Diverticular disease
Diverticular disease is a disorder characterized by bulging pouches (diverticula) in the GI wall that push the mucosal lining through the surrounding muscle. The most common site for diverticula is in the sigmoid colon, but they may develop anywhere, from the proximal end of the pharynx to the anus. Other typical sites are the duodenum, near the pancreatic border or the ampulla of Vater, and the jejunum. Diverticular disease of the stomach is rare and may be a precursor of peptic or neoplastic disease. Diverticular disease
of the ileum (Meckel’s diverticulum) is the most common congenital anomaly of the GI tract. (See Meckel’s diverticulum.)
of the ileum (Meckel’s diverticulum) is the most common congenital anomaly of the GI tract. (See Meckel’s diverticulum.)
Diverticular disease has two clinical forms. In diverticulosis, diverticula are present but don’t cause symptoms. In diverticulitis, a far more serious disorder, diverticula become inflamed and may cause obstruction, infection, and hemorrhage.
Most common in adults ages 45 and older, diverticular disease affects about 30% of adults older than age 60. Diverticulosis is less common in nations where diets contain abundant natural bulk and fiber.
Causes
A diverticulum develops when high intraluminal pressure is exerted on weaker areas (for example, points where blood vessels enter the intestine), causing a break in the muscular continuity of the GI wall. The pressure in the intestinal lumen forces the intestine out, creating a pouch (diverticulum).
Diet, especially highly refined foods, may be a contributing factor. Lack of fiberreduces fecal residue, narrows the bowel lumen, and leads to higher intra-abdominal pressure during defecation.
Diverticulitis occurs when retained undigested food mixed with bacteria accumulates in the diverticulum, forming a hard mass (fecalith). This substance cuts off the blood supply to the diverticulum’s thin walls, increasing its susceptibility to attack by colonic bacteria. Inflammation follows bacterial infection.
Complications
Diverticulitis causes most complications. In severe diverticulitis, the diverticula can rupture, producing abscesses or peritonitis. Diverticular rupture occurs in up to 20% of patients with severe diverticulitis.
Diverticulitis may also lead to intestinal obstruction, resulting from edema or spasm related to inflammation or, in chronic diverticulitis, from fibrosis and adhesions that narrow and seal the bowel lumen.
Other complications include rectal hemorrhage or portal pyemia (generalized septicemia with abscess formation) from arterial or venous erosion. Occasionally, the inflamed colon segment may produce a fistula by adhering to the bladder or other organs.
Meckel’s diverticulum
In Meckel’s diverticulum, a blind tube (such as the appendix) opens into the distal ileum near the ileocecal valve. This congenital abnormality results when the intra-abdominal portion of the yolk sac fails to close completely during fetal development. It occurs in about 2% of the population, mostly in males.
Complications
Uncomplicated Meckel’s diverticulum produces no symptoms and therefore requires no treatment. However, the abnormality can cause melena and abdominal pain, especially around the umbilicus. The lining of the diverticulum may be either gastric mucosa or pancreatic tissue. This disorder may lead to peptic ulceration, perforation, and peritonitis and may resemble acute appendicitis.
Meckel’s diverticulum may also cause bowel obstruction when a fibrous band that connects the diverticulum to the abdominal wall, the mesentery, or other structures snares a loop of the intestine. This may cause intussusception into the diverticulum, or volvulus, near the diverticular attachment to the back of the umbilicus or another intra-abdominal structure.
Meckel’s diverticulum should be considered in patients with GI obstruction or hemorrhage, especially when routine GI X-rays are negative.
Treatment
Meckel’s diverticulum is treated by surgical resection of the inflamed bowel and antibiotic therapy (if infection occurs).
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