Diverticular disease

Diverticular disease is an umbrella term for a spectrum of intestinal pathologies characterized by abnormal outpouching of the colonic mucosa (diverticula). Diverticulosis refers to the presence of asymptomatic diverticula, while diverticulitis refers to symptomatic diverticular inflammation. The condition is considered a lifestyle disease, seen especially in industrialized nations with low fiber diets and slow fecal transit (e.g., from lack of exercise). Incidence increases with age and more than 50% of individuals are affected by the 7^th decade of life. Diverticula are caused by increased intraluminal pressure in the distal colon, resulting in herniation of the inner colonic wall through areas of weakness in the outer muscular layer. This may occur in any part of the colon but is especially common in the sigmoid colon. Most patients are asymptomatic but may present with lower left abdominal pain, change in bowel habits, and fever in the event of diverticulitis. Diagnosis is based on the clinical features and elevation of inflammatory markers in blood tests. Abdominal CT scan is the imaging method of choice and indicated to assess the extent of the disease as well as potential complications. Colonoscopy is contraindicated during acute inflammation but is essential in ruling out malignancy in follow-ups. Uncomplicated diverticulosis may be managed conservatively with antibiotics and bowel rest, while complicated cases may require surgery with colonic resection. Further intervention may be indicated if complications such as diverticular bleeding, perforation, or abscesses arise. Elective surgery is recommended for patients with recurrent diverticulitis or associated conditions such as strictures and fistulae.

• Diverticula: pouches protruding from the colon wall
  • True diverticula: affect all layers of the intestinal wall; rarely occur and are often congenital; manifest mainly in the cecum
  • Pseudodiverticula: not all layers of the intestinal wall protrude; the diverticulum is only covered by a layer of mucosa and submucosa, not by a muscular layer
• Diverticulosis: merely describes the presence of asymptomatic diverticula
• Diverticulitis: describes the inflammation of diverticula resulting in clinical symptoms

• Caused mainly by lifestyle and environmental factors
  • Increasing age
  • Genetic factors
  • Diet (low-fiber, rich in fat and red meat)
  • Obesity, low physical activity
  • Cigarette consumption

References:^[2][3]

• Diverticulosis
  • Chronic constipation; and increasing weakness of connective tissue due to age → protrusion of herniated intestinal mucosa and submucosa through gaps in the muscular layer of the intestinal wall (Tunica muscularis)
  • Localized particularly in the sigmoid colon (75% of cases)
• Diverticulitis: stool gets lodged in diverticula → obstruction of intestinal lumen → increased intraluminal pressure and erosion of diverticula wall → inflammation

References:^[2]

Diverticulosis

• Mostly asymptomatic
• Most common cause of lower GI bleeding in adults
• Can present with abdominal pain in patients with chronic constipation

Diverticulitis

• Low-grade fever
• Sigmoid colon most commonly affected → left lower quadrant pain
• Possibly tender, palpable mass (pericolonic inflammation)
• Change in bowel habits (∼ 50% constipation, 25–35% diarrhea)
• Nausea and vomiting; caused by bowel obstruction or ileus
• ↑ Urinary urgency and frequency (∼ 15%)
• Acute abdomen → indicates possible perforation and peritonitis

In elderly or immunocompromised patients clinical symptoms may only be mild!References:^[2][4][5]

Laboratory tests

• Blood tests
  • Leukocytosis
  • ↓ hemoglobin (in diverticular bleeding)
  • ↑ CRP (> 5mg/100ml)
  • Metabolic panel
    • Electrolytes: imbalance in patients with vomiting and diarrhea
    • Liver tests and lipase: rule out hepatic or pancreatic cause for abdominal pain
    • Kidney tests: assessment of renal function prior to contrast CT
• Urinalysis: leukocytosis; colonic flora in urine culture (indicates a colovesical fistula)
• Stool test: rule out pathogens in patients with diarrhea
• Pregnancy test: rule out ectopic pregnancy in women of childbearing age

Imaging studies

• 1^st-line: abdominal CT with oral and IV contrast: :
  • Diverticula, bowel wall thickening (> 4mm), inflammation of the pericolonic fat with fat stranding (visible traces of fluid in the fat)
  • Assessment of complications
    • Abscess: fluid collections, surrounding inflammatory changes
    • Obstruction: dilated intestinal loops, visualization of air-fluid levels
    • Perforation: free air in the abdominal cavity in the event of perforation
    • Fistula: air in organs other than the bowel
• Abdominal ultrasound
  • Performed if CT is not available
  • Shows diverticula, hypoechoic peridiverticular inflammation, abscess formations (detecable fluid), bowel wall thickening
• Abominal x-ray: not useful in diagnosing diverticulitis; detects complications, such as abscesses, obstructions and ileus (intestinal dilation, air-fluid levels)

Colonoscopy

• Not indicated during an acute episode → ↑ risk of perforation and exacerbating diverticulitis
• Performed once inflammation has subsided (after 6 weeks) to assess extent of diverticulitis and rule out malignancy
• Asymptomatic diverticulosis is often an incidental finding during routine endoscopy

Performing a colonoscopy during the acute phase of diverticulitis should be avoided due to risk of perforation!

References:^[2][4][5][6]

• Differential diagnostic considerations: Crohn's disease and ulcerative colitis
• Intestinal ischemia (ischemic colitis)
• Colorectal cancer
• Acute appendicitis
• Ileus , colonic obstruction

The differential diagnoses listed here are not exhaustive.

Diverticulosis

• No treatment can reverse the growth of existing diverticula
• Prevention of progression
  • Regulation of bowel movements
  • Increase physical activity
  • High-fiber diet
  • Plenty of fluids

Treatment of diverticulitis

Disease	Conservative management	Surgical management
(Acute) uncomplicated diverticulitis	Outpatient treatment Restricted, clear liquid diet and bowel rest until pain improves Broad-spectrum oral antibiotics for 7–10 days Ciprofloxacin plus metronidazole Trimethoprim/sulfamethoxazole plus metronidazole Amoxicillin-clavulanate Pain management, if necessary (e.g., acetaminophen, ibuprofen)[7]	Not necessary unless conservative methods fail or there is high risk of recurring episodes
(Acute) complicated diverticulitis	Inpatient treatment IV fluids and bowel rest Broad-spectrum IV antibiotics Piperacillin/tazobactam Ampicillin/sulbactam Imipenem, meropenem Pain management(e.g., acetaminophen, ketoprofen, morphine); often severe due to localized peritonitis
		CT-guided percutaneous abscess drainage Indications: stable patient with abscess > 3 cm Emergency surgery Indication: in case of peritonitis, sepsis or intestinal obstruction Resection of the affected segment; primary anastomosis or temporary, protective ileostomy Alternatively Hartmann procedure Elective surgery Indication: recurrent disease unresponsive to antibiotics; complicated diverticulitis in young patients Resection of the affected segment once the acute inflammation has passed Management of complications in recurring diverticulitis (e.g., intestinal strictures, fistulas)

References:^[4][6][7]

• Diverticular bleeding
  • Frequency: occurs in around 5% of cases of patients with diverticulosis
  • Caused by erosions around the edge of diverticula
  • Clinical findings
    • Painless hematochezia
    • Severe or ongoing bleeding: significant drop in hemoglobin, hemodynamic instability (hypotension, tachycardia, dizziness, reduced level of consciousness)
    • In 70–80% of cases bleeding ceases spontaneously
  • Differential diagnosis: other causes of lower gastrointestinal bleeding (e.g., hemorrhoidal bleeding)
  • Therapy
    • Endoscopic hemostasis during colonoscopy (epinephrine injection, thermal coagulation, ligation)
    • Angiography with vessel embolization
    • In case of severe bleeding or recurrent disease: segmental colectomy
• Abscess
  • Peridiverticular localization; causes similar symptoms to acute diverticulitis
  • Suspect an abscess in patients with persistent fever and abdominal pain despite antibiotic treatment
• Perforation: symptoms of acute abdomen caused by
  • Rupture of an inflamed diverticulum → free communication with the peritoneum, generalized fecal peritonitis
  • Rupture of a diverticular abscess → generalized purulent peritonitis
• Fistulas
  • Colovesical (most common)
    • Symptoms: pneumaturia and fecaluria; may cause recurring urinary tract infections, including urosepsis
    • Diagnosis: CT with oral contrast
      • Localized thickening of colon and bladder
      • Air or contrast material in the bladder
    • Treatment
      • Primary anastomosis
      • Antibiotics if surgery is not possible
  • Other forms: colovaginal, coloenteric, colocutaneous
• Intestinal obstruction
  • Causes: inflammatory swelling, compression through abscesses, ileus caused by localized irritation
  • Symptoms: abdominal pain and distension, constipation, nausea, vomiting, acute abdomen

References:^[5][8][9]

We list the most important complications. The selection is not exhaustive.