HYDATIDS SITUATED IN THE TRUE PELVIS. 163 



recto-vesical pouch, and produce the same effects as if 

 it had been developed in that situation. 



The cysts of the true pelvis frequently form 

 extensive and firm adhesions to the neighbouring 

 viscera, ; they compress the rectum, the bladder, and 

 the vagina, and they force the uterus and the bladder 

 either above or below their normal position, whilst 

 they also flatten or alter the shape of these two 

 organs by pressing them against the pubis, or some 

 other portion of the hard walls of the pelvis. 



Hydatid tumours often prevent the discharge of 

 the urine, by compression or displacement of the 

 bladder, or by the compression of the prostrate gland, 

 or of the urethra ; catheterism is sometimes impos- 

 sible, and the retention of the urine is complete. 



The compression which these tumoiu's exercise 

 upon the rectum soon occasions constipation, and at a 

 later period of the affection the passage of foecal 

 matter is totally prevented. Tliis obstacle to the 

 passage of the foeces causes hypertrophy of the 

 muscular fibres of the intestine above the seat of the 

 obstruction. A similar result has been observed in 

 the bladder, and in the ureters. 



A hydatid cyst in the pelvis, like a similar tumour 

 in any other region of the body, may occasion ulcera- 

 tion of the neighbouring viscera, and be thus brought 

 into communication with their cavities. It may 

 open into the bladder, or into the rectum, and be 

 completely emptied ; recovery occasionally follows 

 the discharge of the hydatid contents. No case is 

 recorded in which a hydatid cyst has spontaneously 

 opened into the vagina, or the uterus ; the rigidity 

 of the walls of the latter organ sufficiently explain 



M 2 



