442 Intestinal Invagination. 



mediately affected portions of the peritoneum are, however, less 

 endangered (see page 416). 



In those very rare cases in which the patients remain alive 

 for a long time, the invaginated necrotic portion of intestine 

 may occasionally become detached ; if this does not occur and if 

 there has not been complete stenosis, the latter will then occur. 



Anatomical Changes. The two invaginated portions of 

 intestines form a curved, screwlike, or tortuous cylinder (Figs. 

 49 and 50) which is firm, sausagelike in consistency or fluctu- 

 ating. It is usually several centimeters long and occasionally 

 measures several meters long. In the latter case one can feel a 

 sausagelike body in the affected part. The bowel looks normal ex- 

 ternally, or purplish to dark bluish-red, because the folding of 

 the mesentery also compresses the veins of the outer portion. 

 At the end of the cylinder one sees the place of entrance of the 



k 



Fig. 50. Invagination of the small intestine in a dog. A. Place of entrance, B, coni- 

 cal end of the invaginated bowel. 



narrowed portion of bowel with its mesentery (intussusceptum) 

 into the most external layer of the wall composed of three 

 layers (intussuscipiens, see Fig. 48). AVall and mesentery of 

 the intussusceptum exhibit intense venous congestion. Where 

 the ingoing and outcoming portions of the intussusceptum are 

 in contact with each other, fibrinous peritonitis is soon devel- 

 oped, hence the pieces of intestines can be drawn apart only 

 with difficulty or not at all. An invagination which has been 

 formed during the agonal stage can easily be reduced and does 

 not show congestive or inflammatory changes. Invagination 

 is, as a rule, single, but it may l)e double, triple or quadruple. 

 Sometimes invaginations are found in several places. Finally, 

 one may find the evidences of a general peritonitis. 



