Published: November 2018
A diverticulum is an abnormal pouch arising from an opening within the wall of the alimentary tract.1 The presence of acquired diverticula in the colon is known as colonic diverticular disease. Asymptomatic diverticular disease may be referred to as diverticulosis. Symptoms of diverticular disease include hemorrhage, inflammation (diverticulitis), stricture or obstruction, and fistulae.
The incidence of diverticulosis in the Western world has progressively increased over the past century. Diverticular disease results in nearly 130,000 hospitalizations in the United States each year and more than 1.5 million outpatient visits.2-4 The incidence of diverticular disease is evenly distributed in males and females but increases with age occurring in less than 10% of those younger than 40 compared with up to 70% of those 80 and older.5 However, more recent data demonstrate an increase in the rate of admissions in patients aged 18 to 44 years who are more likely to be male and have more aggressive disease.6-7 The majority of patients with diverticular disease remain asymptomatic with 25% developing symptoms in their lifetime.8
In the West, diverticulosis is predominantly left sided, with 65% of patients with disease limited to the sigmoid colon, 7% of patients with pan colonic disease, and 4% of patients with isolated disease proximal to the sigmoid.9 In Asian populations, 13% to 25% of patients have primarily right colonic diverticulosis.10
The risk for diverticular disease in influenced by genetic, environmental, and epidemiologic factors (Table 1).
It has been postulated that a diet rich in dietary fiber reduces from the development of colonic diverticulosis, while a diet heavy in processed meats with a paucity of fiber may explain the prevalence of diverticulosis in industrialized countries. The total intake of dietary fiber was found to be inversely proportional to symptomatic diverticular disease,11 and African and Japanese immigrants who adopted a Western diet developed diverticular disease at a similar rates to their adopted countrymen.12
The etiology of how high levels of red meat and fat consumption contribute to the development of diverticulosis is poorly understood, though endoscopic studies found diets rich in red meat and lipids are associated with an increased risk of diverticular disease13 and studies of diet found vegetarian patients have a lower risk of hospitalization compared with individuals who consume meat.14
The belief that ingestion of undigested foods such as nuts, seeds and popcorn can precipitate complications of diverticular disease by lodging in colonic diverticula is inaccurate. Patients should be advised to follow a healthy diet and eat all foods in moderation. A recent prospective trial demonstrated an inverse relationship between the risk of diverticulosis or diverticular complications and consumption of nuts and popcorn. Consumption of popcorn twice a week may be protective against the disease.15
There is no evidence about the effect of alcohol and caffeine on the development of diverticulosis so there are no recommendations regarding consumption of alcohol and caffeine. Though the data are limited, cigarette smoking is associated with adverse effects related to diverticular disease, rate of hospitalization, and the incidence of perforation.16
Diverticular bleeding and inflammation has been associated with aspirin and nonsteroidal anti-inflammatories drugs while statins appear to have protective qualities.17,18 A threefold increased risk of perforation was reported in patients taking steroids at the time of symptoms and a 70% increased risk in patients with a history of steroid use.18 High dose Vitamin D has been associated with a reduced risk of inflammation.19
Increased body mass index, waist circumference, and hip to waist ratio have been associated with an increased risk of diverticulitis and diverticular bleeding.20 Furthermore, body habitus may be prohibitive of certain operative interventions. Physical exercise is known to have a protective effect on the development of symptomatic diverticular disease.21
Ehlers-Danlos, Marfan syndrome, and polycystic kidney disease have been associated with development of diverticular disease.22,23 Data exploring these associations are limited though it seems intuitive that genetic conditions that may influence the integrity of connective tissues would predispose to diverticulosis.
Colonic diverticulae are acquired outpouchings of mucosa and muscularis mucosa that develop on the mesenteric side of the colonic wall (Figure 1). The colon has multiple layers; an internal mucosal layer, an inner circular and an outer longitudinal muscle layer, and a serosal covering. Acquired diverticulae do not contain a muscular or serosal layer and therefore are thin walled. The longitudinal muscle forms 3 distinct tinea coli. Small appendices epiploicae are attached along the side of the colon and share the same blood supply as the mucosa. It must be noted that the longitudinal muscle layer fans out to encompass the rectum, which is also absent of appendices epiploicae. The rectum is spared of diverticular disease.
Diverticulae develop where the circular muscle layer is penetrated by vasa recta to supply the mucosa, a point of weakness in the colonic wall.24 This defect is enlarged by increased intraluminal pressure and is thought to be related to constipation and consequent straining to evacuate. The high colonic pressures can contribute to muscle hypertrophy. The sigmoid colon is the narrowest segment of the large bowel, another theoretical precipitant of segmental diverticulosis.
Asymptomatic diverticulae are typically soft and reducible. They are frequently found incidentally on colonoscopy and abdominal computed tomography (CT) scans. The majority of patients with diverticulosis are asymptomatic. While the incidence of diverticulosis is high, the incidence of diverticulitis is low with less than a quarter of patients progressing to have symptoms over a lifetime.3
The progression of diverticulosis to diverticulitis is poorly understood. The traditional belief is that fecal stasis and obstruction of a diverticulum leads to ischemia, ulceration, bacterial overgrowth and micro perforation. This can lead to peri-diverticular or pelvic abscess, as well as free perforation. The first attack of diverticulitis is commonly the most aggressive with patients being most likely to develop free perforation. Follow-up attacks are less likely to require emergent surgery, as the site of inflammation is more likely to be have been walled off by adhesions of omentum, or other viscera.
Diverticular bleeding is thought to be associated with baropressure causing the vasorecta to stretch and rupture. It is arterial bleeding from a branch at the dome or neck of the diverticulum.25 Histological assessment of the bleeding point has demonstrated an absence of diverticulitis.26 As such, this condition is painless and is not associated with colonic inflammation. It must be stressed that rectal bleeding and pain is typically associated with a form of colitis and not diverticular disease. Diverticulosis in such patients is not infrequent, but most likely unrelated.
Acute diverticulitis can be uncomplicated, smoldering, or complicated. The acute presentation is typically described as a constellation of “left sided appendicitis” characterized by left lower quadrant pain, fevers and leukocytosis, which is highly suggestive of sigmoid diverticulitis.27 An astute clinician must be aware of a mobile sigmoid colon that will result in suprapubic or right sided peritoneal signs due to local irritation of the abdominal wall by the inflamed sigmoid colon. Common differential diagnoses of sigmoid diverticulitis are described in Table 2. Routine investigations include blood, serum, and urine analysis as well as radiological imaging. These tests help classify the severity of disease and guide management. Diverticulitis involving other parts of the colon is atypical and is much more difficult to diagnose without focused radiological imaging.
|Colitis: Infective, inflammatory, ischemic|
Smoldering diverticulitis is a condition where patients have persistent symptoms of uncomplicated diverticulitis, but are refractory to medical management while not progressing to diverticular complications. A list of diverticular complications, known as complicated diverticulitis is described in Table 3. Patients with such complications are unlikely to respond to medical therapy alone and require operative intervention.
|Free perforation and peritonitis|
|Colonic stricture and bowel obstruction|
|Enteric fistula (colovesical, colovaginal, colocutaneous)|
|Small bowel obstruction|
|Diverticular Bleeding (complication of diverticulosis)|
Assessment of severity in acute diverticulitis can be time critical. The Hinchey Classification, first published in 1978,28 is the most common method used to grade the severity of acute disease. Currently, the modified Hinchey Classification is more frequently utilized due to the advances in diagnostic and interventional radiology (Table 4).29
|Stage 0||Mild clinical diverticulitis|
|Stage Ia||Confined pericolic inflammatory phlegmon|
|Stage Ib||Confined pericolonic abscess (within sigmoid mesocolon)|
|Stage II||Pelvic, distant intra-abdominal or intraperitoneal abscess|
|Stage III||Generalized purulent peritonitis|
|Stage IV||Fecal peritonitis|
Though the diagnosis of diverticulitis can be made on history and physical examination, radiological adjuncts help to gauge acuity and aid with the management plan. There is still a role for an abdominal film in the appropriate settings. This is a quick and readily available investigation that will demonstrate signs of obstruction or pneumoperitoneum, and direct subsequent investigation and intervention.
American Society of Colon and Rectal Surgeons guidelines state that CT imaging is the most appropriate initial imaging modality in the assessment of suspected diverticulitis, while Ultrasound and magnetic resonance imaging can be useful alternatives in patients who have relative contraindications to CT scan (pregnancy, renal insufficiency, contrast allergy).27 Using CT imaging with intravenous and luminal contrast, clinicians are able to diagnose complications of diverticulitis with a sensitivity as high as 98% and specificity of 99%.30 More so, cross sectional imaging provides the ability to diagnose other intra-abdominal pathologies that may mimic diverticulitis.31 Combining rectal contrast with CT cross-sectional imaging increases the accuracy further, with a reported specificity of 100%.32
The use of contrast enema studies is limited in light of CT imaging. In select cases of suspected large bowel obstruction, the dynamic role of a (gastrografin) enema study may increase the rate of contrast reaching the right colon compared with CT.
The latest American Society of Colon and Rectal Surgeons guidelines recommend that in the setting of a first episode of diverticulitis, or where recent colonoscopies have not been performed, the colon should be endoscopically evaluated to confirm the diagnosis, following resolution of acute symptoms.27 Typically, an elective colonoscopy is scheduled 6 to 8 weeks following the attack.
In cases of complicated diverticular disease, where a colonic fistula is present, a colonoscopy can confirm the site and etiology of the fistula.
An algorithm for the management of patients with diverticular disease is presented in Table 5. Details as to the reasoning for this algorithm are described below.
|Disease complexity||Severity||Medical and interventional management||Definitive operative management|
|Uncomplicated||Hinchey 0 (first presentation)||
||No role for surgical intervention|
|Hinchey 0 (recurrent episode)||
||Consider elective resection if disease effecting quality of life|
|Hinchey 0 or I
||Elective sigmoid colon resection|
||Surgical resection if symptoms progress following percutaneous drainage or during evolution of diverticular complications|
||Surgical resection with consideration of fecal diversion.
Laparoscopic washout in selected cases
||Surgical resection with fecal diversion|
||Surgical resection with anastomosis and consideration of proximal diverting ostomy|
|Acute large bowel obstruction||
||Surgical resection with likely fecal diversion|
|Colovesical/ Colovaginal fistula||
||Surgical resection with consideration of temporary fecal diversion.
Removal of fistula tract Repair of bladder and/or vagina
||Subtotal colectomy and end ileostomy indicated in patients with persistent bleeding not controlled with endoscopic and angiographic interventions.|
CT = Computed tomography; IBD = Inflammatory bowel disease; PRBC = packed red blood cells.
The notion that patients with uncomplicated diverticulitis are able to be managed in the outpatient setting is supported by a consensus from multiple national and international guidelines.33 For patients with mild, Hinchey I diverticulitis, the role of antibiotics is controversial. Recent randomized Dutch and Swedish trials demonstrated that in 6 to 12 months there was no significant difference in time to complete recovery or recurrence rates in either the antibiotic or observation arms.34,35 The latest recommendation for the treatment of uncomplicated acute diverticulitis published by the American Gastroenterological Association institute advises selective administration of antibiotics based on patient characteristics.36
Patients presenting with Hinchey II diverticulitis with an abscess ≥ 4 cm typically require percutaneous drainage, while patients with smaller abscesses typically respond to antibiotics alone.37,38 Percutaneous drainage is frequently performed via a trans-abdominal approach. For pelvic abscesses not amendable to drainage via the abdominal wall, a trans-gluteal approach is considered, though this is typically associated with greater patient discomfort. Transrectal or transvaginal drainage may be performed in select patients.
Patients who are not amendable to percutaneous drainage can be safely treated with antibiotics alone.39 This may be a good option as a bridge to surgery in patients who can benefit from preoperative optimization.
It is not possible to clinically differentiate between Hinchey III and Hinchey IV generalized peritonitis. This diagnosis is made intraoperatively. Feculent peritonitis (Hinchey IV) develops in the setting of a ruptured diverticulum and free perforation. Purulent peritonitis (Hinchey III) is due to a ruptured diverticular abscess, in which case the original perforation had time to be sealed. Operative therapy for purulent or feculent peritonitis should generally include a resection of the diverticular segment.27 The extent of resection should include the acutely diseased colon with margins of healthy colon and rectum. The decision to create an anastomosis in the presence of generalized peritonitis is dependent on patient factors and is individualized. Creating a diversion proximal to the inflamed diverticular segment, without resection of the sigmoid colon, was the historical approach to the emergent treatment of perforated diverticulitis, but is now only reserved for the most difficult scenarios.
Laparoscopic lavage has been described as an alternate surgical modality in patients with Hinchey III peritonitis. While an attractive option that avoids the morbidity of colonic resection and possible stoma formation, it is currently not recommended by the American Society of Colon and Rectal Surgeons due to a high failure to obtain source control.27
Colonic obstruction due to acute diverticulitis is uncommon. Classically, a stricture develops due to gradual contraction of the colonic wall in the setting of chronic inflammation.
Typically, patients present with symptoms of progressive obstruction due to gradual stricture formation at the site of a previous attack of acute diverticulitis. A diverticular stricture should be managed as a colonic adenocarcinoma until proven otherwise, as such resection with a lymph node clearance is required in such patients.40 Colonic stenting, though of limited benefit, has been described as a bridge to definitive surgery in patients that would benefit from preoperative optimization.41 A prompt completion colonoscopy or virtual colonoscopy is required exclude synchronous colonic pathology.
The rate of fistula formation in the setting of diverticular disease is well recognized and can develop in up to 2% of cases.42 Colovesical fistulas are most common and are responsible for 50% of all fistulas associated with diverticular disease.42 Colocutaneous fistulas typically occur following interventional radiology drainage of a diverticular abscess, where an internal opening persists in the colonic wall. Colovaginal fistulas occur in women with a previous hysterectomy. Coloenteric and colouterine fistulas have been described, but are very infrequent. Neoplasia and Crohn’s disease must always be considered as a differential diagnosis, particularly in less common types of fistulas. Colonoscopy is the gold standard test to address the etiology of the colonic fistula. A cystoscopy or vaginoscopy may be of benefit in selected cases.
Colovaginal fistulas present with vaginal discharge, and colovesical fistulas present with pneumaturia or fecaluria. These symptoms are typically associated with significant distress for the patients and their families. It is uncommon for patients to develop systemic sepsis in association with diverticular fistulas, as such the preoperative investigations can be carried out in an outpatient setting. A one-stage resection of the sigmoid colon and associated fistula is typically carried out as an elective procedure.42
Diverticular bleeding occurs in 3% to 5% of patients with colonic diverticular disease.43 The principles in managing patients with diverticular bleeding involves: resuscitation, confirmation of diagnosis, hemostasis and prevention of recurrence. Diverticular bleeding can result in large volume blood loss. As such, appropriate resuscitation, monitored environment, and activation of a massive transfusion protocol may be necessary. Diverticular hemorrhage stops spontaneously in up to 80% of patients, with a rebleed rate between 22% to 38%.43
Diagnosis of diverticular bleeding can be confirmed with either colonoscopic or radiological visualization.44 The advantage of colonoscopy is that it is accurate at confirming the etiology of bleeding, localizing the site, and has the potential to control the hemorrhage with endoscopic intervention. The disadvantage of colonoscopy is that without bowel preparation, there is a low cecal intubation rate (55% to 70%),43 as well as up to a 2.5% perforation risk in cases where therapeutic coagulation is utilized.44
Computed tomography angiography (CTA) has superseded the nuclear red blood cell scan and can identify lower gastrointestinal bleeding at rates as low as 0.3 mL/min,43 however the intermittent nature of diverticular bleeding can make the diagnosis challenging. Following radiological identification of diverticular bleeding, selective embolization is successful in 85% of patients.45
Surgery for diverticular bleeding is only indicated in patients who have persistent bleeding not controlled with endoscopic and angiographic interventions.33 Patients without preoperative localization require a subtotal colectomy and end ileostomy. It must be noted that even in patients with preoperative localization, a segmental colectomy carriers a rebleed rate of up to 14%.43
The notion that an elective sigmoid resection should be performed after a second or third attack of uncomplicated diverticulitis are no longer supported by international guidelines.33 The of elective surgery for patients with a history of diverticulitis should be individualized.27 The surgical risk due to patient specific comorbidities should be balanced against the impact on quality of life due to recurrent attacks.
The rate or recurrence of diverticulitis following a sigmoid colectomy is between 1% and 10%.8 It is thought the reduced bowel luminal diameter of the sigmoid results in a relative high pressure zone, precipitating proximal inflation. Recurrence is reduced by ensuring that all of the sigmoid is resected and the proximal colon is anastomosed to the rectum.46 It must be noted that for patients who have recovered from complicated diverticulitis, an elective colectomy should typically be considered.27
The widespread prevalence of diverticular disease and colonic adenocarcinoma in the Western world may sometimes lead to patients presenting with dual pathologies. A causal relationship has been hypothesized, but not proven. These 2 diseases are plausibly separate entities though they share common risk factors: advanced age, obesity, sedentary lifestyle, consumption of increased red meat and lack of dietary fiber. Most recent studies have demonstrated that the risk of colon cancer is not increased in patients after the first year of being diagnosed with diverticular disease.47 The increased incidence of cancer within the first 12 months reflects the difficulties with differential diagnosis and common symptomatology and screening effects.
Historically, episodes of diverticulitis in young patients were considered to be more aggressive so a lower threshold for operative surgery was advised. Due to cumulative risk, younger patients have a higher rate of recurrence, but this is still relatively low (27%), furthermore, only 7.5% of young patients go on to require subsequent emergency surgery.48 As such, routine elective resection based on young age (< 50 years) is no longer recommended by the American Society of Colon and Rectal Surgeons.27
Immunosuppressed patients are more likely to fail medical management of acute diverticulitis. They are more likely to undergo emergency surgery and develop recurrences and complications of acute diverticulitis,33 thus a lower threshold for elective resection following an attack of uncomplicated diverticulitis should be considered in these patients.42 Prophylactic resection in transplant patients with proven diverticulosis remains controversial.27,33
SCAD is a colonic inflammatory disorder thought to be within the spectrum of inflammatory bowel disease.49 The same entity has also been called diverticular colitis and diverticular disease-associated colitis. The exact pathophysiology of SCAD is unknown, though it has been postulated that fecal stasis and microbial dysbiosis associated with diverticulosis can act as an environmental trigger to precipitate segmental colitis.50,51 The incidence of SCAD is 4 in 100,000, with a median age of 68, similar to the second peak of inflammatory bowel disease.52
Following endoscopic assessment and histological grading, patients are treated as a mild form of inflammatory bowel disease, typically with mesalamine enemas, local steroids (beclomethasone) and probiotics.49