Diverticular disease

Diverticular disease encompasses a set of colonic pathologies that result from abnormal outpouchings of the colonic mucosa (diverticula). It includes diverticulosis (noninflamed diverticula) and diverticulitis (inflamed diverticula). Colonic diverticula develop due to a combination of chronically elevated intraluminal pressures due to chronic constipation (e.g., due to low-fiber diets, lack of physical exercise) and age-related weakening of connective tissue. This causes the colonic mucosa to herniate through areas of weakness in the muscular layer. The sigmoid colon is most commonly involved. Incidence increases with age, and approx. 50% of individuals are affected by the 7^th decade of life. Diverticulosis is typically asymptomatic but may manifest with lower gastrointestinal bleeding, altered bowel habits, and/or abdominal pain. Diverticulitis may remain localized (mild uncomplicated diverticulitis) or progress, resulting in complications such as abscess or perforation (complicated diverticulitis). Diverticulitis typically manifests with fever and left lower quadrant abdominal pain (as the sigmoid colon is most commonly involved). Colonoscopy is the diagnostic modality of choice for symptomatic diverticulosis but is contraindicated if acute diverticulitis is suspected. Abdominal CT scan with IV contrast is preferred in suspected acute diverticulitis. Uncomplicated diverticulitis usually responds to conservative management with bowel rest and analgesics; oral broad-spectrum antibiotics are reserved for patients at high risk of complications. In complicated diverticulitis, management consists of parenteral antibiotics, treatment of any complications, and, in some cases, emergency colonic resection. Once the acute phase has resolved, a colonoscopy is indicated to rule out malignancy. Elective colectomy is recommended for all patients with complicated diverticulitis that is managed conservatively. The procedure is not routinely indicated for uncomplicated diverticulitis.

• Diverticula: blind pouches that protrude from the gastrointestinal wall and communicate with the lumen
  • True diverticulum; : a type of diverticulum that affects all layers of the intestinal wall.
    • Rare (except Meckel diverticulum )
    • Typically congenital
    • Most commonly occur in the cecum
    • Occur less commonly in the colon
  • False diverticulum or pseudodiverticulum: type of diverticulum that involves only the mucosa and submucosa and does not contain muscular layer or adventitia.
    • Most common type of gastrointestinal diverticula
    • Typically acquired
• Diverticulosis: the presence of multiple colonic diverticula without evidence of infection ^[1]
• Diverticulitis: inflammation or infection of colonic diverticula

• In the US, ∼ 50% of individuals > 60 years have diverticulosis ^[2]
• More common in high-income countries due to the higher prevalence of a high-fat, low-fiber diet

Epidemiological data refers to the US, unless otherwise specified.

• Caused mainly by lifestyle and environmental factors
  • Diet (low-fiber, rich in fat and red meat)
  • Obesity
  • Low physical activity
  • Increasing age
  • Smoking
• Other causes: genetic factors
  • Connective tissue disorders (e.g., Marfan syndrome, Ehler-Danlos syndrome) ^[1][3]
  • Autosomal dominant polycystic kidney disease

References:^[4][5]

• Diverticulosis: The formation of diverticula is considered multifactorial.
  • Increased intraluminal pressure; , e.g., due to chronic constipation
  • Weakness of the intestinal wall
    • Age-related loss of elasticity of the connective tissue
    • Physiological gaps in the intestinal wall, which occur where blood vessels penetrate, predispose to protrusion and herniation of intestinal mucosa and submucosa.
  • Localized particularly in the sigmoid colon
• Diverticulitis
  • Most commonly: chronic inflammation and increased intraluminal pressure → erosion of diverticula wall → inflammation and bacterial translocation
  • Rarely: stool becomes lodged in diverticula → obstruction of intestinal lumen → inflammation

References:^[6]

Diverticulosis

• Usually asymptomatic
• May manifest with abdominal discomfort; or pain, especially if associated 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 (constipation in ∼ 50% of cases and diarrhea in 25–35% of cases)
• Nausea and vomiting (caused by bowel obstruction or ileus)
• Acute abdomen: indicates possible perforation and peritonitis
• ↑ Urinary urgency and frequency (in ∼ 15% of cases)

In elderly or immunocompromised patients, clinical symptoms may only be mild.

References:^[6][7]

Diverticulosis

Asymptomatic diverticulosis ^[8]

• Typically an incidental diagnosis
• No workup required

Symptomatic diverticulosis ^{[9][10][11][12][13]}

• Colonoscopy: diagnostic modality of choice for suspected symptomatic diverticulosis ^[12]
  • Indications
    • Lower GI bleed
    • Recurrent abdominal pain and/or diarrhea
    • Concern for underlying malignancy ^[13]
  • Findings: well-defined outpouching from the colonic wall
  • Avoid if acute diverticulitis is suspected.
  • Biopsy and histological analysis can be performed, if necessary

• Double-contrast barium enema: highly sensitive test to detect diverticulosis but not commonly performed ^[9]
  • Consider in the workup of the following: ^[10]
    • Recurrent LLQ pain without signs of acute inflammation
    • Altered bowel habits
    • Lower GI bleed in a hemodynamically stable patient if colonoscopy cannot be performed
  • Contraindications: suspected diverticulitis or perforated diverticulum ^[13][11]
  • Findings: outpouching of the colonic wall of variable size

• Abdominal ultrasound
  • Indications: may be performed as part of the workup for nonspecific LLQ pain ^[11]
  • Findings: hypoechoic or anechoic outpouching from the colonic wall ^[13]

Colonoscopy is the diagnostic modality of choice for symptomatic diverticulosis.

Diverticulitis ^[14]

Suspect acute diverticulitis in adult patients presenting with LLQ pain, fever, and leukocytosis. The diagnosis is confirmed with imaging, preferably with IV contrast-enhanced CT scan. Once the acute phase has resolved, a colonoscopy should be performed to rule out malignancy. Colonoscopy is contraindicated in the acute phase because of the risk of perforation.

Laboratory studies ^[14][1][15]

• Routine tests
  • CBC: leukocytosis; , possible anemia
  • BMP: electrolyte abnormalities, ↑ BUN, ↑ creatinine
  • CRP: ↑ CRP
  • FOBT: positive in patients with diverticular bleeding
• Tests to rule out common differential diagnoses
  • Urinalysis: to rule out UTI and nephrolithiasis
  • Urine or serum β-hCG: to rule out pregnancy, including complications of ectopic pregnancy in all women of reproductive age
  • Stool microscopy: to rule out gastroenteritis
  • See “diagnostics” in acute abdomen for further information.

Imaging ^{[11][14][15][16][17][18]}

• CT abdomen and pelvis with IV contrast ^[11]
  • Indications
    • Preferred initial imaging modality for suspected diverticulitis ^[11]
    • Staging the severity of diverticulitis (see modified Hinchey classification of diverticulitis)
  • Supportive findings
    • Colonic outpouching
    • Signs of inflammation
      • Bowel wall thickening > 3 mm
      • Peridiverticular mesenteric fat stranding
    • Complications may also be identified
      • Peridiverticular abscess: hypodense collections with peripheral contrast enhancement
      • Diverticular perforation: pneumoperitoneum
      • Intestinal obstruction: dilated intestinal loops with multiple air-fluid levels

• MRI abdomen and pelvis (without and with IV contrast)
  • Indications: suspected diverticulitis in patients with contraindications to CT ^[11]
  • Findings: similar to those on CT scan
• Ultrasound abdomen
  • Indications: an alternative to MRI in patients with contraindications to CT
  • Supportive findings: diverticula with surrounding inflammation (hyperechoic), abscess formation (detectable fluid), bowel wall thickening

• Abdominal x-ray ^[15]
  • Not useful in diagnosing uncomplicated diverticulitis
  • Indications
    • Suspected perforation or bowel obstruction
    • May be performed as part of the routine workup for acute abdominal pain
  • Findings that may be seen in complicated diverticulitis include
    • Bowel perforation: pneumoperitoneum
    • Bowel obstruction: dilated bowel loops and multiple air-fluid levels
• Screening colonoscopy ^{[19][17][14][15]}
  • Recommended 6–8 weeks after the resolution of the acute episode to assess the extent of diverticulitis and rule out malignancy ^[14]
  • Colonoscopy is contraindicated during an acute episode because of the increased risk of perforation.
  • Not required if a recent evaluation of the colon has been performed ^[19]

Avoid colonoscopy during the acute phase of diverticulitis because of the risk of perforation!

Classification of diverticulitis

• To choose the best treatment approach and determine the prognosis, identifying the stage of acute diverticulitis is recommended. ^[15]
  • Uncomplicated diverticulitis: localized inflammation of a colonic diverticulum with no evidence of complications (i.e., Modified Hinchey stage 0 and stage Ia)
  • Complicated diverticulitis: inflammation of a colonic diverticulum associated with complications such as perforation, abscess, fecal peritonitis, bowel obstruction, or fistula formation (i.e., Modified Hinchey stages Ib–IV) ^[14]
• The modified Hinchey classification is based on CT findings and is the most commonly used classification.

Modified Hinchey classification of diverticulitis [17][18][20]
Stage		CT findings	Interpretation
Inflammation	0	Colonic diverticula with or without mural thickening of the adjacent colon	Clinically mild diverticulitis
	Ia	Colonic diverticula PLUS mural thickening of the adjacent colon PLUS evidence of inflammation within the pericolic fat	Diverticulitis with localized pericolic phlegmonous inflammation
Abscess	Ib	Stage Ia findings PLUS pericolic abscess	Diverticulitis with local abscess formation
	II	Stage Ia findings PLUS an abscess distant to the primary infection	Diverticulitis with distant abscess formation
Perforation	III	Pneumoperitoneum PLUS local/generalized free fluid WITHOUT evidence of communication between the perforated segment and peritoneal cavity	Perforated diverticulitis with purulent peritonitis
	IV	Pneumoperitoneum PLUS local/generalized free fluid WITH evidence of communication between the perforated segment and peritoneal cavity	Perforated diverticulitis with fecal peritonitis

• Differential diagnoses of uncomplicated acute diverticulitis
  • Crohn disease, ulcerative colitis
  • Colorectal cancer
  • Intestinal ischemia (ischemic colitis)
  • Acute appendicitis
  • Ileus , colonic obstruction
  • Ectopic pregnancy
  • Ovarian torsion
  • Ovarian cancer
  • Inguinal hernia
  • Renal colic
  • Urinary tract infection
• Differential diagnoses of perforated diverticulitis: See gastrointestinal perforation.
• See differential diagnoses of acute abdomen for a more comprehensive list.

The differential diagnoses listed here are not exhaustive.

Diverticulosis

• Asymptomatic diverticulosis
  • No treatment can reverse the growth of existing diverticula.
  • The goal is the prevention of progression (see “Prevention of recurrence and disease progression” below).
• Symptomatic diverticulosis: see “Treatment” in GI bleeding

Diverticulitis ^[18][13][21]

Approach

• Uncomplicated diverticulitis (Modified Hinchey stage 0 and stage Ia)
  • Conservative management ^[15][18]
  • Consider broad-spectrum oral antibiotics (e.g., ciprofloxacin PLUS metronidazole) in select patient groups.
• Complicated diverticulitis (Modified Hinchey stages Ib–IV)
  • Inpatient management with broad-spectrum IV antibiotics is recommended.
  • CT-guided percutaneous drainage for abscesses > 4 cm
  • Emergency colectomy in patients with generalized peritonitis

Acute management

Uncomplicated diverticulitis ^[18][21][15]

• Antibiotic therapy: Not routinely recommended ^[17][19][22]
  • Indications ^[17][22][23]
    • Signs of generalized infection (e.g., fever)
    • Pregnancy
    • Immunosuppression
    • Comorbidities
  • Consider one of the following commonly used broad-spectrum oral antibiotics ^[22][23]
    • Metronidazole ^[22]
      • PLUS one of the following
        • Ciprofloxacin ^[22]
        • Levofloxacin ^[22]
        • Trimethoprim-sulfamethoxazole ^[22]
    • Amoxicillin-clavulanate ^[22]
    • Moxifloxacin ^[22]
  • See also empiric antibiotic therapy for intra-abdominal infections
  • Duration of antibiotic therapy: 4–7 days ^[17]
• Supportive care
  • Relative bowel rest: clear liquid diet until improvement of symptoms
  • Analgesics as needed (see acute pain management)
  • Antiemetics as needed
• Additional considerations
  • Outpatient treatment
  • Follow-up in 2–3 days for evaluation of progression (earlier if symptoms worsen)
    • No improvement: Consider inpatient management; repeat imaging to evaluate for complications.
  • Screening colonoscopy once symptoms have resolved.
  • Consider elective colectomy for recurrent uncomplicated diverticulitis.
  • GI consultation for patients with frequent, recurrent episodes or chronic symptoms ^[22]

Complicated diverticulitis ^{[18][17][19][21] [22]}

• Antibiotic therapy: broad-spectrum IV antibiotics are routinely recommended (see empiric antibiotic therapy for intra-abdominal infections)
• Supportive care
  • Complete bowel rest (NPO)
  • IV fluids (see IV fluid therapy)
  • Analgesics as needed (see acute pain management)
  • Antiemetics as needed (see antiemetics)
• Management of complications
  • Abscess ^[18][24][15]
    • Size < 4 cm: trial of conservative management with IV antibiotics
      • Signs of improvement in 48–72 hours: Start enteral feeds; consider switching to oral antibiotics.
      • No signs of improvement in 48 hours: Repeat imaging and consider percutaneous drainage.
    • Size ≥ 4 cm
      • Ultrasound- or CT-guided percutaneous drainage
      • Consider laparoscopic or open surgical drainage if percutaneous drainage is not feasible.
      • Continue IV antibiotic therapy.
      • Send aspirate or pus for cultures and tailor antibiotic treatment accordingly.
  • Perforation with generalized peritonitis; (i.e., clinical signs of diffuse peritonitis or modified Hinchey stage III and stage IV on imaging): emergency surgery ^[18][17]
    • Hemodynamically stable patients: laparoscopic or open colectomy and primary anastomosis with/without a temporary diverting stoma
    • Critically ill patients: Hartmann procedure
  • Bowel obstruction
• Additional considerations
  • Inpatient treatment with surgery and/or IR consultation
  • Screening colonoscopy once symptoms have resolved
  • Consider elective colectomy if not performed during admission.

Subsequent management

Elective colectomy ^{[14][19][15][18]}

• Indications
  • Routinely recommended 6–8 weeks after resolution of complicated diverticulitis
  • Select groups of patients after resolution of uncomplicated diverticulitis, including: ^[15][17][18]
    • Patients at high risk of recurrence with complications ^[15]
    • Patients with persistent abdominal symptoms after resolution of an acute episode
  • Chronic complications of diverticulitis (e.g., fistula, colonic strictures)
• Procedure: laparoscopic or open colectomy ^[17][15]

Prevention of recurrence and disease progression ^[19][17]

• High-fiber diet ^[19][25]
• Fluid hydration
• Weight reduction
• Vigorous physical activity
• Cessation of smoking
• Avoid nonaspirin NSAID use, if possible.

• Diverticular bleeding ^[20][26]
  • Epidemiology
    • Diverticulosis is the most common cause of lower GI bleeding in adults.
    • Occurs in ∼ 5% of individuals with diverticulosis
  • Etiology: 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)
  • Treatment
    • Endoscopic hemostasis during colonoscopy (e.g., epinephrine injection, thermal coagulation, ligation)
    • Angiography with vessel embolization
• Fistulas ^[27]
  • Colovesical (most common)
    • Symptoms
      • Pneumaturia and fecaluria
      • May cause recurring urinary tract infections, including urosepsis
    • Diagnosis: CT with oral contrast
      • Localized thickening of the colon and bladder
      • Air or contrast material in the bladder
    • Treatment
      • Resection and primary anastomosis
      • Antibiotics if surgery is not possible
  • Other forms: colovaginal, coloenteric, colocutaneous
• Inflammation (diverticulitis)
• Abscess
  • Peridiverticular localization
  • Causes symptoms similar to those of 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
• Intestinal obstruction
  • Causes
    • Narrowing due to inflammatory swelling
    • Compression through abscesses
    • Ileus caused by localized irritation
  • Symptoms
    • Abdominal pain and distention
    • Constipation
    • Nausea, vomiting
    • Acute abdomen

References:^[7][26][27]

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