Sunday, March 13, 2005

Intussusception

Intussusception occurs when a segment of bowel telescopes (similar to closing of a telescope) into a segment just distal to it. It is the most common cause of intestinal (bowel) obstruction (blockage) between 3 months and 6 years of age. The ileocolic (small bowel into the colon) intussusception is the most common type although it may occur anywhere in the small bowel and colon.

Anatomy


The demarcation between the duodenum (1st part of small bowel) and the jejunum (2nd part of small bowel) is the ligament of Treitz (see Surgery of the Duodenum) (Figure 1)

The jejunum makes up about one third of the proximal small bowel

The ileum is the distal two thirds of the small bowel

The jejunum, ileum, and associated mesenteries (supporting and suspending structures) are attached to the back wall of the abdomen. They are completely covered with peritoneum (single layer of cells that line the surface of the abdomen and bowel)

The ileum joins the cecum (first part of the colon) in the right lower quadrant at the ileocecal valve near the appendix

The small bowel possesses an extensive lymphatic network that aids in the absorption of nutrients. It drains from the bowel wall into adjacent lymph vessels and lymph nodes and ultimately getting into larger lymphatics that finally empty into the left subclavian vein. The lymphatics of the small bowel play a major role in immune response (response to infection)
Pathology


The telescoping process is known as intussusception (Figure 2)

The leading proximal segment (intussusceptum) almost always telescopes into the distal segment (intussuscipens)

There may be a leading edge in the form of a polyp, inverted appendiceal stump, Meckel's diverticulum (See Surgery of the Jejunum and Ileum) or tumor

The leading edge gets caught up in the downstream peristalsis (wavelike action of the bowel wall that propels food) and is pulled into the distal bowel

In most cases the cause is unknown but viruses are thought to induce hyperplasia (increased size) of Peyer's patches (lymphoid tissue) in the end of the ileum

posted by Intussusception Medical Care Amateur - @ Intususseption: Intussusception