Overview
Definitions
Diverticulosis is the presence of multiple diverticula, which are sac-like protrusions of the bowel wall.
Diverticular disease is diverticulosis with associated symptoms.
Presentation of diverticular diseases
- Diverticulitis (inflammation of the diverticulum/diverticula)
- Complications: obstruction, fistula, perforation, abscess
- Diverticular bleeding
- Segmental colitis associated with diverticula (SCAD)
- Symptomatic uncomplicated diverticular disease (SUDD)
Diverticulosis: image showing the large bowel (sigmoid colon) with multiple diverticula
Image: “Large bowel (sigmoid colon)” by Haymanj. License: Public DomainEpidemiology
- Colonic type is the most common diverticulosis.
- Prevalence:
- Age-dependent:
- < 20% at the age of 40
- 60% by the age of 60
- Higher in countries with a Western diet
- Age-dependent:
- Distribution varies by race/ethnic origin:
- Overall, left-sided diverticulosis is most common in the United States.
- African Americans: higher percentage of right-sided disease than in whites
- Asians: Right colon is predominantly affected.
- About 4% of those with diverticulosis develop diverticulitis, with a 20% 5-year recurrence rate.
Risk factors
- Diet:
- Low fiber
- High fat
- Red meat
- Seeds and nuts are not risk factors.
- Obesity
- Physical inactivity
- Increased risk of complicated diverticular disease:
- Genetic disorders
- Marfan syndrome
- Ehlers-Danlos syndrome
- Scleroderma
- Smoking
- Genetic disorders
Pathophysiology
Diverticulosis
- Intraluminal pressure causes herniation of the mucosa and submucosa through weak areas in the colon wall.
- Diverticula occur in these weak spots (where vasa recta or nutrient vessels penetrate the muscular layer).
- Colonic diverticula are considered “false” diverticula or pseudodiverticula (does not contain all layers of the bowel wall) as they do not contain a muscular layer.
- Diverticulosis in most patients involves the sigmoid (most common site) and the descending colon.
Pathophysiology of the development of diverticulosis from a healthy colon.
Colonic diverticula form when mucosa and submucosa herniate through the envelope that surrounds the intramural vasa recta (nutrient vessels).
Diverticulitis
- Increased intraluminal pressure and/or thickened food particles contribute to the erosion of the diverticular wall.
- In a minority of diverticulosis cases, inflammation, focal ischemia and/or necrosis (diverticulitis) follow, with bacterial translocation and possible micro-/macroperforation.
Types of diverticulitis
Diverticulitis is often mild, with mesentery and pericolic fat walling off a small perforation. More extensive disease can lead to complications.
- Simple or uncomplicated diverticulitis:
- No associated complication(s)
- 85% of diverticulitis cases
- Complicated diverticulitis (can be acute or chronic):
- Diverticular abscess (most common)
- Obstruction
- Free perforation
- Fistula (frequently with the bladder)
- Diverticular stricture
Clinical Presentation
Diverticulosis
- Asymptomatic
- In majority of cases, detected incidentally on colonoscopy or barium enema
Diverticulitis
- Symptoms:
- Abdominal pain
- Constant
- Left lower quadrant (LLQ) or suprapubic most common
- Right lower quadrant if right-sided
- Urinary urgency (from bladder irritation)
- Constipation or diarrhea
- Fever, nausea/vomiting
- Abdominal pain
- Signs:
- Tender LLQ and suprapubic areas (right LQ if with right-sided diverticulitis)
- Local peritoneal irritation (rebound tenderness)
- Diffuse guarding and peritonitis suggest perforation.
- Fever and tachycardia usually suggest complicated disease.
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Diagnosis
Diverticulosis
- Patient is asymptomatic: no work-up
- Discovered incidentally after tests are done
- Diverticular disease: Tests depend on presenting symptoms and suspected disease.
Diverticulosis: colonoscopy showing diverticula in the colon
Image: “Diverticulum” by MAC 06. License: CC BY 4.0Diverticulitis
- History:
- LLQ or suprapubic pain
- Recurrent similar episodes of pain
- Laboratory studies:
- Elevated WBC count (with left shift)
- Elevated C-reactive protein
- Computed tomography (CT) scan:
- Test of choice
- Will show:
- Diverticula
- Colonic wall thickening (> 4 mm)
- Pericolonic fat stranding
- Microperforations (small gas bubbles next to the colon wall)
- If complications are present, findings include:
- Abscess: fluid collection(s) with necrotic debris or air-fluid levels
- Fistula: air collection noted within other organs
- Obstruction: dilated bowel loops
- Perforation: free air noted
- Ultrasound:
- Can show inflammation, bowel wall thickening, diverticula, abscess
- Operator-dependent and requires experience
- Rarely used in practice
- Magnetic resonance imaging (MRI):
- Similar findings to CT scan
- Can be used when CT is contraindicated
- Colonoscopy:
- Contraindicated during an acute episode of diverticulitis due to increased risk of perforation
- Recommended 6–8 weeks after resolution of the acute episode:
- To establish the extent of the disease
- To rule out other diagnoses (malignancy: found in 1.3% of simple diverticulitis and in 8% of complicated disease)
Imaging illustrating diverticulitis:
Image: “CT scan of perforated diverticulitis” by Hupfeld et al. License: CC BY 4.0
CT scan showing perforated diverticulitis (horizontal arrows) and free abdominal air (vertical arrows)Ultrasound and CT scan images of diverticulitis:
Image: “Inflamed diverticula” by University of Washington, Division of Emergency Medicine, Seattle, Washington. License: CC BY 4.0
Transabdominal sonographic view of the patient’s abdomen (left) and associated axial CT (right) revealing inflamed diverticula (arrow).
Related imaging findings of diverticulitis such as edematous diverticula with thickened hypoechoic walls and hyperechoic centers, and surrounding hyperechoic zones representing inflamed fat.Imaging illustrating diverticulitis: CT scan with oral contrast shows an inflamed right-sided cecal diverticulum (arrow).
Image: “Cecal diverticulitis” by Monika Sharma and Anjali Agrawal. License: CC BY 2.0
Management
Hinchey classification of severity of acute diverticulitis
- Based on radiographic features
- Helps direct surgical management of diverticulitis complications
Hinchey 1a | Phlegmon (localized) |
---|---|
Hinchey 1b | Pericolonic/mesenteric abscess |
Hinchey 2 | Pelvic abscess |
Hinchey 3 | Generalized purulent peritonitis |
Hinchey 4 | Generalized feculent peritonitis |
Medical management
- Outpatient (generally for Hinchey 1a)
- 7–10 day course of oral antibiotics
- Fluoroquinolones + metronidazole
- Amoxicillin-clavulanate
- Trimethoprim-sulfamethoxazole + metronidazole
- Diet modification (optional): 2–3 days of clear-liquid diet
- Reassess in 2–3 days.
- 7–10 day course of oral antibiotics
- Inpatient
- Criteria for admission:
- Complicated diverticulitis
- Microperforation on CT scan (Hinchey 1b)
- Sepsis
- Fever > 39°C (102.5°F)
- Significant leukocytosis
- Age > 70
- Immunosuppression
- Significant comorbidities
- Intolerance of oral intake
- Failure of outpatient treatment
- Intravenous antibiotics: broad-spectrum with enteric coverage
- Bowel rest/clear-liquid diet
- Pain management
- Repeat CT scan in 2–3 days if no improvement to evaluate for complications.
- Criteria for admission:
- Recovery (about 6–8 weeks): Perform colonoscopy to rule out colon cancer.
Surgery
Rationale:
- Immediate:
- Free perforation/peritonitis (Hinchey 3 and 4)
- Worsening clinical course despite medical management
- Delayed/elective (6–8 weeks after an acute attack):
- Recurrent attacks of diverticulitis (2 or more)
- After an initial attack for high-risk patients:
- Diabetes
- Immunosuppression
- Renal failure
- Collagen vascular disorders (e.g., lupus)
- Complicated diverticulitis initially managed with medical therapy
Procedures:
- Elective/delayed:
- Segmental colon resection with primary anastomosis
- Usually after a colonoscopy to rule out other diseases (e.g., cancer)
- Emergent/same admission:
- Primary anastomosis is at risk of leaking in the setting of inflammation/infection.
- Diversion of fecal stream from the anastomosis is needed until healed:
- Hartmann’s procedure (resection of involved colon segment with end colostomy): gold standard
- Resection of involved segment with primary anastomosis and diverting loop ileostomy: alternative
- Reversal of colostomy/ileostomy can be performed in 3–6 months.
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Complications of Diverticulitis
Diverticular abscess (Hinchey 2)
- Walled-off pus collection that forms adjacent to a ruptured diverticulum
- 17% of hospitalized patients with acute diverticulitis
- Management:
- Intravenous antibiotics (1st-line treatment)
- Radiologically guided percutaneous drainage: for abscess > 4 cm (if accessible)
- Surgery if patient does not improve with antibiotics/drainage
Imaging illustrating a sigmoid diverticulitis-related abscess: CT scan showing peri-colonic fluid collection with air-fluid level (green arrow) consistent with an abscess
Image: “Sigmoid diverticulitis” by Department of Surgery, Macerata Hospital, Macerata, Italy. License: CC BY 4.0Obstruction
- Can develop acutely with severe colon inflammation
- Usually resolves when inflammation subsides
- A stricture may develop after an acute phase (scarring from inflammation).
- Diverticular stricture:
- Difficult to differentiate from cancer
- Usually requires surgery
Perforation
- Free colonic perforation with uncontained leakage in the peritoneal cavity
- Hinchey grade 3 and 4
- Patients usually present with peritonitis, fever, and tachycardia.
- Requires emergent surgery (Hartmann’s procedure)
Fistula
- Fistulas can develop as inflammation in the colon wall erodes into the adjacent organs:
- Colovesical (to bladder; presents with pneumaturia/ fecaluria)
- Colovaginal/colouterine (foul-smelling/feculent vaginal discharge)
- Coloenteric (to small bowel)
- Colocutaneous (to the skin)
- Can be initially managed with antibiotics in a stable patient
- Rarely heal on their own
- Eventually require surgical resection of the fistulizing colon segment
Colovesical fistula:
Image: “Colovesical fistula” by Department of Radiology, Geneva University Hospital, Gabrielle-Perret-Gentil, 4, 1211, Geneva 4, Switzerland. License: CC BY 2.0
A: thickening of the wall of the bowel and bladder (black asterisk)
B and C: collection of contrast and air into the bladderDiverticulitis fistulizing to the umbilicus: the inflamed and macerated umbilicus and periumbilical skin with fecal material in the umbilical pit
Image: “Diverticulitis fistulizing to the umbilicus” by Second Department of Surgery, Democritus University of Thrace, Medical School, 68 100 Alexandroupolis, Greece. License: CC BY 3.0
Other Presentations of Diverticular Disease
Diverticular bleeding
- Most common source of lower gastrointestinal (GI) bleeding in adults
- Vasa recta (in the diverticulum), covered by mucosal layer only, are exposed to continuous injury from luminal contents.
- Vessel walls weaken from intimal and medial changes, predisposing to rupture and bleeding.
- 50%–90% occur on the right colon.
- Manifestations:
- Usually painless hematochezia
- Sometimes associated with cramping and bloating
- Blood from the left colon is bright red; from the right colon, blood is maroon/brown.
- Spontaneously stops in 75% of patients but with increased risk of rebleeding
- Diagnosis and management of lower GI bleeding:
- Workup commences once the patient is stable and resuscitation (for blood loss) is complete.
- Colonoscopy: test of choice as it is both diagnostic and therapeutic
- Imaging:
- Nuclear scintigraphy (tagged red blood cell scan): detects bleeding with rate of 0.1–0.5 mL/min
- CT angiography:
- Detects bleeding with rate of 0.3–0.5 mL/min
- Requires intravenous contrast and has radiation exposure
- Angiography:
- Requires active bleeding loss of 0.5–1 mL/min
- Therapeutic intervention with vasoconstrictors/embolization can be given (carries complication risks).
- Surgery if bleeding cannot be controlled
Illustration of diverticular hemorrhage:
Arterial bleeding can complicate diverticulosis, with vascular disease or structural weakness as likely contributing factors. The condtion is the most common source of lower gastrointestinal bleeding.
Diverticular bleeding:
Image: “Colonic diverticular bleeding” by Department of Gastroenterology and Hepatology, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan. License: CC BY 3.0
(a) colonoscopy view of diverticular bleeding in the hepatic flexure
(b) endoscopic treatment using hemoclips
Segmental colitis associated with diverticulosis
- Inflammation of the interdiverticular mucosa (not diverticula themselves)
- < 2% of cases with diverticulosis
- Pathogenesis is not exactly understood, but may be related to:
- Chronic mucosal inflammation from diverticular herniation
- Fecal stasis with resultant change in bacterial flora
- Ischemia from changes to mucosal microcirculation
- Manifestations:
- Lower or LLQ abdominal pain
- Chronic diarrhea and occasional hematochezia
- Diagnosis:
- Discovered incidentally on work-up of diarrhea, abdominal pain, and hematochezia
- CT scan: colonic wall thickening in segment with diverticulosis
- Colonoscopy: interdiverticular inflammation often in the sigmoid colon, sparing the rectum
- Management:
- Antibiotics: ciprofloxacin, metronidazole
- Other options: mesalamine, course of prednisone
Symptomatic uncomplicated diverticular disease
- Also known as “smoldering” diverticulitis
- Colonic wall thickening without obvious inflammation
- Suspected causes:
- Abnormal colonic motility
- Visceral hypersensitivity
- Manifestations:
- Abdominal pain without other signs of acute diverticulitis
- Constipation
- Diagnosis:
- Rule out other GI functional disorders (e.g., irritable bowel syndrome (IBS))
- Clinical findings:
- Pain in SUDD: more sustained (often > 24 hrs)
- Pain not relieved by bowel movement, unlike in IBS
- Tenderness located in the left iliac fossa
- CT scan and colonoscopy:
- Performed depending on symptoms, risk of cancer, and clinical status
- Absence of diverticula excludes SUDD.
- Management: high-fiber diet; rifaximin has been tried with success
Differential Diagnosis
- Colorectal cancer (CRC): a colonic neoplasm that often presents with rectal bleeding and colonic obstruction. Colorectal cancer sometimes can be associated with inflammation; can perforate and mimic complicated diverticulitis. Diagnosis is by colonoscopy with biopsy in a stable patient. In an emergent situation, the diagnosis is sometimes made during surgery.
- Inflammatory bowel disease (IBD): a family of autoimmune diseases that includes Crohn’s disease and ulcerative colitis. Acute presentation can be similar to diverticulitis (lower abdominal pain, diarrhea (sometimes bloody), and fever). Diagnosis is established by detailed history and colonoscopy with biopsies.
- Appendicitis: inflammation of the appendix. Main symptom is right lower quadrant pain. May be impossible to clinically distinguish right-sided diverticulitis from acute appendicitis as the symptoms are very similar. Diagnosis is established by CT scan or sometimes during surgery.
- Pelvic inflammatory disease: sexually transmitted infection of the internal reproductive organs in women. Presents with lower abdominal/pelvic pain, local peritonitis, and fever. Diagnosis is established by history, gynecologic exam, and pelvic ultrasound or CT scan.
References
- Camilleri, M., Sandler, R., Peery, A. (2019) Etiopathogenetic Mechanisms in Diverticular Disease of the Colon. Cellular and Molecular Gastroenterology and Hepatology Vol 9, Issue 1, P15-32; https://www.cmghjournal.org/article/S2352-345X(19)30095-5/fulltext
- Ghoulam, E., Clarrett, D., Marsicano, E. (2019) Diverticulitis. Medscape. Retrieved 8 Dec 2020, from https://emedicine.medscape.com/article/173388-overview
- Maconi, G. (2017). Diagnosis of symptomatic uncomplicated diverticular disease and the role of rifaximin in management. Acta Biomed 88(1): 25–32. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6166204/
- McQuaid K.R. (2021). Diverticular disease of the colon. Papadakis M.A., McPhee S.J., Rabow M.W. (Eds.). Current Medical Diagnosis & Treatment 2021. McGraw-Hill.
- Mizuki, A., Tatemichi, M., Nagata, H. (2018). Management of Diverticular Hemorrhage: Catching That Culprit Diverticulum Red-Handed! Inflamm Intest Dis. 3(2): 100–106. doi: 10.1159/000490387
- Pemberton J.H. (2019). Colonic diverticulosis and diverticular disease: Epidemiology, risk factors, and pathogenesis. UpToDate. Retrieved December 5, 2020, from https://www.uptodate.com/contents/colonic-diverticulosis-and-diverticular-disease-epidemiology-risk-factors-and-pathogenesis?search=diverticular%20disease&source=search_result&selectedTitle=1~98&usage_type=default&display_rank=1
- Pemberton J.H. (2019). Clinical manifestations and diagnosis of acute diverticulitis in adults. UpToDate. Retrieved December 5, 2020, from https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-acute-diverticulitis-in-adults?search=diverticular%20disease&source=search_result&selectedTitle=6~98&usage_type=default&display_rank=5
- Pemberton J.H. (2020). Acute colonic diverticulitis: Medical management. UpToDate. Retrieved December 6, 2020, from https://www.uptodate.com/contents/acute-colonic-diverticulitis-medical-management?search=diverticular%20disease&source=search_result&selectedTitle=8~98&usage_type=default&display_rank=7