Diverticulosis: Epidemiology and Development

• Diverticular disease of the colon has become a common and significant gastrointestinal disorder in Western countries.
• The first clear pathologic description was provided in 1849 by Jean Cruveilhier, with Ernst Graser later describing diverticulitis in 1899.

Epidemiology

• Diverticulosis epidemiology has evolved since its initial descriptions.
• Diverticulosis is now considered a costly and common gastrointestinal disorder in the Western world.
• Approximately two thirds of adults will develop diverticulosis by their ninth decade.
• Diverticulosis is frequently found during colonoscopies, as high as 42.8% of all procedures and 71.4% in patients over 80.
• Two primary factors influence the development of diverticulosis: age and geography
• Diverticulosis prevalence increases with age, ranging from less than 10% in those under 40 to around 66% in those 80 and older.
• It has been considered a disease of Western civilization, with higher rates in industrialized countries and lower rates in rural Africa and Asia.
• Those immigrating to Western countries from non-Western regions have shown increased rates of diverticular-related hospitalizations.
• Reports suggest that the prevalence of the disease is rising in non-Western countries like Israel, Japan, Kenya, Korea, Singapore, and Uganda.
• Diverticular disease is a significant contributor to healthcare utilization, accounting for over 2.7 million ambulatory visits in the USA in 2010.
• In 2012, hospital admissions for diverticulitis without hemorrhage numbered around 217,000, costing $2.2 billion.

Pathology

• Most colonic diverticula are actually pseudodiverticula, which involve the mucosa and submucosa herniating through the muscular coat of the colon.
• Diverticula develop in 4 distinct rows corresponding to the sites of penetration of the bowel wall by the major branches of the vasa recta.
• The number of diverticula can range from a solitary instance to hundreds.
• Diverticula typically measure 3 to 10 mm in diameter, but giant colonic diverticula can exceed 4 cm.
• Inverted diverticula can resemble polyps endoscopically but can be distinguished via their normal overlying mucosa and broad base and location within a diverticula bed.
• In Western countries, 90% of diverticulosis cases involve the left side of the colon and 75% to 85% of cases in Asian countries involve the opposite side.

Pathogenesis

• The pathogenesis of diverticulosis is complex and not completely understood.
• Research has been focusing on intrinsic anatomic features, age-related alterations in the colonic wall, motility issues, environmental variables, and heritable elements.

Colonic Wall Structure

• Longitudinal (taenia) and the circular muscle layers become thickened, with shortening of the taeniae and accordion-like pleating with diverticula
• Myochosis refers to this appearance.
• Elastin deposition inside the muscle fibers causes wall thickening, normal muscle cells show more than 200% increases in elastin deposition between cells.
• Shortening of the taenia and bunching of the circular muscle results from elastin deposition in a contracted form.
• Increased type III collagen has been noted in patients with diverticulosis, which shows collagen composition alterations may play role.
• Tissue inhibitor of metalloproteinases is overexpressed in colons with diverticula.
• Connective tissue integrity is underscored by increased prevalence among patients with Ehlers-Danlos syndrome, Marfan syndrome, and progressive systemic sclerosis.

Motility

• Early studies found higher luminal pressures in patients with diverticulosis, leading to the segmentation theory.
• Segmentation theory states colon contraction occurs at haustral folds causing the colon to act as a discrete "little bladders" that elevate pressure inside the colon.
• Hypersegmentation resulting from fiber deficiency could contribute to diverticula formation.
• Patients with symptomatic diverticular disease exhibit higher motility indices than asymptomatic individuals.
• Both magnitude and direction of motility are abnormal, and retropropagation of contractile waves in diverticular segments has been recorded.
• The level of ion transport is similar in the epithelial membrane.
• Quantity of enteric pacemaker cells (interstitial cells of Cajal) are lessened.
• Compared to controls, diverticular colons have demonstrated more excitatory cholinergic nerves and less non-adrenergic, non-cholinergic inhibitory nerve activity.
• Antagonists of cholinergic and tachykinin neurotransmitters greatly lessen contractility in diverticulosis-affected sigmoid colons.
• Substance P induces decreased circular muscle contractility in diverticular colons when compared to normal colons.

Environmental Facors

• Dietary fiber has had a dominant position in among environmental-influence theories on diverticulosis.
• Reduced transit times and stool weights result from low-fiber diets.
• Low-fiber diets also result in elevated intraluminal pressure, predisposing to diverticular herniation,
• Bulky stools are associated with reduced colonic contraction and lower wall pressures.
• A 28% drop reported between 1909 and 1975 in USA fiber content correlated decreased fiber with diverticular disease increase.
• Vegetarians with high-fiber diets have been observed to have a lower occurrence than non-vegetarians.
• AGA says benefit of a fiber-rich diet for patients with acute diverticulitis history is uncertain due to low-quality evidence.
• High red meat, refined grains, and high-fat dairy (Western diets) increases presence of diverticulosis and/or its complications.
• Other lifestyle and environmental factors include obesity, refined grains, smoking, physical inactivity, alcohol or vitamin D deficiency.
• In one Asian study, right-sided diverticular disease showed no association with fruit, vegetables or supplemental fiber, but a strong correlation to meat intake did show.

Heritable Factors

• Diverticular disease can be significantly influenced by heritable factors like sex, genetics, and ethnicity.
• The disease appears to be equally common in both men and women, with women potentially experiencing more diverticulitis episodes.
• Siblings were shown to have triple the odds of developing diverticular disease relative to the general population.
• Hereditable component of diverticular disease has been estimated at around 40%.
• Hospitalization for diverticulitis demonstrates that surgery is more prevalent in African Americans and less frequent in Hispanics.
• These data shows both environmental and and heritable components have a strong affect.

Asymptomatic Diverticulosis

• Approximately 80% of patients diagnosed show no symptoms.
• Asymptomatic diverticulosis are incidental findings during evaluations for other conditions with increase colonoscopy and CT scans,
• Asymptomatic diverticulosis has no clear requirement for specific therapy or follow-up.
• Consuming nuts, corn, popcorn or seeded fruit does not raise diverticulosis or complications risks and are safe.

Symptomatic Uncomplicated Diverticular Disease (SUDD)

• Some patients come to clinical attention because of diverticulosis and abdominal complaints.
• SUDD shows no evidence of complications of diverticular disease (diverticulitis and diverticular bleeding).
• SUDD true prevalence is undetermined due to overfocus on diverticulitis and hemorrhage.
• Clinical similarities between SUDD and IBS confound distinguishing the 2.
• Patients with SUDD usually have long-term, uneventful clinical progression and low rates of complications like IBS.
• Some data suggest that diverticula a late consequence of IBS; clinical features and prognosis is not different than non-diverticula patients.
• Study suggests patients IBS and diverticulosis patients both experience similar pain sensations.

Pathophysiology of SUDD

• Some have theorized it is often a late consequence of IBS.
• Similar symptoms is present whether one has diverticula or not.
• It can be the result of hypersensitivity, altered colonic motility, low-grade inflammation, or gut microbiota alterations.

Clinical Features of SUDD

• It can be difficult to determine if the symptoms are from diverticulosis.
• Patients can experience lower left quadrant abdominal pain that eating exacerbates.
• Abdominal fullness and mild tenderness in the LLQ is seen, with no frank rebound or guarding absent.

Diagnosis of SUDD

• Colonoscopies are primary evaluation to exclude neoplasia; CT colonography and barium enema are rarely used.
• Colonoscopies are safe when evaluating diverticulosis patients showing abdominal symptoms.
• Spasm, prior inflammation or confusion between openings makes it difficult for an endoscopist to to proceed.
• Use of a pediatric colonoscope is recommended when the adult cannot be passed through the sigmoid.
• Distending the lumen with water, by using a sigmoid floatation maneuver can facilitate colonoscopies
• Water-assisted may decreased discomfort and improve polyp detection.
• Diagnostic should be normal, though testing for fecal calprotectin levels can be used.

Treatment of SUDD

• These are often non-specific and have equally as good prognoses.
• Fiber has been common, yet this claim is not confirmed in various observational studies.
• 5-Aminosaliclyic may an effective option, based treatment that can treat underlying colonic areas.
• Additional trials are currently ongoing.
• Disturbances of intestinal microbiota may predispose some to SIBO.
• Specific data of microbiome divergence is not yet confirmed.
• Increased study is warranted here, but the microbiota can be an important future target for some candidates.
• Hypermotility of the colon in diverticulosis suggests anti-spasmodic or anti-cholinergic may increase symptoms, though such trials are limited.
• Glucagon may offer immediate alleviation since it causes muscle relaxation.
• Treatment commonly depends on the patient itself, since the disease is not always the target.

Diverticular disease of the colon is a common gastrointestinal disorder, especially in Western countries. It is frequently found during colonoscopies, with prevalence increasing with age. Age and geography are two primary factors influencing its development.