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==Description==

==Description==

'''Intussusception''' is the invagination of one portion of the gastrointestinal tract into the lumen of the adjoining portion.  The intussusceptum is the invaginated segment and the intussuscipien is the enveloping segment.

'''Intussusception''' is the invagination of one portion of the gastrointestinal tract into the lumen of the adjacent portion.  The intussusceptum is the invaginated segment and the intussuscipien is the enveloping segment.

    

    

Intussusception results from vigorous contractions due to intestinal irritation, which force a segment of an intestine to teloscope into the lumen of a more relaxed adjacent segment.  A normograde intussusception is the most common, but retrograde intussusception has also been reported.  Intussusception normally occurs due to gastrointestinal disease, although it is often hard to identify the cause.  Parasites, infectious enteritis, metabolic disorders, foreign bodies, history of recent intestinal surgery, intestinal masses have all been known to associate with intussusception.  Chronic intussusception can occur with little haemodynamic changes.

Intussusception results from abnormal peristalsis. Vigorous contractions force a segment of intestine to teloscope into the lumen of a more relaxed adjacent segment.  A normograde intussusception is most common, but retrograde intussusception has also been reported.   

Intussusceptions can occur along any length of the intestine, however, [[Colon - Anatomy & Physiology #Structure|ileocolic]] and jejunojejunal intussusceptions are the most common.  More caudal intussusception can cause it to protrude from the rectum.  This has to be distinguished from a rectal prolapse.  In intussusception, it is possible to pass a probe next to the anus, but not in [[Rectal Prolapse|rectal proplapse]].

Intussusceptions can be classified according to their location in the gastrointestinal tract. They occur more commonly in regions where there is a significant change in lumen diameter, such as ileocolic and gastroesphageal. [[Colon - Anatomy & Physiology #Structure|ileocolic]] and jejunojejunal intussusceptions are the most common.  More caudal intussusception can cause it to protrude from the rectum.  This has to be distinguished from a rectal prolapse.  In intussusception, it is possible to pass a probe next to the anus, but not in [[Rectal Prolapse|rectal proplapse]].

Initially, a partial obstruction results.  Overtime, this progresses to a complete obstruction, with obstruction of venous return, arterial occlusion and avulsion of vessels.  The intestinal walls become oedematous, ischaemic and turgid, resulting in devitalisation if not treated.  Adhesion can occur in long standing cases due to fibrin deposition.

Initially, a partial obstruction results.  Overtime, this progresses to a complete obstruction, with obstruction of venous return, arterial occlusion and avulsion of vessels.  The intestinal walls become oedematous, ischaemic and turgid, resulting in devitalisation if not treated.  Adhesion can occur in long standing cases due to fibrin deposition.

An inflammatory exudate is released from the serosal surface, fibrinous adhesions may form between surfaces making the structure irreducible this may progress to necrosis of the tissue.  

An inflammatory exudate is released from the serosal surface, fibrinous adhesions may form between surfaces making the structure irreducible this may progress to necrosis of the tissue.  

There is functional obstruction to bowel. May rupture, leading to peritonitis and death.  

There is functional obstruction to bowel. May rupture, leading to peritonitis and death.  

 

*Associated with any condition that increases peristalsis  

*Associated with any condition that increases peristalsis  

** Enteritis

** Enteritis