downwards by the 

 more horizontal position of the bone; but 

 occasionally there is an acute bend forwards 

 at the lower part. The coccyx is generally 

 bent acutely forwards. 



The ilia and ischia on each side are often 

 removed to a greater lateral distance than 

 normal. The iliac wings are flattened and 

 directed more forward ; and the cotylo- 

 sacral arch is more sharply curved, and often 

 shorter and thicker than normal. The planes 

 of the ischia diverge instead of slightly con- 

 verging downward ; the spines and tuberosities 

 being likewise divergent, and the latter di- 

 rected more outwards and backwards. The 

 superior rami of the pubes are generally flat- 

 tened out, having little anterior projection ; 

 while the inferior rami are widely divergent, 

 affording a wider and shallower expansion of 

 the sub-pubic arch. In some cases, however, 

 the sub-pubic arch is little altered 



In some instances the symphysis of the 

 pubis presents the appearance of being in- 

 dented or pushed backwards, giving an out- 

 line to the brim of an hour-glass shape. 



The diameter principally diminished is the 

 conjugate of the brim, and often one or other 

 of the oblique diameters. In one variety the 

 transverse diameter of the brim is also con- 

 tracted. The transverse diameter is, however, 

 sometimes undiminished, or even increased. 

 The transverse diameter of the inferior outlet is 

 generally most considerably increased ; but the 

 antero-posterior diameter is most usually con- 

 tracted by the bend in the sacrum. In many 

 instances, however, it is considerably enlarged. 

 The depth of the true pelvis is generally dimi- 

 nished, and its capacity lessened. 



The sacro-vertcbral angle is generally much 



diminished, from the backward horizontal di- 

 rection of the upper end of the sacrum. 



The inclination of the superior plane is some- 

 times increased so much as to be vertical ; the 

 axis of the brim being generally directed more 

 forward than in the " standard" and that of 

 the inferior outlet more backward. Some- 

 times, however, they are very little altered. 



The structure of the bones is light, slender, 

 and fragile, indicating the origin of the dis- 

 tortion in rickety softening. 



Examples of this kind of pelvis are nu- 

 merous. One of the most well-known is that 

 of Elizabeth Sherwood, who was delivered by 

 Dr. Osborne by means of the crochet. The 

 measurements of this pelvis are given as fol- 

 lows : From the most prominent point of the 

 lumbar vertebra to the upper border of the 

 pubic symphysis, li inch. From the same 

 point on the left side to the left pectineal 

 eminence, If inches. The same measurement 

 on the right side, 1| inches. From the sacral 

 promontory to the pubic symphysis, 1 inch. 

 Transverse diameter of brim, 5 inches. Left 

 oblique ditto, 4 inches. Right oblique, 4 

 inches. Antero-posterior of cavity, 2\ inches. 

 Transverse ditto, 5 inches. Antero-posterior 

 of outlet, 2% inches. Transverse, 4 inches. 

 Sub-pubic angle, 100. 



The measurements of a very extreme case 

 of this kind of distortion are recorded by Dr. 

 Ramsbotham (see^/%. 117.) as follows: 



Fig. 117. 



Ovate pelvis. (After Ramsbotham.} 



Conjugate or sacro-pubic diameter of brim, 

 | of an inch only. From right side of sacral 

 promontory to right pubis, \\ inch. The 

 same measurement on the left side, If inch. 

 Antero-posterior diameter of outlet, 2 inches. 

 Transverse diameter, 4 inches. The shape 

 of the brim in this pelvis is hour-glass, the 

 pubic symphysis being pushed back. Such a 

 pelvis, in the opinion of the above-named 

 writer, would necessitate the abdominal 

 section. 



In a less extreme case, given by the same 

 writer, the sacral promontory and lumbar 

 curve bend much more considerably towards 

 the left side. At the brim, the conjugate dia- 

 meter is 1 inch; the right sacro-pubic, 2 



