374 CLINICAL APPLIED ANATOMY. 



which it is attached, intense engorgement of the intussuscepted 

 bowel occurs, leading to the passage of blood and mucus, and some- 

 times to sloughing of the intussusceptum. The traction on the 

 mesentery also confers a characteristic curve on the intus- 

 susceptum, and may cause its orifice to be tilted against the 

 side of the receiving layer. Complete obstruction of the bowel 

 or sloughing of the receiving layer at the point of pressure may 

 result. The tumour, consisting as it does of muscular bowel, 

 may sometimes be felt to harden and relax during examination. 

 The highly oedematous and inflamed apex of an enteric intus- 

 susception may easily be mistaken for the ileo-caecal valve. A 

 polyp is often the starting-point of an intussusception in the 

 adult, and in childhood inflamed Peyer's patches or invaginated 

 saccules of the colon are believed to act in a similar manner. 



Intussusceptions during their progress follow the direction of 

 the colon, and in some cases protrude from the anus. For an 

 intussusception arising in the csecal region to do this it is 

 obvious that either an extensive mesocolon must be present, 

 or the colon and its mesentery must be stripped away from the 

 posterior abdominal wall. 



A moment's reflection will show that the easiest way to reduce 

 a tight intussusception is by compression from below aided by 

 traction of the outer layer downward over the intussusceptum, 

 thus causing reduction by gradually unrolling the outer tube in 

 the reverse way to that in which the imagination was brought 

 about. Upward traction on the intussuscepted layer causes the 

 unfolding to occur at the apex of the entering tube ; this process 

 is resisted, and tends to throw the inner tube into folds, further 

 wedging it in the bowel. But intestine prolapsed through the 

 ileo-csecal valve usually has to be reduced by upward traction. 



Obstruction of the Bowel by Gall Stones. A gall stone large 

 enough to become impacted in the bowel must of necessity have 

 entered it by ulceration, and not by passage along the bile ducts. 

 The relations of the gall bladder render it possible for a stone 

 to enter either the duodenum or the colon in this way, but entry 

 into the duodenum is by far the commoner and more serious 



