Bowel Diverticulosis

Abstract

Colonic diverticulosis is the presence of outpouchings of the intestinal walls in the colon. It remains without symptoms in most individuals, but about 25% of individuals will develop symptoms of diverticulosis at some point in time, and this is termed as colonic diverticular disease. The severity of this illness is variable and ranges from symptomatic uncomplicated diverticular disease (SUDD) to symptomatic disease with complications such as inflammation of these outpouchings or occasional bleeding. The diagnosis of diverticular disease depends mainly on radiological studies, such as computed tomography (CT) abdomen pelvis and magnetic resonance imaging (MRI) scan. The management is a multilevel approach that focuses on lifestyle modifications and pharmacotherapies to provide symptomatic relief and reduce progression risks into complicated diseases. Rarely, endoscopic interventions may be needed in some complicated cases.

1. Introduction

Diverticulosis is a prevalent gastrointestinal disorder characterized by the development of small pouches, called diverticula, in the colon’s lining.

These pouches typically develop in areas of the colon that are considered weak and most susceptible to intraluminal pressure such as where bleed vessels penetrate the muscular layer of the colon wall.

While many individuals with diverticulosis remain with no symptoms, complications such as diverticulitis, inflammation, or infection of the diverticula can occur.

This comprehensive review explores the epidemiology, risk factors, pathogenesis, diagnosis, management, and potential complications of diverticulosis.

2. Epidemiology and risk factors

Diverticulosis is common, with its prevalence increasing with age. In Western countries including Western Europe, United States, and Australia, it affects approximately 35% of individuals over the age of 50. The incidence is noted to be lower in Asian and African populations, but it has been rising in recent years as well. Diverticulosis is more common in industrialized or developed countries, and this may be due to dietary and lifestyle factors. It is also worth noting that the incidence of diverticulosis, generally speaking, is higher in the left side of the colon in Western countries as compared to the right side in Asian countries, and this skewed distribution is probably related to differences in colonic anatomy and physiology [1].

Several factors contribute to the development of diverticulosis, including age, genetics, and lifestyle choices.

Studies have shown that advancing age is strongly associated with an increased risk. Bowel diverticulosis exhibits a substantial prevalence, with a notable increase in occurrence among older individuals. A study in 2020 [2] reported a prevalence of approximately 42% among individuals aged 40–59 years and an increased prevalence of 80% among those aged 60 years and above in the United States.

Other risk factors include a low-fiber diet, obesity, sedentary lifestyle, smoking, and the use of nonsteroidal anti-inflammatory drugs (NSAIDs).

Regarding dietary factors, it has been found that a diet low in fiber and high in red meat and processed foods increases the risk of developing diverticular disease [3]. Conversely, higher intake of dietary fiber, particularly from fruits and vegetables, has been associated with a reduced risk of diverticulosis.

Studies have also shown that environmental factors in lifestyle and diet interact with genetic factors in predisposed individuals to contribute to the overall risk of developing the disease.

Research on the genetic predisposition to diverticulosis is still evolving, but recent studies have provided insights into potential genetic influences. Specific genetic variants associated with diverticulosis susceptibility have been identified, suggesting a role for genetic factors in the development of this condition [4].

3. Pathogenesis

The exact cause of diverticulosis is not fully understood, but it is believed to be multifactorial. The condition usually arises from a combination of structural, mechanical, and dietary factors that affect the integrity of the bowel wall.

The primary factor is thought to be increased colonic pressure due to a low-fiber diet, leading to muscular hypertrophy and weakness in the colon wall. This increased intraluminal pressure exerted during periods of constipation or straining prior to bowel movements causes the formation of pouches at sites of structural weakness, typically where blood vessels penetrate the muscular layer of colonic wall (Figure 1). In the diverticulosis of descending colon, the mucosa and submucosa protrude away from the colonic lumen forming (“pseudo-diverticula”), while in the diverticulosis of the ascending colon, all colonic layers protrude forming (“real diverticula”) [5].

Figure 1.

Colonic diverticula form when mucosa and submucosa herniate through the envelope that surrounds the vasa recta. Diverticular hemorrhage is arterial bleeding into an uninflamed diverticulum. Acute diverticulitis is complicated diverticula by inflammation.

The role of the microbiota in diverticulosis and diverticular disease is unknown at this time as there is no proven evidence of microbial imbalance in colonic diverticula to suggest that the microbiota contributes to the pathogenesis of asymptomatic diverticulosis, symptomatic uncomplicated diverticular disease, or complicated diverticular disease [6].

4. Classification of diverticular disorders

The classification of diverticulosis of the bowel is based on the presence of symptoms. In symptomatic illness, it is further subclassified based on the type of complication associated with that illness (Figure 2) and as follows.

Figure 2.

Classification of diverticulosis spectrum disorders.

4.1 Asymptomatic diverticulosis

This is often found incidentally in those undergoing certain radiological studies for other reasons [7]. However, no medical treatments or interventions are necessary here, and no additional follow-up is needed as there are unclear benefits.

4.2 Acute and chronic diverticulitis

This type of Inflammatory complication may present acutely or chronically in up to 25% of individuals with preexistent diverticulosis. The pathophysiology involves obstruction of the diverticular sac by feces, causing mucosal irritation leading to inflammation, edema, congestion, and further obstruction. Diverticulitis may be subclassified into complicated and uncomplicated. These complications include fistulas, abscesses, bowel obstruction and/or perforation of the gut. An important consideration in managing diverticulitis is the hospitalization decisions. The factors incorporated here include failure of clinical improvement and tolerating oral intake, certain comorbidities like heart failure or immunosuppression status, and the mentioned complications.

4.3 Symptomatic uncomplicated diverticular disease

This is basically presenting as chronic mild abdominal pain with no inflammation-related signs or symptoms. There may be an overlap between SUDD and irritable bowel syndrome (IBS) [8]. It is still unclear whether these two disorders are under the same spectrum representing different severities or are they different as both present similarly chronic episodic abdominal pain that seems more functional in origin with IBS rather than structural in SUDD.

4.4 Segmental colitis associated with diverticulosis

It is worth noting that this one does not necessarily involve the diverticula so there is some segmental involvement and some sparing of adjacent segments.

5. Diagnosis of diverticulosis and diverticulitis

Diagnosing diverticulosis involves a comprehensive assessment, including medical history, physical examination, and diagnostic tests. Imaging modalities such as computed tomography (CT) scans and barium enemas help identify diverticula and assess their complications (Figure 3).

Figure 3.

Radiological appearance of early intramural diverticulosis in a 52-year-old man. A. Barium enema examination shows the serrated margins of the sigmoid loop caused by thorn-like mucosal protrusions into the wall. B. Magnified radiograph of the descending colon demonstrates several 1–2 mm diverticula (arrows). Source: [10].

Other than the presenting symptoms, the medical history should focus on the individual risk factors for gastrointestinal diseases. The age of the patient, along with social and dietary histories, are more relevant here. During the physical examination, physicians may look for signs of rectal bleeding.

Colonoscopy allows direct visualization of diverticula and the detection of other lesions that are not uncommon to be seen simultaneously.

There are emerging technologies for the diagnosis of diverticulosis, and these may include virtual colonoscopy, also known as computed tomography colonography (CTC). This noninvasive imaging technique uses CT to create a 3D reconstruction of the colon. It offers advantages such as reduced invasiveness, no need for sedation, and shorter procedure time. CTC has shown promise in detecting diverticula and associated complications [9]. Another technology is wireless capsule endoscopy, which involves swallowing a small camera capsule that captures images as it traverses the digestive tract. Although primarily used for small bowel evaluation, recent studies have explored its potential application for assessing the colon, including the detection of diverticula. Further research is needed to establish its diagnostic utility in diverticulosis. The last one is the use of Biomarkers [10] and Genetic Testing; research is underway to identify potential biomarkers and genetic markers associated with diverticulosis. These markers may aid in early detection, risk stratification, and personalized management of the condition. While still in the early stages, these emerging technologies hold promise for future diagnostic advancements.

For acute diverticulitis, there is acute left lower quadrant abdominal pain, fever, and usually leukocytosis in almost all cases. CT scan findings can also be suggestive but should not be given top priority over the clinical picture in making a diagnosis (Figure 4).

Figure 4.

As above, note comparison of three different modalities of imaging including ultrasonography, computerized tomography, and magnetic resonance imaging scans.

Ultrasound may be used as an initial tool for those who want to avoid radiation; however, American College of Physicians suggests that clinicians use abdominal CT scans when there is reasonable suspicion of diverticulitis, and this is considered low-certainty evidence [11].

Magnetic resonance imaging (MRI) is a nonionizing imaging alternative to CT that can be considered for diagnosis of diverticulitis, especially in pregnant women and those who refuse CT scans; however, it has its own limitations as well such as the presence of metals implants in joints, inner ears that makes it risky to use and there are financial limitations.

There are no current indications for colonoscopy in acute diverticulitis. However, it should be performed in most patients after acute diverticulitis episode resolution for reasons that may include ruling out colonic neoplasms.

6. The management of diverticulosis and complications

General Guidelines

1. Dietary Modifications:

   Increasing dietary fiber intake is crucial for managing diverticulosis. Fiber adds bulk to stool, promotes regular bowel movements, and reduces the risk of diverticula becoming inflamed. Whole grains, fruits, vegetables, and legumes are excellent sources of fiber. Maintaining adequate hydration is often advised for optimal bowel function and stool consistency.

2. Lifestyle Modifications:

   Engaging in regular physical activity helps maintain bowel regularity and reduces the risk of complications. Maintaining a healthy weight is crucial, as obesity has been associated with an increased risk of diverticulosis.

3. Pharmacotherapy:

   Bulk-forming agents: Fiber supplements such as psyllium can increase stool bulk and ease bowel movements but are associated with side effects like bloating and flatulence. Antispasmodics like dicyclomine may be prescribed to relieve abdominal cramping and discomfort associated with diverticulosis.

   On the other hand, there are medications to avoid. The American Gastroenterology Association guidelines recommend avoiding nonaspirin NSAIDs (but not avoiding therapeutic aspirin) in patients after acute diverticulitis; however, it is a very low quality of evidence, given that it is derived from observational data [12].

   The newest American Gastroenterology Association (AGA) guidelines suggest against the use of rifaximin as an agent to reduce diverticulitis recurrence as there is no scientific proof of its efficacy, and the same applies to mesalamine.

   Recurrent diverticulitis can cause changes in microbial contents of the bowels, but relevant data is still lacking at this time. A meta-analysis conducted by Lahner et al. [13] examined 11 studies in which some probiotics were used in the treatment of symptomatic diverticular disease. Upon examination of an overall pool of 764 patients, there seems to be some drop in the frequency of abdominal symptoms with some Lactobacilli use. Data on preventive roles are still lacking; however, the 2015 AGA guidelines recommend against the use of probiotics after diverticulitis episodes.

Management of Complications:

1. Diverticular bleeding

Colonic diverticular disease sometimes presents with bleeding, which is the most common cause of lower gastrointestinal bleeding (LGIB), colonoscopy is done here to identify bleeding locations and to do onsite hemostasis.

Unfortunately, the bleeding detection rate is relatively low, and access to the bleeding sites is not always achievable. In patients with suspected diverticular bleeding, colonoscopy is generally indicated: (a) Electively, when bleeding has stopped spontaneously. This approach also rules out vascular ectasia or colonic neoplasia. (b) As an urgent intervention in treating diverticular bleeding. (c) As a last resort in patients with recurrent episodes of LGIB, computerized tomography angiography was nondiagnostic.

When endoscopic methods fail to control bleeding or in cases of severe hemorrhage, surgical interventions play a role in managing diverticular bleeding, and these surgical approaches include segmental resection, which involves the removal of the affected portion of the colon, which includes the diverticula responsible for the bleeding. This procedure aims to eliminate the source of bleeding and prevent future episodes. The remaining healthy ends of the colon are then reconnected [14]. Another approach is Hartmann’s Procedure, which involves the removal of the affected portion of the colon, creating an end colostomy, and closing the rectal stump. In a subsequent surgery, the colostomy can be reversed [15]. Another approach is Angiographic Embolization, which is a minimally invasive technique that involves the insertion of a catheter into the blood vessels supplying the bleeding diverticula. Through the catheter, embolic agents, such as coils or particles, are delivered to occlude the vessels and stop the bleeding [16]. Angiographic embolization can be an effective alternative to surgery, particularly in cases where the patient is not a suitable candidate for surgery or when a less invasive approach is desired. An adjustment of the latter technique is transarterial embolization, which involves the delivery of embolic agents to the bleeding vessels. This technique specifically targets the branches of the superior mesenteric artery that supply the bleeding diverticula [17].

1. Diverticulitis:

Mild cases can often be managed with rest, a clear liquid diet, and oral antibiotics covering anaerobes and gram-negative rods, such as ciprofloxacin and metronidazole or amoxicillin clavulanic acid continued for seven to 10 days is the usual treatment.

Patients are expected to improve within 48 to 72 hours, at which time the diet may be advanced cautiously.

Severe cases defined by picture of sepsis, immunocompromised or elderly patients above 65-year-old or those with significant comorbidities will need hospitalization, intravenous antibiotics like metronidazole or clindamycin, and third-generation cephalosporins like ceftriaxone, and in some cases, surgical intervention may be necessary to treat complicated diverticulitis or recurrent episodes.

1. Abscesses and Perforation:

   In situations when fever, leukocytosis, or both persist despite use of antibiotic trial then a peri-diverticular abscess should be suspected, and an abdominal exam may or may not show a palpable tender mass; then comes the CT scan findings suggesting a collection or collections.

   In such situations, percutaneous drainage guided by imaging like CT scan is the primary treatment for abscesses associated with diverticulitis, and this procedure is indicated mainly for abscesses that may have enteric communication, more than 3 cm in size, multi-loculated in nature, especially in those who fail initial medical treatment [18].

   Colonic perforation is rare; however, if it happens, it is usually followed by peritonitis and unfortunately, carries a considerably high mortality rate, as high as 35 percent, and requires surgical urgency. Surgical interventions with a partial colectomy may be required to manage perforations and prevent further complications.

2. Obstruction and Fistula Formation:

   Colo-vesical fistulas usually need surgical corrections. Fistulas involving the bladder are more common in men; as in women, the uterus is anatomically located between the colon and the bladder.

   Patients with this complication present with urinary tract infection, pneumaturia, and fecaluria. Abdomen computed tomography (CT) scan with contrast may show the diverticula in the colonic walls, fistulae tracks, or contrast leaking in the bladder or air in bladder, suggesting this type of complication.

   Surgical repair is typically required for fistulas, abnormal connections between the colon and other organs or structures.

   Bowel obstruction is generally self-limited and responds to conservative therapy. If persistent, obstruction of the colon can be treated by a variety of endoscopic and surgical techniques. Surgical intervention may be necessary to address bowel obstructions caused by strictures or adhesions resulting from recurrent diverticulitis episodes.

7. Summary and conclusion

Diverticulosis is a prevalent gastrointestinal condition that requires a comprehensive approach to diagnosing, managing, and recognizing potential complications. Understanding the epidemiology, risk factors, pathogenesis, and appropriate management strategies allows for early detection, prevention of complications, and improved patient outcomes. By adopting dietary modifications, lifestyle changes, and prompt medical attention, individuals with diverticulosis can effectively manage their condition and enhance their overall well-being. Those with diverticulitis should be treated medically when indicated and will need regular follow-up care by a designated gastroenterologist to reduce risks of potential future complications and recurrence.

Acknowledgments

We would like to thank Jamaica Hospital for their resources used in preparation of this book chapter.

Conflict of interest

The authors declare no competing conflicts of interests in preparing this book chapter.