Left-sided Diverticulosis Research Articles

Diverticulosis morphology is associated with risk of diverticulitis.

The size, number and distribution of diverticula vary greatly in patients with diverticulosis. We aimed to study the association between the morphology of diverticulosis assessed on colonoscopy and the risk of diverticulitis. We performed a retrospective, case-control study of cases with a history of diverticulitis and controls with diverticulosis without diverticulitis matched on sex, age (within 5 years) and year of colonoscopy. Diverticulosis characteristics were obtained from endoscopy reports and were categorized according to severity, extent, number and size. We used conditional logistic regression on matched pairs to calculate the odds of diverticulitis among patients with diverticulosis according to differing morphologic characteristics. We identified 85 cases with computed tomography-documented diverticulitis and 85 matched controls with diverticulosis without a diagnosis of diverticulitis. In cases, 60% had left-sided only diverticulosis, 2% had right-sided only and 38% had both right and left-sided diverticulosis; whereas in controls, the distribution was 53%, 18% and 29%, respectively. Cases were more likely to have large diverticula [odds ratio (OR), 3.33; 95% confidence interval (CI), 1.30-8.56 for left colon only and 1.89, 95% CI, 0.78-4.57 for both right and left]. Similarly, when the severity of diverticulosis was compared between the groups, cases were more likely to have moderate or severe diverticulosis (OR, 3.44; 95% CI, 1.51-7.84 for moderate and OR, 8.87; 95% CI, 2.98-26.37 for severe). Diverticulitis cases were more likely to have large diverticula and severe diverticulosis when compared to controls suggesting that size and severity are novel risk factors for diverticulitis.

The Characteristics of Diverticular Disease in Caribbean Population: A Control Group Study.

Diverticulosis is not well characterized in the Caribbeans. Our aim was to compare the anatomical presentation of colonic diverticulosis in African Caribbeans (group AC) versus Europeans (group E) and severity. We conducted a prospective controlled study involving 274 patients admitted for lower gastrointestinal haemorrhage (LGIH) in France (center 1: Guadeloupe; center 2: La Roche-sur-Yon); 179 cases with diverticular haemorrhage, including 129 in group AC and 40 in group E. Exploration of the colon included a detailed assessment of diverticula using a dedicated endoscopic grid. AC and E had similar characteristics in terms of age, gender, previous history of LGIH, body mass index, dietary habits, and medications, but AC had significantly poorer hemodynamic parameters at admission and required more blood transfusions (66.7% vs. 42.5%; p=0.01) during hospitalization. Out of the 169 patients included in the study, a complete exploration of the colon was achieved in 81% (N = 137) (AC, n = 106; E, n = 31), and revealed right-side diverticulosis in AC (in 90.6%, included into a pancolonic form in 73.6% vs. 35.5%; p=0.0002) and left-side diverticulosis in E (in 96.8%, isolated form in 58.1% vs. 9.4%, p=0.0002). These data were confirmed by a sensitivity analysis using an endoscopic grid in 92 patients, achieving a higher frequency and larger size of diverticula in AC. Our study has shown that diverticulosis was pancolonic in AC and more frequently associated with more severe haemorrhage than the left-sided diverticulosis of Europeans. This anatomical presentation may be driven by the genetic background more than the environment and diet.

Colonic Diverticulosis and Non-Alcoholic Fatty Liver Disease: Is There a Connection?

Background and Objectives: The development and severity of colonic diverticulosis and non-alcoholic fatty liver disease (NAFLD) has been associated with several components of metabolic syndrome (MetS). Therefore, this study aimed to evaluate a possible connection between NAFLD, colonic diverticulosis, and MetS. Materials and Methods: This retrospective study included patients diagnosed with diverticulosis between January 2017 and December 2019. Data regarding the patient demographics, Diverticular Inflammation and Complication Assessment (DICA) score and category, disease localization, hepatic steatosis, blood pressure, comprehensive metabolic panel, need for colonic surgery, and co-morbidities were collected from medical records. Results: A total of 407 patients with a median age of 68 years (range, 34–89 years) were included (male: 53.81%). The majority was diagnosed with left-sided diverticulosis (n = 367, 90.17%) and an uncomplicated disease course (DICA category 1, n = 347, 85.3%). Concomitant hepatic steatosis was detected in 47.42% (n = 193) of patients. The systolic blood pressure, triglycerides, total cholesterol, C-reactive protein (CRP), and fasting glucose were higher in the NAFLD group (p < 0.001, p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively). A higher prevalence of hypertension (HTA), type 2 diabetes mellitus (T2DM), and hypothyroidism was noted in the same group of patients (p < 0.001, p < 0.001, and p = 0.008, respectively). High-density lipoprotein cholesterol was lower in patients with more severe forms of diverticulosis (DICA category 2 and 3), while CRP levels were significantly higher (p = 0.006 and p = 0.015, respectively). HTA and NAFLD were more common in patients with more severe forms of colonic diverticulosis (p = 0.016 and p = 0.025, respectively). Using a multivariate logistic regression, the DICA score, CRP, total cholesterol, HTA, and hypothyroidism were identified as discriminating factors for the presence of hepatic steatosis. Conclusion: Components of metabolic dysregulation were prominent in patients diagnosed with colonic diverticulosis and concomitant hepatic steatosis. HTA, T2DM, and hypothyroidism were more frequently observed in this group. Hepatic steatosis was more commonly detected in more severe forms of colonic diverticulosis.

The Epidemiology and Etiology of Right-Sided Colonic Diverticulosis: A Review.

Diverticulosis of the colon is a common condition in Western countries and most patients will remain asymptomatic, but some will present with symptoms of acute diverticulitis or bleeding. Our understanding of diverticulosis is evolving but is mostly derived from diverticulosis affecting the left-sided colon. In contrast, right-sided colonic diverticulosis (RCD) is more commonly seen in Asian countries but is much less common overall. Based on the marked differences in epidemiology, it is commonly thought that these are 2 distinct disease processes. A review of the literature describing the epidemiology and etiology of RCD was performed, with a comparison to the current understanding of left-sided diverticulosis. RCD is becoming increasingly common. The epidemiology of RCD shows it to be a mostly acquired condition, and not congenital as previously thought. Many factors in the etiology of RCD are similar to that seen in left-sided diverticulosis, with a few variations. It is therefore likely that most cases of RCD represent the same disease process that is seen in the left colon.

S2313 A Rare Presentation of an IL-12/23 Antagonist in Crohn’s Disease and Development of Sarcoidosis

INTRODUCTION: Anti-tumor necrosis factor (anti-TNF) therapy has been studied for use in inflammatory conditions such as IBD. There is a growing awareness of paradoxical reactions during treatment with this biologic agent. These can be defined as the development or exacerbation of a pathological condition which is triggered by the biologic agent being used. Commonly reported reactions include skin or joint manifestations, colitis or ileitis, or vasculitis. Paradoxically anti-TNF biologics have been reported to be useful to treat sarcoidosis and have been reported to cause sarcoidosis. Ustekinumab an IL-12/23 antagonist has been reported to cause sarcoidosis in 2 patients with psoriasis. We report the first case of a patient developing sarcoidosis during ustekinumab therapy for Crohn’s disease. CASE DESCRIPTION/METHODS: A 49 year-old female with history of breast carcinoma status-post mastectomy and adjuvant chemotherapy presented to clinic with abdominal pain and rectal bleeding. Prior colonoscopy on 6/26/17 only revealed pan-colonic diverticulosis. Colonoscopy on 10/12/18 revealed non-bleeding internal hemorrhoids, left-sided diverticulosis, sigmoid erythema/inflammation, and a normal terminal ileum. Sigmoid biopsies revealed chronic active colitis. She was started on Lialda with symptom resolution. The patient relapsed and was subsequently started on prednisone. Given the improvement with corticosteroids and suspicion of IBD, the patient was started on ustekinumab with a steroid taper and symptoms remained improved. Follow-up positron emission tomography scan for her breast cancer revealed uptake along the esophagus with development of mediastinal and bilateral hilar lymphadenopathy. Since there was concern for cancer, an EGD was performed, revealing only reflux esophagitis. Biopsies by pulmonology of her lymphadenopathy (EBUS) revealed noncaseating granulomatous sarcoidosis without evidence of malignancy. Ustekinumab was discontinued and the patient was restarted back on prednisone and Lialda with improvement. DISCUSSION: Side effects of ustekinumab, a monoclonal antibody to interleukin 12 and 23, can include cancers or serious infections. Our case describes a rare development of sarcoidosis in a Crohn’s Disease patient on ustekinumab therapy. The mechanism for this reaction remains unclear. The case does highlight the importance of knowing that all lymphadenopathy is not due to cancer even in patients with a cancer history and ustekinumab can cause sarcoidosis in patients with inflammatory bowel disease.

Left-Sided Diverticulosis is a Risk Factor for Distal Colon Polyps

BACKGROUND AND AIMS Previous small to mid-sized studies have found an inconsistent relationship between diverticulosis and colon polyps. We assessed the odds of polyps in patients with left-sided diverticulosis (LDV) compared to patients without LDV, and if a predilection for polyps in the distal colon (DC) versus the proximal colon (PC) existed. METHODS In this case-control, retrospective study records of all patients in the Cleveland Clinic undergoing average-risk, screening colonoscopy between January 2011-August 2017 were identified. Baseline characteristics were described. Multivariate logistic regression analysis was performed to identify odds of polyps in PC and DC after adjusting for clinical and colonoscopic factors. RESULTS 50,703 patients (mean age=60 years; 48% male) were included; 38.9% of patients had LDV. Compared to patients without LDV, those with LDV more often had adenomas (33.2% vs 27.8%; p <0.001), hyperplastic polyps (HPs) (18.3% vs 16.2%; p <0.001), and sessile serrated polyps (SSPs) (4.8% vs 4.3%; P=0.011). LDV was associated with adenomas in the DC (OR, 1.59; 95%CI, 1.52, 1.67) more than the PC (OR, 1.15; 95%CI, 1.10, 1.21), with HPs equally in the PC (OR, 1.27; 95%CI, 1.20, 1.34) and DC (OR, 1.28; 95%CI, 1.19, 1.38), and with SSPs in the DC only (OR, 1.50; 95%CI, 1.34, 1.67). CONCLUSIONS LDV is associated with a significantly increased risk of adenomas, HPs, and SSPs, but the association was stronger for adenomas in the DC. Careful inspection of the DC should be encouraged in patients with LDV. More research is needed to understand this phenomenon.

1554 An Unusual Cause of Hematochezia: Anorectal Inflammatory Myoglandular Polyp

INTRODUCTION: Colorectal polyps are an unusual cause of hematochezia and usually result from overlying ulcerations on adenomas or cancers. Non-adenomatous polyps, such as inflammatory polyps, may be a rare cause of gastrointestinal bleeding. Here, we present a case of a patient with painless hematochezia found to be originating from a bleeding anorectal inflammatory myoglandular polyp related to rectal prolapse. CASE DESCRIPTION/METHODS: A 51-year-old man with alcohol abuse and hepatitis C presented with fatigue and light-headedness along with 7-8 years of small volume painless hematochezia with bowel movements. He endorsed straining with bowel movements and something protruding from his anus that he would push back in. On physical exam, he was hemodynamically stable with a normal abdominal exam and a rectal exam revealing a palpable rectal mass without overt signs of bleeding. His lab work was notable for a hemoglobin of 5.5 g/dL. Magnetic resonance imaging (MRI) of the pelvis revealed rectal wall thickening and an enhancing mass abutting the anal sphincter (Figure 1). Colonoscopy revealed left-sided diverticulosis without bleeding and an ulcerated, vascular mass in the anal canal, best seen on retroflexion (Figures 2 and 3). Biopsies of the mass were consistent with an inflammatory myoglandular polyp thought to result from intermittent rectal prolapse. The mass was resected via transanal excision with complete resolution of hematochezia. DISCUSSION: Inflammatory myoglandular polyps are rare, non-neoplastic pedunculated polyps that are predominantly incidental findings during enemas or endoscopy but can present with hematochezia. While concentrated mostly in the distal colon, they can be seen in the descending and transverse colon as well. The etiology remains unknown, but there may be an association with mucosal prolapse and sigmoid diverticulosis. Specifically, it is hypothesized that chronic trauma from intestinal peristalsis may distort colonic crypt architecture, which results in muscularization of the lamina propria. This leads to subsequent redundancy and passive venous congestion that contributes to prolapse of these lesions. Generally, symptomatic inflammatory myoglandular polyps require endoscopic or surgical resection, which is curative. In this case, given the patient's symptoms along with the size and location, surgical management was indicated.

Screening of dementia with resting-state brain activity by two-channel EEG

Colonic diverticulosis is defined as the presence of pouch-like herniations of the mucosa through the fibers of the major muscle layer of the colon. Colonic diverticulosis is extremely common, particularly in middle and older-aged adults. The prevalence of diverticulosis increases with age, and more than two-thirds of the United States population will have diverticulosis of varying degrees by the age of 80 years old. While there have been no reported differences in the prevalence of diverticulosis between men and women, there have been reported geographic differences in the distribution of diverticulosis within the colon. Western populations have predominantly left-sided diverticulosis, while Asian populations have predominantly right-sided diverticulosis. Diverticulosis can be symptomatic or asymptomatic. Diverticular disease refers to symptomatic diverticulosis due to diverticulitis, diverticular bleeding, segmental colitis associated with diverticula, and symptomatic uncomplicated diverticular disease (SUDD).

Medications Associated Polyp Reduction in Patients With Left-Sided Diverticulosis

Medications Associated Polyp Reduction in Patients With Left-Sided Diverticulosis

Mo1664 EXAMINATION OF LEFT-SIDED DIVERTICULOSIS AS A RISK FACTORS FOR DISTAL COLONIC POLYPS

Previous studies examining the relationship between colonic polyps and diverticulosis (DV) demonstrated mixed results. Risk factors associated with adenoma detection significantly overlap factors associated with DV. In this large, single-center study, we hope to evaluate the relationship between rectosigmoid polyps (RSP) and colonic polyps (CP) with presence of DV, while controlling for risk factors associated with polyp detection. Records of all screening colonoscopies performed on patients with average risk in the Cleveland Clinic between January 2011-August 2017 were obtained. Information about patient demographics, comorbidities, procedural details, and pathology were extracted from patient electronic medical record. Differences in frequency of polyps and associated pathology were computed based on presence of diverticulosis. Significance was assessed using chi-square analysis. Next, multivariate analysis was performed to identify factors associated with presence of polyps or polyp pathology after adjusting for factors such as age, gender, race, BMI, insurance, comorbidities (diabetes, cirrhosis, dementia, stroke, constipation, coronary artery disease, heart failure), aspirin use, adequacy of bowel preparation, location, endoscopist specialty, presence of fellow, diverticulosis and withdrawal time. This analysis was done for both proximal colon (cecum to splenic flexure) and distal colon (descending colon to anus). N=52,269 patients were included (mean age =59 (St. dev. ± 8) and 25,155 (48%) were male. Frequencies of polyp distribution in proximal and distal colon based on presence of diverticulosis was computed (Table 1). In Table 1, it can be noted that presence of polyps, adenomas, advanced adenomas, and hyperplastic polyps are all significantly higher in patients with DV regardless of colonic location. However, patients with DV had greater proportion of all of these polyps in the distal colon. Additionally, as noted in adjusted analysis (Table 2), although patients with DV have increased risk of having any polyps, adenomas, hyperplastic polyps, and advanced adenomas on both sides, the magnitude of risk is greater in the distal colon for any polyps (OR=1.72 v. OR=1.23), adenomas (OR=1.62 v. OR=1.16), or advanced adenomas (OR=1.41 v. OR=1.18). WIth DV, SSPs and TV/villous occured more in the distal colon. After adjusting for multiple risk factors associated with polyps, this study demonstrates that left-sided diverticulosis is associated with greater risk of having distal polyps—especially polyps associated with high-risk of colon cancer. This is the largest study to-date to evaluate the phenomenon. While the pathophysiological mechanism is unclear, the findings of this study suggest need for closer examination for polyps in the distal colon and earlier surveillance periods for patients with diverticulosis.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Right-Sided Diverticulosis and Disparities from Left-Sided Diverticulosis in the Vietnamese Population Living in Boston, Mass., USA: A Retrospective Cohort Study

Objective: To report the prevalence, clinical differences and complications of right-sided diverticulosis (RD) and to investigate the potential disparities from left-sided diverticulosis (LD) in the Vietnamese population. Subjects and Methods: A retrospective cohort study was conducted using medical records of Vietnamese-born patients from 2000 to 2013 in a community teaching hospital in Boston, Mass., USA. By simple randomization, a randomized control group of 299 Caucasian patients was also selected from the same time frame [167 males (M) and 132 females (F)]. Colonoscopy reports were reviewed for demographics (age and gender), indication and anatomical location of the colonic diverticulosis (CD), concomitant colonic findings, symptoms, and endoscopic complications. Results: A total of 207 patients were included in the Vietnamese cohort (mean age 61.6 ± 8.9 years). The mean age at first screening colonoscopy was 58.2 ± 7.2 years (114 F/92 M, 55.7/44.4%). Our study identified 104 (50.5%) patients with LD (57 M/47 F), 65 (31.1%) with RD (35 M/30 F) and 38 (18.4%) with both LD and RD (23 M/15 F); 133 (64%) were asymptomatic. A total of 21 (33%) patients with RD were symptomatic. The mean age of the control group was 61.6 ± 8.1 years. The average age at first screening colonoscopy was 52.8 ± 6.4 years. Of the 299 in the Caucasian group, 254 (84.9%) had LD (114 M/140 F), 9 (3.0%) had RD (2 M/7 F) and 36 (12%) had both LD and RD (16 M/20 F); 225 (75%) were asymptomatic and came in for screening colonoscopies. A total of 2 patients (22%) with RD were symptomatic. Conclusion: RD was common in this Vietnamese population, and the prevalence was higher than in the Caucasian control group.

Pattern and distribution of colonic diverticulosis: Analysis of 2877 barium enemas in Thailand

To determine the pattern and distribution of colonic diverticulosis in Thai adults. A review of the computerized radiology database for double contrast barium enema (DCBE) in Thai adults was performed at the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. Incomplete studies and DCBE examinations performed in non-Thai individuals were excluded. The pattern and distribution of colonic diverticulosis detected during DCBE studies from June 2009 to October 2011 were determined. The occurrence of solitary cecal diverticulum, rectal diverticulum and giant diverticulum were reported. Factors influencing the presence of colonic diverticulosis were evaluated. A total of 2877 suitable DCBE examinations were retrospectively reviewed. The mean age of patients was 59.8 ± 14.7 years. Of these patients, 1778 (61.8%) were female and 700 (24.3%) were asymptomatic. Colonic diverticulosis was identified in 820 patients (28.5%). Right-sided diverticulosis (641 cases; 22.3%) was more frequently reported than left-sided diverticulosis (383 cases; 13.3%). Pancolonic diverticulosis was found in 98 cases (3.4%). The occurrence of solitary cecal diverticulum, rectal diverticulum and giant diverticulum were 1.5% (42 cases), 0.4% (12 cases), and 0.03% (1 case), respectively. There was no significant difference in the overall occurrence of colonic diverticulosis between male and female patients (28.3% vs 28.6%, P = 0.85). DCBE examinations performed in patients with some gastrointestinal symptoms revealed the frequent occurrence of colonic diverticulosis compared with those performed in asymptomatic individuals (29.5% vs 25.3%, P = 0.03). Change in bowel habit was strongly associated with the presence of diverticulosis (a relative risk of 1.39; P = 0.005). The presence of diverticulosis was not correlated with age in symptomatic patients or asymptomatic individuals (P > 0.05). Colonic diverticulosis was identified in 28.5% of DCBE examinations in Thai adults. There was no association between the presence of diverticulosis and gender or age.

Retroperitoneal Leiomyosarcoma Presenting as Lower Gastrointestinal Bleeding: A Case Report and Review of the Literature

We report the first known case of a retroperitoneal leiomyosarcoma that presented with an endoscopically defined source of gastrointestinal bleeding in the colon. A 68-year-old male with a history of diverticulosis, hypertension, and hypercholesterolemia who complained of a 3-month history of abdominal pain, nausea, and intermittent hematochezia presented for evaluation of large volume hematochezia and lightheadedness. Colonoscopy revealed left-sided diverticulosis and rectal varices without stigmata of recent bleed. CT scan showed a 26 × 20 × 13 cm heterogeneous retroperitoneal mass and multiple hypodense hepatic lesions. Liver biopsy revealed leiomyosarcoma. In summary, although surgery is the mainstay of treatment, resectability has not improved significantly. Early recognition and aggressive surgery are keys to long-term survival.

Prevalence and Risk Factors for Colonic Diverticulosis in the Average-Risk Lebanese Population Undergoing Screening Colonoscopy

Purpose: Colonic diverticulosis is a relatively common condition. The prevalence is highest in “westernized” nations, where it has been reported to affect anywhere between 5% and 45% of the population, with the vast majority of diverticula being left-sided. The prevalence in Africa and Asia is much lower, where it is found in less than 0.2% of the population, with a predominance of right-sided diverticulosis. Although the exact risk factors for colonic diverticulosis are unknown, studies have suggested that chronic constipation and a low fiber diet may be predisposing factors. Given the overall asymptomatic nature of colonic diverticulosis, it is difficult to obtain an accurate incidence of the condition and its associated risk factors. The aims of this study were to investigate the prevalence of colonic diverticular disease in the average-risk Lebanese population undergoing screening colonoscopy and to identify possible associated risk factors. Methods: Consecutive asymptomatic Lebanese aged≥50 undergoing screening colonoscopy were included in the study. Demographic characteristics and information about smoking, caffeine intake, exercise, dietary habits, and long-term use of NSAIDs, calcium, and multivitamins/antioxidants was collected. The presence or absence of diverticula and their location in the colon was noted for each patient. Results: To date, 500 patients (mean age = 61.2±8.3 years) have been included in the study. The overall prevalence of colonic diverticulosis was 30.5%, with almost equal distribution by gender (prevalence=31.2% in males and 29.8% in females). The diverticula were left-sided in 77.5% of patients, right-sided in 4.5% of patients, and diffuse (both left and right-sided) in 18.0% of patients. On multivariate analysis using backward stepwise logistic regression, alcohol consumption (p=0.001, OR=2.33 (1.39-3.89)), intake of vitamins/antioxidants (p=0.013, OR=1.90 (1.15-3.15)), increasing age (p=0.001, OR=1.73 (1.25-2.38)), and consumption of poultry (p=0.031, OR=1.49 (1.04-2.15)) were all significant risk factors for the development of colonic diverticulosis. Conclusion: The prevalence and site distribution of colonic diverticulosis in the asymptomatic Lebanese population is commensurate with the numbers reported from “westernized” nations, with a relatively high prevalence of predominantly left-sided diverticulosis. As was found in most studies, there is a significant increase in the prevalence of colonic diverticula with increasing age. In addition, alcohol consumption, intake of vitamins/antioxidants, and consumption of poultry were found to be significant independent risk factors for the development of colonic diverticulosis.

The pathology of diverticulosis coli.

Left-sided diverticulosis coli is a common condition in western communities, with 30% to 50% of adults over the age of 60 being affected. It predominantly involves the sigmoid colon. The diverticula (pseudodiverticula) are pockets of mucosa bounded by muscularis mucosae and invested with a thin layer of submucosa, that are forced out through weak points in the muscularis propria, the tips ending in the colonic subserosa. The weak points in the muscle coat are the sites of entry of the nutrient vessels of the colonic mucosa. Diverticulosis is attributed to increased colonic intraluminal pressure while straining at stool in individuals who eat low-fiber diets. Muscular hypertrophy, shortening of the bowel, and thickened mucosal folds due to mucosal redundancy are characteristic of this condition. Complications of diverticulosis include bleeding, diverticulitis, peridiverticular abscess, perforation, stricture, and fistula formation. However, most individuals with diverticulosis are asymptomatic, without evidence of complications. Mucosal changes in the diverticula in uncomplicated diverticulosis include an increased lymphoid infiltrate, development of lymphoglandular complexes, mucin depletion, mild cryptitis, architectural distortion, Paneth cell metaplasia, and ulceration. The mucosa of the remainder of the sigmoid colon (ie, the nondiverticular mucosa) is usually normal, but in about 1% of cases it has features that are indistinguishable from ulcerative colitis or from Crohn's disease (segmental colitis associated with diverticular disease, SCAD). Such cases pose a difficult diagnostic challenge as patients with SCAD respond to medical or surgical therapy for diverticular disease, whereas those with ulcerative colitis or Crohn's disease will develop other manifestations of their disease in time and require different treatment. In SCAD, the mucosal changes are confined to the area of diverticulosis; therefore, histologic evaluation of the rectum (which is unaffected by diverticulosis) and more proximal bowel can be helpful in the differential diagnosis.

Pathophysiology of diverticular disease

There is substantial evidence that colonic diverticulosis is related to civilization, industrialization and a ‘Western’ lifestyle and diet, being described as ‘a disease of Western civilization’. Its increased incidence during the 20th century and the morbidity and mortality associated with complications, demand that this condition should receive greater attention in terms of aetiology, prevention and management. It is generally believed that low dietary fibre and ageing are the two main pathogenic factors involved in this disease. Physiological studies have also demonstrated that there is a higher intraluminal pressure in the large bowel with diverticula. This chapter provides the evidence currently available for the pathophysiology of colonic diverticulosis and discusses its aetiological factors, including low dietary fibre, ageing and intraluminal pressure as well as extracelluar matrix such as collagen and elastin. The difference between the left-sided diverticulosis commonly seen in Caucasians and the right-sided predominantly observed in Asians is also presented.

Pathogenesis and epidemiology of sigmoid diverticulosis

From an epidemiological point of view, left-sided diverticulosis represents a civilizational disease of Western countries. It occurs rarely during childhood and frequently in later years. A diet high in fat and meat, low in vegetables, and with insufficient fiber content apparently encourages its genesis. Physical activity seems to counteract diverticulosis while alcohol consumption, smoking, and caffeine ingestion have no effect. The extent of diverticulosis is not commensurate with the extent of complaints. Only a few patients with diverticula develop diverticulitis. Pathogenetically, several factors play a role in the development of diverticulosis. Elevated intraluminal pressure as well as acquired structural changes of the intestinal wall seem to be decisive factors, which intensify with increasing age. These changes are caused by ultrastructural alterations of the muscle and connective tissue related to collagen and elastin metabolism, which presumably can be genetically determined. Intestinal disturbances of innervation and motility also contribute to the formation of diverticula. The term "hypersegmentation" is an attempt to combine these factors into a single pathogenetic model.

Clinical behavior of complicated right-sided and left-sided diverticulosis

The aim of the study was to characterize the clinical entity of multiple right-sided (RS) diverticular disease, which is uniquely common in Asians. Patients hospitalized with proven diverticular disease from June 1989 to January 1996 were reviewed. Data were retrieved from a prospectively collected computerized database. One hundred eighty consecutive patients were admitted to the Department of Colorectal Surgery, Singapore General Hospital, with multiple diverticular disease. Average age was 65.1 (standard error of the mean, 13.9) years. There were 96 men and 84 women. Women presented, on average, 8.4 years later than men (P < 0.005). Eighty-five patients (47 percent) had massive rectal bleeding, 65 (36 percent) had diverticulitis, 21 (12 percent) had obstructive symptoms, and 9 (15 percent) had enteric fistulas. The diverticula were RS in 76 patients(42 percent), left-sided (LS) in 62 patients (34 percent), and on both sides in 42 patients (24 percent). RS diverticulosis tended to present with massive rectal bleeding (42/76; 55 percent) more often than LS disease (14/62; 23 percent; P < 0.005). Surgery for bleeding was also required more often for RS (17/42; 41 percent) than for LS disease (1/14; 7 percent; P < 0.05); however, diverticulitis was more common on the left (RS, 25/76, 33 percent; LS, 32/62, 52 percent; P < 0.05). Seventy-eight patients (43 percent) required surgery for these complications of diverticular disease. At a mean follow-up of 15.2 (standard error of the mean, 2) months, mortality was 2 in 78 patients who underwent surgery (3 percent), and morbidity was 15 percent. In comparison with LS, RS diverticular disease tended to present more often with massive bleeding than with diverticulitis and fistulation. This bleeding was often more severe and required surgical intervention.

Cecal diverticulitis. A review of the American experience.

The etiology of cecal diverticulitis remains unclear. The majority of diverticula are solitary and probably false and may be the result of the same degenerative process seen in the more common left-sided diverticulosis. A minority are true diverticula and may be of congenital origin. Cecal diverticulitis is clinically indistinguishable from acute appendicitis although patients with cecal diverticulitis tend to be older (average age, 40 years), have a longer duration of symptoms, and present less often with nausea and vomiting. In patients with previous appendectomy and in those with more indolent symptoms, barium enema may be helpful in making the diagnosis. If nonoperative treatment is chosen, careful follow-up with air contrast barium enema and colonoscopy should be carried out. The majority of patients require surgery and two types of cecal diverticulitis are encountered at laparotomy. The usual type, accounting for two thirds of cases, is easy to recognize, has an inflamed projection from the cecal wall, and is dealt with by a limited local diverticulectomy. Some authors advocate nonsurgical treatment for this first group of patients. Incidental appendectomy is advocated to avoid confusion should symptoms occur postoperatively. The hidden variant presents as a large, indurated phlegmon and is difficult to distinguish from a perforated cecal carcinoma. With the hidden variant, right hemicolectomy is the surgical treatment of choice and carries a 1.4 percent mortality.