Congenital Anomalies of Small and Large Intestines:

1) Intussusecption 

Intussusecption  is the invagination or telescoping  of one part of  the intestine into another part of  the intestine just beyond it or distal to it leading to the impairment of blood supply and necrosis of involved segment (Fig. 2.9). It is the most common cause of  intestinal obstruction during the first two years of  life. There are  three  forms of  intussuception, ileocolic, ileoilac and colocolic. Of  these three, ileocolic  is most common  in which the ileum invaginates into the'cecum and then into the ascending:  colon.  

Etiology:

The cause is usually unknown. Predisposing factors include acute enteritis, meckel's diverticulum, parasites, constipation, foreign body,  inspissated fecal matter in cystic fibrosis, lymphoma and infection with rotavirus or adenovirus. 

Assessment:

Child will present with episodic abdominal pain, which can be assessed by kicking movement of legs and drawing them up towards abdomen, vomiting and rectal passage of bloody mucus; the current jelly stool, fever and prostration. Abdomen is tender and distended. lnitially the infant may be comfortable between episodes of pain but later on infant becomes weak and  lethargic and a shock like condition develops. Fever rises to 41°C. On palpation of abdomen, a sausage shaped mass may be felt in the right upper quadrant. On rectal examination a ring of  intestine may be felt if  the intussuscepting part has reached  to the rectum. Diagnostic evaluation includes barium enema that shows the intestinal obstruction and rectal examiniation reveals blood and mucus. 

Pathophysiology 

When an upper portion of  the bowel invaginates into the lower portion, the mesentry  is carried into the lumen of the intesfine. The blood supply is cut off and necrosis and oedema occurs. This  results in  intestinal obstrucion. The end ol"  the invaginating part of intesting may extend into  transverse, descending or sigmoid colon or even to  the anus. There may be bleeding from the mucosa resulting in bloody stool. In some infants there may be spontaneous  teduction but in some cases strangulation of  the bowel may occur and child may have necrosis and perforation leading to peritonitis and death.