Drawing of<unk> In the most frequent type of<unk>  the ileum enters the cecum. However, other types occur, such as when a part of the ileum or jejunum prolapses into itself. The part that prolapses into the other is called the intussusceptum, and the part that receives it is called the intussuscipiens. Almost all<unk>  occur with the intussusceptum having been located proximally to the intussuscipiens. This is because peristaltic action of the intestine pulls the proximal segment into the distal segment. There are, however, rare reports of the opposite being true. An anatomic lead point (that is, a piece of intestinal tissue that protrudes into the bowel lumen) is present in approximately 10% of<unk> . The lead point (best exemplified by a polyp) serves as a focal area of traction, which the peristaltic action pulls into the distal bowel, thus invaginating the attached bowel segment. The trapped section of bowel may have its blood supply cut off, which causes ischemia (lack of oxygen in the tissues). The mucosa (gut lining) is very sensitive to ischemia, and responds by sloughing off into the gut. This creates the classically described "red currant jelly" stool, which is a mixture of sloughed mucosa, blood, and mucus. A study reported that in actuality, only a minority of children with<unk> had stools that could be described as "red currant jelly", and hence<unk> should be considered in the differential diagnosis of children passing any type of bloody stool.
Intussusception 
Pyloric stenosis
Meckel's diverticulum
Vesicointestinal fistula
Enterocele
Meconium peritonitis
Rectal foreign body
Intestinal malrotation