658 



UTERUS AND ITS APPENDAGES. 



uterine walls j while, between it and the mus- 

 cular parietes, there appears a new formation 

 of decidua, at first soft and delicate, but which 

 gradually acquires the peculiar characteristics 

 of that membrane. This layer is not thrown 

 off at birth, nor dispersed in the lochia, but 

 remains attached to the inner uterine surface, 

 and forms the foundation of the new mucous 

 membrane, with which, after labour, the ute- 

 rus is furnished. M. Robin supposes that 

 this new soft layer is often mistaken for a 

 product of inflammation occurring in puer- 

 peral and other uterine maladies. 



e. The uterus after parturition. 



Immediately after labour, the uterus, if 

 entirely empty, occupies the whole of the 

 pelvic cavity, together with the lower portion 

 of the hypogastric region. The bulk of the 

 organ varies in different individuals, and is 

 considerably greater after twin or multiple 

 pregnancy. 



The tissues generally are of a redder colour, 

 and softer, and more easily lacerable than in 

 the unimpregnated condition ; those of the 

 cervix being usually more lax than those of 

 the body, from infiltration of serum, and oc- 

 casionally, in parts, of blood. 



The cervical mucous membrane, which is 

 retained*, after labour exhibits here and there 

 sometimes slight lacerations, extending occa- 

 sionally into, or through, the proper tissue of 

 the part. In other respects, the internal aspect 

 of the cervical canal resembles that of the 

 same part in the last month of gestation, ex- 

 cept that the large and voluminous plica? (Jig. 

 446.) have become folded out and flattened 

 during the previous act of labour. Around 

 the margin of the internal os uteri may be 

 seen a thin ragged fringe marking the point 

 from which the decidua, here usually much 

 attenuated, had been torn away. 



The entire uterine cavity is denuded ; it 

 presents everywhere, except at the placental 

 space, a rough, flocculent, and sometimes 

 honeycomb-like surface, caused by the de- 

 tachment of a portion of the decidua and its 

 discharge along with the foetal membranes. 

 Another portion remains covering the mus- 

 cular structure of the uterus, but is in parts 

 so thin, that the latter appears to be left 

 nearly bare. 



The surface to which the placenta had 

 been attached forms usually one-third of the 

 entire inner superficies of the contracted 

 uterus. This, which is termed the placental 

 space, is easily distinguished by its uneven, 

 rugged, and somewhat nodulated appearance; 

 caused chiefly by the presence of numerous 

 large veins, whose truncated orifices obstructed 

 by coagula here protrude slightly above the 

 general level. 



Upon section, the uterine walls exhibit 

 everywhere the same laminated arrangement 

 of the proper tissues, with numerous inter- 

 mediately lying tortuous arteries and flat- 



* For the discussion of this question, see the 

 works of Heschl, Robin, and Kilian, hereafter 

 quoted. 



tened veins and sinuses, already described as 

 observable in the uterus during the latter pe- 

 riods of pregnancy (fig. 449.). 



These flattened thin-walled veins are usu- 

 ally empty, or contain a few unadherent coa- 

 gula. Those, however, which occupy the seat 

 of attachment of the placenta, where they are 

 much larger than in any other situation, are 

 filled with dark or greyish-red clots adherent 

 to their walls, and closing their mouths, which 

 terminate directly upon the uterine cavity. 



The peritoneal coat of the recently emptied 

 uterus is of a pale pinkish-white colour, and 

 presents a smooth, shining, and in parts a 

 slightly wrinkled surface. It is thicker and 

 less diaphanous than the same membrane be- 

 fore labour. 



The process of involution. No rapid or 

 material alteration in the size or composition 

 of the organ occurs during the first few days 

 after labour. In the course of the first week, 

 however, commences .a series of important 

 and interesting processes, continued during 

 the greater portion of the two months imme- 

 diately following labour, and having for their 

 object the restoration of the uterus to a con- 

 dition similar to, though not identical with, 

 its state before impregnation. These changes 

 consist in a gradual diminution in the weight 

 and dimensions of the organ accompanied by 

 a corresponding metamorphosis and ultimate 

 reconstruction of its tissues. They together 

 constitute the process commonly termed the 

 involution of the uterus, which will now be 

 examined. 



Changes in dimensions and 'weight. Accord- 

 ing to repeated estimates made by Heschl, 

 the weight of the uterus, immediately after 

 labour, ranges from lib. 6 7oz., ordinarily, 

 to 2lbs. 5 7oz.; the latter being the weight 

 after twin labour. 



The dimensions depend upon the degree of 

 contraction. Under ordinary circumstances, 

 the entire length is 8 10 inches, and the 

 thickness of the parietes 1 inch. These first 

 changes in the dimensions of the organ, as 

 compared with the state previous to labour, 

 are effected solely by the contraction of the 

 uterine fibre. They consist chiefly in a re- 

 arrangement of relative position in the com- 

 ponent tissues, by which, while the entire 

 substance of the uterus remains undiminished, 

 its length and breadth are greatly reduced, and 

 the thickness of the parietes correspondingly 

 increased. In one respect, however, the en- 

 tire bulk* and weight are less than they were 

 before labour, because a much smaller quan- 

 tity of blood now circulates in the walls, but 

 the solids remain unaltered. 



At the end of the first week, the diminution 

 of the organ is not very considerable. Its 

 weight is merely reduced from 1 Ib. 6 7 oz. 

 to lib. 3 4oz. At the end of the second 

 week, the rate of diminution is found to have 

 been much more rapid ; the organ now weighs 

 only 10 1 loz. At the end of the fifth week, 

 5 6oz.; and in the course of the second 

 month, it is reduced to its ordinary weight of 

 1 to 2oz. j but it never entirely regains the 



