440 



Intestinal Tuva,i;inatioii. 



As predisposing causes must ))e considered the firmer at- 

 tachment by a short mesentery of some portions of the intes- 

 tine, a heavy tumor, adhesions, occasionally also bloating. 



The seat of an invagination is most frequently the small in- 

 testine, since it is especially subject to stronger contrac- 

 tions; more rarely the ileum becomes invaginated into the 

 cecum, exceptionally into the colon ( Johne) ; in horses, cattle 

 and dogs, the apex of the cecum into its body; in horses and 

 exceptionally also in dogs the cecum into the colon, rarely the 

 sinall colon into itself or into the rectum. There has also been 

 observed invagination of the duodenum into the stomach (H. 

 Bouley in a horse, and Peuch and Cadeac each in one dog). 

 This occurrence must have been due to antiperistalsis which 

 may also cause invagination in other portions of the intestinal 

 tract into a section situated towards the stomach. 



Fiji. 48. Diagrammatic representation of invagination. 



a. internal, b. external portion of the intussusceptuni, 



d. its mesentery, c. iytussuscipiens. 



Pathogenesis. 

 Wherever invagina- 

 tion occurs, the in- 

 tussuscepting portion 

 will, of necessity, 

 draw along its mes- 

 entery with the 1)lood 

 vessels of the latter 

 (Fig. 48). Theintus- 

 suscepting portion 

 and its mesentery 

 will be subjected to 

 a certain amount of 

 pressure, depending 

 upon the caliber of 

 the intussuscepted 

 section; this will 

 -^ cause congestion, 



swelling and subsequently a hemorrhagic serous infiltration of 

 the drawn-in portion of the intestine and its mesentery. The 

 extravasating hemorrhagic fluid gets into the lumen, also be- 

 tween the invaginating and the invaginated portions, and also 

 to a small extent into tlie free peritoneal cavity at the place of 

 entrance of the invaginating portion. 



Passive congestion, which increases rapidly in the intus- 

 suscepted portion, causes marked convulsive contractions with 

 colicky pains, and the former may cause an increase of the por- 

 tion invaginated towards the anus. This is favored by the fact 

 that while the circular fibers of the intussuscepted portion con- 

 tract, the longitudinal fibers of the intussuscepting section like- 

 wise contract. If the place of invagination is somewhat fixed, 

 the latter section will slip over the former. Contraction of the 

 circular fibers of the invaginating portion of the intestine may 

 cause an increase in the invaginated portion, because the con- 



