INTUSSUSCEPTION. 373 



distension of the bladder and rectum. A volvulus occasionally 

 involves the small intestine. 



The caecum may be obstructed in consequence of its becoming 

 acutely flexed on the colon ; the colon and caecum may become 

 twisted round their longitudinal axis, or the ascending, trans- 

 verse, and descending colon may form one large volvulus. 

 Strangulation is not so acute when the intestine is merely bent 

 at an angle instead of becoming twisted on its mesenteric axis. 

 In acute strangulation the vessels are obstructed, the bowel 

 becomes greatly congested and swollen, and the peritoneal coat, 

 which is the least distensible, is apt to tear. Peritonitis is an 

 early complication. 



Intussusception usually occurs in the neighbourhood of the 

 caecum, but it is also found in the jejunum, ileum, colon, and 

 rectum. It appears most likely to occur where a part of the 

 intestine which is more or less free joins a part which is com- 

 paratively fixed ; consequently the favourite sites for intussuscep- 

 tion are the caecal region, the lower end of the ileum, where 

 that becomes comparatively fixed before entering the colon, and 

 the junction of the pelvic colon with the rectum. In the ileo- 

 caecal variety, which up to recent time has been held to be the 

 commonest, the ileo-caecal valve, followed by the small intestine, 

 becomes prolapsed into the colon. In the ileo-colic form the 

 lower part of the small intestine becomes prolapsed and engaged 

 in the jaws of the valve. This form rarely attains a great size 

 of itself, but the end of the ileum, tightly gripped in the jaws of 

 the valve, is apt to form the starting-point of a new intussus- 

 ception of the ileo-caecal form. A compound intussusception 

 results, and this is now said to be the commonest variety. 

 Another form of compound intussusception may arise when an 

 enteric invagination reaches the valve, and, being unable to pass 

 through it, pushes it on in front. Whenever the ileo-caecal valve 

 is prolapsed the caecum and appendix become drawn into the 

 receiving sheath, the general rule being that intussusceptions 

 increase at the expense of the receiving sheath. The mesentery 

 being also drawn into the sheath by the portion of intestine to 



