Diverticulitis of the Colon: Imaging and Diagnosis

Introduction:

Diverticula is a small pouch that bulges outward from the colon of the large intestine. The presence of diverticula is called diverticulosis. It is more common in elderly people above the age of 60. Consuming a low-fiber diet has been a major cause of diverticulosis. Usually, it does not show any symptoms, but sometimes mild cramps, constipation, and bloating may occur due to diverticulosis. When diverticula become inflamed (swell) or infected, it results in diverticulitis. Diverticulosis and diverticulitis are together called diverticular diseases.

What Are the Symptoms of Diverticulitis?

• Abdominal pain (often in the lower-left side of the abdomen).

• Nausea (urge to vomit).

• Vomiting.

• Fever.

• Chills.

• Abdominal cramps in the lower part of the abdomen.

• Constipation.

In severe cases, diverticulitis results in rectal bleeding, blockages, or tears.

What Are the Risk Factors for Diverticular Disease?

• Elderly people aged above 40 years.

• Prevalent in men than females.

• Intake of low fiber diet.

• Smoking.

• Obesity (overweight).

• Nonsteroidal anti-inflammatory drugs (Ibuprofen, Aspirin or Opioids).

What Are the Diagnostic Tools Used to Detect Diverticulitis?

• Blood Test - The physician may advise a blood test for the diagnosis of diverticulitis. Due to the infection, there is an increased white blood cell count in diverticulitis.

• Stool Sample - The stool sample of the patients is evaluated to detect the presence of abnormal parasites or bacteria which might be a cause of abdominal pain, fever, and other symptoms.

• Digital Rectal Examination - For digital rectal examination, the physician inserts a lubricated glove finger into the patient's rectum to detect abnormalities of the anus and rectum.

• Barium Enema - During a barium enema, the barium-containing liquid is injected into the rectum. This liquid coats the outpouchings from the colon, which helps enhance the colon's abnormalities in x-rays. The size of each diverticulum ranges from millimeters to centimeters. The part of the colon involved with severe diverticulosis appears narrowed, hypertrophic muscular layer resembles a saw-tooth appearance. A barium enema is highly sensitive in the diagnosis of acute diverticulitis. If water-soluble contrast enema is used to detect acute diverticulitis, they become less reactive and have poor contrast details than barium. The most evident sign of diverticulitis with contrast enema is the extraluminal contrast, as the contrast may pass through the abscess cavity or sinus tract and enters the adjacent organ.

• Colonoscopy - Colonoscopy is used to examine the colon of the large intestine. In this scan, a thin tube with a camera at its end is inserted into the colon through the rectum. It visualizes any ulcers, bleeding, or abnormal growths found in the colon.

• Sigmoidoscopy - Sigmoidoscopy is helpful to visualize the sigmoid of the colon. This technique inserts a flexible thin tube into the sigmoid colon through the rectum. It contains light with a camera at the end, which provides video of the lumen of the sigmoid colon where most diverticula form.

• Angiography - Angiography helps determine heavy rectal bleeding. Angiography is performed by administration of contrast material into the arteries supplying the colon.

Imaging Techniques:

1) Ultrasonography-

• Ultrasonography is performed in diverticulitis patients with the convex array transducer placed transabdominal at about two to four MHz.

• Bowel wall thickening of more than four millimeters indicates diverticulitis. Swelling of the diverticula appears as round or oval and highly echogenic structures with a ring-down artifact.

• Inflammation of the pericolic fat is seen as an area of high echogenicity adjacent to the colonic wall.

• Abscess formation within the diverticula appears as well defined hypoechoic mass near the colon, and sometimes it might show shadowing, which indicates the presence of air.

• An abscess can be differentiated from adjacent bowel loops without peristalsis.

• Intra mural sinus tract is seen as an echogenic area with ring-down artifacts.

• Sometimes, ultrasonography gives false-positive results in the presence of a tumor or ischemic colon condition.

2) Computed Tomography-

• In computed tomography (CT) scan, the diverticulum appears as a small outpouching from the colon that contains air, barium, or fecal matter.

• Diverticulitis appears as an even thickening of the colon wall of about four to five millimeters. In distension, the diameter of the lumen measures less than one centimeter.

• The colon wall is usually enhanced as a high-attenuating inner and outer layer, and the middle layer shows low attenuation.

• The fluid collection inside the colon wall represents the intramural abscess.

• Extravasation of fluid and air into the peritoneal cavity or pelvis results from diverticular perforation.

• The presence of air bubbles in a peritoneal fluid near the sigmoid colon indicates peritonitis due to perforation of the diverticulum.

• Fistulas and the sinus tract appear as branching structures in the pericolic fat.

• Air in the urinary bladder with adjacent diverticulitis indicates a colovesical fistula. In such cases, intravenous contrast administration is not helpful, requiring intravenous contrast material for bladder enhancement.

• In about one-quarter of patients, an arrowhead-shaped collection of contrast agents between thickened folds indicates diverticulitis.

What Are the Differential Diagnoses of Diverticulitis?

1) Inflammatory Bowel Disease:

• Ischemic Colitis - Inflammation (swelling) of the colon results from decreased blood flow to the colon.

• Chron’s Disease - Inflammatory bowel disease that causes swelling of the digestive tract lining.

• Ulcerative Colitis - An inflammatory bowel condition that causes swelling of the innermost lining of the colon and rectum.

• Appendicitis - Swelling and infection of the appendix.

• NSAID Colitis - Inflammation of the colon occurs as a side effect of nonsteroidal anti-inflammatory drugs.

2) Non-inflammatory Bowel Disease:

• Irritable Bowel Disease - A disease of the large intestine that causes abdominal pain, cramps, and constipation resulting from various factors such as severe muscular contraction, stress, etc.,

• Colorectal Carcinoma - Tumor (cancer) of the colon or rectum.

• Hernia - A condition in which internal organs push out through a weak muscle or tissue spot.

• Volvulus - Twisting of the results of the intestinal loop in bowel obstruction.

• Foreign bodies.

3) Urogenital Diseases:

• Nephrolithiasis - Hard deposits made of salts or minerals inside the kidney, also called kidney stones.

• Ureterocele - Bulging of the end of the ureter inside the urinary bladder.

• Prostatitis - Swelling of the prostate gland.

Conclusion:

CT scan shows a high accuracy rate in the diagnosis of diverticulitis. CT scan helps evaluate the location, size, and extent of diverticulitis and its complications, such as sinus tract and abscess cavity. Ultrasonography showed about 85 percent sensitivity and 84 percent specificity in the detection of diverticulitis. Contrast enema was the choice of examination for diverticulitis before the advent of CT scans. However, barium enema remains the choice of imaging procedure in acute diverticulitis.