648 



THE URINARY ORGANS. 



the obstruction occurs suddenly or is complete, the wall of the bladder is thinned. 

 When an incomplete obstruction exists for some time the walls of the bladder are apt 

 to hypertrophy, so that, although the bladder is larger than normal, the walls may not 



only be of the usual thickness, but even 

 very much thicker. In the foetus dila- 

 tation of the bladder may reach such a 

 size as to interfere with delivery. 



The retained urine in dilated blad- 

 ders is liable to decomposition, from 

 the presence of bacteria, and this may 

 lead to inflammation or gangrene of 

 the mucous membrane. 



DIVEUTICULA of the bladder may 

 be produced by the pouching out of cir- 

 cumscribed portions of the wall of the 

 bladder, the wall of the pouch contain- 

 ing all the layers of the bladder wall. 

 More frequently, however, they are 

 produced by a protrusion of the mu- 

 cous membrane between hypertrophied 

 bundles of muscle fibre. They may 

 be very small (Fig. 411), or they may 

 be as large as a child's head. They 

 may communicate with the bladder by 

 a large or small opening. The decom- 

 position of stagnant urine in diverticu- 

 la is apt to induce inflammation. Cal- 

 culi may be formed in them or may 

 slip into them from the bladder. 



HYPERTROPHY of the muscular 

 coat of the bladder is usually due to 

 mechanical obstructions to the outflow 

 of urine, such as stricture of the ure- 

 thra, enlarged prostate, calculi, new 

 growths, etc. The muscular coat is 

 thickened uniformly or assumes a trabeculated appearanee (Fig. 410). The organ re- 

 tains its normal capacity, or is dilated, or becomes smaller. The mucous membrane is 

 frequently the seat of chronic or acute inflammation. Dilatation of the ureters and 

 hydronephrosis frequently accompany this condition. 



HERNIA of the bladder sometimes accompany intestinal hernia} through the ingui- 

 nal and crural canals and the foramen ovale. The changes in position of the bladder, 

 produced by displacements of the vagina and uterus, will be mentioned with the 

 lesions of those organs. 



In the female the base of the bladder may press downward, causing protrusion of 

 the vaginal wall (vaginal cystocele) ; or there may be inversion and prolapse of bladder 

 through the dilated urethra. 



FIG. 410. HYPERTROPHY OF THE WALL OF THE 

 BLADDER. 



WOUNDS RUPTURE PERFORATION. 



Penetrating wounds of the bladder may permit escape of urine into 

 the abdominal cavity, or infiltration into the surrounding connective 

 tissue or permanent fistulse. Such wounds are always serious and fre- 

 quently fatal, owing chiefly to the severe and often gangrenous inflam- 

 mation which decomposing urine sets up in the connective tissue, or to 

 the peritonitis induced by the same cause. * 



