Ever heard of diverticulitis?
Pathophysiology: Diverticulosis is defined as the condition of having diverticula. Diverticulitis is defined as an inflammation of one or more diverticula. Diverticula are small mucosal pockets in the wall of the colon that conceivably fill with stagnant fecal material or undigested food particles. Obstruction of the neck of the diverticulum may result in the distention of the diverticulum secondary to mucus secretion and overgrowth of normal colonic bacteria.
The thin-walled diverticulum, consisting solely of mucosa, is susceptible to vascular compromise and, therefore, is at risk for microperforation or macroperforation. Infection subsequently may extend through the wall of the colon into the peridiverticular tissue and cause peridiverticulitis. Inflammation is frequently mild, and the pericolic fat and mesentery can wall-off a small perforation. However, the walled-off infection can progress to localized abscess formation. Less commonly, rupture of the abscess may occur with generalized peritonitis.
If adjacent organs are involved, fistulae can develop. The most common is a colovesicular fistula (colon to urinary bladder). This is observed almost exclusively in men and in women following hysterectomy, probably because of the interposition of the uterus between the sigmoid colon and the urinary bladder. Colovaginal and colocutaneous fistulae are much less common.
Recurrent attacks of diverticulitis can result in the formation of scar tissue, leading to narrowing and obstruction of the colonic lumen. Diverticulitis can occur anywhere in the gastrointestinal tract but is most commonly observed in the colon. Small bowel diverticulitis is far less common than colonic diverticulitis. Asymptomatic diverticulosis is a common condition, but few patients with diverticula develop symptomatic diverticulitis. While diverticulitis is generally considered a disease of the elderly population, as many as 20% of patients with diverticulitis are younger than 50 years. Diverticulitis may be a more severe illness when observed in younger patients; however, some controversy exists about this, and the apparent increased severity may be an artifact of delayed diagnosis.
Because diverticula and, hence, diverticulitis can develop anywhere in the gastrointestinal tract, symptoms may mimic multiple conditions.
Diverticulitis in the transverse colon may mimic peptic ulcer disease, pancreatitis, or cholecystitis.
Diverticulitis in the right colon may be confused with acute appendicitis.
With disease progression, localized abscess and phlegmonous formation may occur. Systemic signs of infection, such as fever and leukocytosis, become more pronounced.
Localized peritonitis may lead to direct and rebound tenderness over the involved area. On physical examination, rebound tenderness is generally most pronounced in the left lower abdominal quadrant. The abdomen may become distended and tympanic to percussion. Bowel sounds may become diminished or absent. Sometimes, a mass may be felt at the site of the inflammation. This may be apparent not only on abdominal palpation but also on pelvic or rectal examination.
Elderly patients and those taking corticosteroids may have unremarkable findings on physical examination, even in the presence of severe diverticulitis. Such patients must be approached with a high index of suspicion, in order to avoid a significant delay in arriving at the correct diagnosis.
Hematochezia, or bright red blood per rectum, is not a symptom of diverticulitis, although occult blood in the stool is present in approximately 25% of patients with diverticulitis. When hematochezia is noted, other causes (eg, hemorrhoids, neoplastic disease, colitis, vascular ectasias, arterial bleeding from diverticulosis) should be considered.
If a colovesicular fistula is present, urinary tract symptoms, including dysuria, urgency, pneumaturia, fecaluria, and recurrent urinary tract infections, may be prominent. Patients with colovaginal fistulas may present with a purulent vaginal discharge.
Leg pain, possibly associated with thigh abscess, and leg emphysema secondary to retroperitoneal perforation from diverticulitis have been reported.
The etiology of diverticulitis remains unclear, but a low-fiber diet is considered a predisposing factor. Diets that are low in fiber lead to low-bulk stool, which, in turn, causes an increase in segmentation of the colon during propulsion. Intraluminal pressure is increased, and diverticula are created. Diets that are high in fat and beef content are thought by some to cause increased intraluminal pressure.
Aging causes changes in collagen structure that may lead to a weakening of the colonic wall.
Colonic motility disorders, ingestion of corticosteroids, and ingestion of nonsteroidal anti-inflammatory drugs may be predisposing factors.
Genetics is also believed to play a role, as evidenced by the fact that Asian people tend to have a predominance of right-sided diverticula, while Western people tend to have left-sided disease.