Colonic diverticula are the most common structural abnormality of the bowel and is the fifth most costly gastrointestinal disorder in Western society.1,2 An acquired condition, diverticula usually affect the sigmoid colon in Western societies, but they are also found on the right colon in countries with diets rich in fiber. The prevalence of diverticular disease has increased during the last century,3 which probably reflects both an increase in detection and an aging population. Until 30 years ago, the proportion of patients requiring surgery or dying from diverticular disease was decreasing4; however, during the last 20 years, the rates of hospital admission and surgical intervention have increased, while inpatient and population mortality rates from diverticular disease have remained unchanged.5
Colonic diverticulum is an acquired condition with increased prevalence with increasing age. It affects fewer than 10% of people in their fifth decade of life, increasing to around 50–66% in their ninth decade.6 Most patients with diverticulosis don't require surgery; however, complications of diverticular disease may. Such surgery can be challenging and good outcomes rely on timely and appropriate intervention.
The terminologies used include diverticulum (diverticula—plural); diverticulosis—asymptomatic diverticula; diverticulitis (simple or complicated)—diverticula with inflammation; diverticular disease—diverticula with or without inflammation.
Diverticular disease was initially described by Littré in 1700 as saccular outpouchings of the colon.7 Cruveilhier is credited with the first clear and detailed description of the pathogenesis of diverticulitis and complicated diverticular disease.8 In 1899 Graser introduced the term “peridiverticulitis” and suggested that diverticula were caused by herniation of colonic mucosa through areas of penetration of the vasa recta. This is now well established as the pathogenesis of colonic diverticulosis.9 In contrast, the mechanism for diverticulitis was not identified until 1904 by Beer.10 He proposed that impacted fecal matter at the neck of the diverticulum caused inflammation and subsequent abscess and fistula formation.
Moynihan reported a case of peridiverticulitis in 1907 and underlined the difficulties in distinguishing diverticular disease from malignancy.11 Telling and Gruner's classic paper describing complex diverticular disease was not published until 1917.12 At this time the prevalence and pathophysiology of diverticular disease were well recognized, as were the complications, including acute diverticulitis, abscess, fistula, perforation, and obstruction.
The development of radiological imaging of the large intestine was important in establishing a diagnosis and documenting the extent of diverticular disease.13 In 1914, De Quervain and Case were the first to demonstrate colonic diverticula with x-rays.14,15
Diverticular disease is a disease of Western populations. A number of studies have shown an increase in incidence over the last 30 years.5,16 Migrant studies likewise confirm an increase in incidence when populations move to a Western country. There is a widely held view that fiber content of food is important, and that the high intraluminal pressure associated with low-fiber diets precipitated by colonic compartmentalization causes an unsustainable increase in tension within the bowel wall. This is compounded by the hyperelastosis and altered collagen structure seen in the colon due to aging.17,18 Both mechanisms ultimately lead to a loss of bowel wall integrity and the formation of diverticula. Exercise and a reduction in the intraluminal pressure associated with a high-fiber diet may be protective.19
High intraluminal pressures are generated because of colonic motility. Colonic motility is complex and not easily studied. The most common motor patterns are tonic segmenting and rhythmic contraction. Tonic segmentation creates stationary narrow rings that appear as haustral markings. Their purpose is to slow the fecal stream and to permit water absorption and electrolyte exchange. Infrequent propulsive peristaltic contractions move fecal matter in a caudal direction; these occur around six times a day.20
The alteration in pressure caused by these movements has been implicated in the pathogenesis of colonic diverticulosis. Several groups have studied colonic motility with intraluminal manometry in humans and animals. Most studies agree that there is increased phasic pressure activity, but this relates more to the presence of symptoms rather than diverticula. The results, however, are heterogenous, principally because of methodological differences, in particular relating to bowel preparation and pressure sensors.21 It may therefore be unreasonable to draw firm conclusions from these investigations.22
More generalized alterations in colonic motility have been implicated in the pathogenesis of colonic diverticular disease. In vitro and in vivo studies, however, are conflicting. Some demonstrate an absence of slow-wave activity (favoring nonpropagating contractile activity) and some demonstrate unimpaired or increased slow-wave activity.23,24 Others have demonstrated an increase in fast-wave activity, which persists after resectional surgery.25 The exact relevance of these myoelectric changes remains uncertain.
Diverticulosis is a Western disease that has a striking geographic distribution. The disease is rare in rural Africa and Asia with the highest prevalence seen in the United States, Europe, and Australia.26 Within a single country, the disease incidence can vary depending on ethnicity.27 Urbanization can also increase diverticular disease incidence, possibly attributable to a dietary change.28,29 The incidence of complicated diverticular disease also seems to be increasing.30
Diverticular disease in Asian patients is often right-sided with manifestations early in life and is often multiple. The reasons for this variation are unknown; however, it has been suggested that both diet and elastin/collagen differences may play a role.31
Colonic diverticula are false diverticula most commonly found in the sigmoid colon (95%). The sigmoid colon is the exclusive site in about 50% and the entire colon is involved in just 5%. The muscular colonic wall is composed of both longitudinal and circular layers. The circular layer of the muscularis propria forms a continuous sheet of muscle throughout the large bowel. The longitudinal layer forms three discrete condensations called taeniae; one of these is adjacent to the mesentery while the other two are antimesenteric. The taeniae coalesce to form an enveloping muscular layer in the rectum. Much of the colonic wall is therefore devoid of longitudinal muscle and it is in these areas that diverticula form. Herniations of muscularis mucosa occur between the taeniae along the arteries (vasa recta) that penetrate the muscle wall en route to the submucosa and mucosa (Figs. 32-1 and 32-2).
Relationship of diverticulum and vasa recta.
Cross section through the sigmoid colon containing diverticula (arrows).
Many studies have demonstrated a change in the histological structure of the muscularis propria in diverticular disease. In a classic study, Whiteway and Morson found the muscle cells to be normal with no evidence of hyperplasia or hypertrophy, but both layers were thickened. They demonstrated excessive amounts of elastin in the taeniae but not in the circular muscle.17 Repeated intermittent distension of the colon can result in increased synthesis of connective tissue components.32 It may be that the Western diet with its lower fecal load only intermittently distends the bowel wall and encourages elastin deposition.
The importance of collagen and elastin types in the colonic wall is increasingly being recognized. Elastin deposition, termed “elastosis,” explains the contracted and thickened appearance of the diverticulum-affected colon. The taeniae shorten, and, because of fascial linkage between the longitudinal and circular muscles, the colonic wall looks like a concertina. Thickened circular muscle folds project into the lumen causing a decrease in caliber. The mesocolon is also foreshortened, possibly as a result of chronic inflammation. Other studies have suggested that the type of collagen may be important.33 One study has shown that in the bowel sections of patients with diverticulitis, there were decreased levels of mature collagen type I and increased levels of collagen type III with a resulting lower collagen I:III ratio. The expression of matrix metalloproteinase 1 was reduced significantly in the diverticulitis group.33 These findings support the theory of structural changes in the colonic wall as one of the predisposing pathogenic factors for the development of diverticula (Fig. 32-3A and 32-3B).33 In those with certain connective tissue diseases, such as Marfan's and Ehlers-Danlos syndromes, diverticular disease is a common association.
A. Sigmoid colon with diverticula. B. Mucosal view of colonic diverticula.
Diverticulitis always starts with a microperforation leading to peridiverticulitis. This is instigated by either a rise in intraluminal pressure and/or erosion by inspissated feces. Nonresolution of this initial injury leads to complications of diverticulitis.
Given the high incidence of diverticulosis, it is surprising that clinical manifestations are relatively infrequent. Many patients are unaware that they have colonic diverticula until they develop acute symptoms or when colonic diverticulosis may be found as an incidental finding when patients are undergoing colonic investigations. Typically an acute attack of diverticulitis begins with lower abdominal pain that then localizes to the left iliac fossa. An inflamed sigmoid colon can lie against the dome of the bladder or the cecum, mimicking a urinary tract infection or appendicitis. Fever, tachycardia, and a leukocytosis accompany the acute attack. The inflammatory response starts at the site of a blocked diverticulum, and bacterial proliferation eventually leads to abscess formation. Minor episodes may be self-limiting, but an abscess can develop and then rupture into the abdomen causing a purulent peritonitis. More rarely, feculent peritonitis occurs when a diverticulum ruptures freely into the peritoneum.34–41
Physical examination will often reveal peritonitis localized to the left iliac fossa or suprapubic area; a palpable mass is not uncommon.
The differential diagnosis includes appendicitis, segmental ischemic colitis, colorectal cancer, inflammatory bowel disease, gastroenteritis, and irritable bowel disease.
In the absence of complications, patients with acute diverticulitis are best managed conservatively with antibiotics. Generalized rigidity suggests purulent or fecal peritonitis, and early surgery is required in this situation. Once fluid and electrolyte resuscitation has begun, an emergency laparotomy or laparoscopy with an appropriate colonic resection should be performed.
Often, diverticular disease presents in a more indolent manner with nagging left iliac fossa pain, abdominal distension, and a change in bowel habits. In the course of investigations to exclude colon cancer, diverticular disease may be discovered by barium enema, computed tomographic (CT) colonography, or colonoscopy (Figs. 32-4, 32-5A, and 32-5B). In the majority of these patients, education about the natural history of the disease with advice on dietary modification and supplementary written information will suffice. A very limited number of patients, who continue to have symptoms despite long periods of medical management, may benefit from surgery in the absence of other specific complications of the disease; however, determining who has symptoms from their diverticula and who has irritable bowel can be difficult. These patients often have persisting symptoms following surgery.
Left colonic diverticula on double-contrast barium enema (arrows).
CT coronal view of sigmoid diverticula.
Feculent peritonitis is usually associated with toxemia and signs of generalized peritonitis. These patients will require an immediate laparotomy, resection, and diversion. Mortality rates for emergency operations have remained unchanged at 12–36% for the last 20 years and are most often affected by the patient's underlying fitness for surgery.
An inflamed segment of sigmoid colon can adhere to a number of intra-abdominal structures or to the abdominal wall. A fistula may arise spontaneously as a result of the inflammatory condition itself or as a result of surgical intervention. It is more common in males, in those with previous abdominal surgery and in immunocompromised patients. Diverticular fistulas can drain either internally or externally. Often, these fistulas are single tracts, but in about 8% of patients they are multiple. Rare sites of fistulous involvement include the ureters, other colonic segments, and stomach.
Occasionally a paracolic diverticular abscess will discharge spontaneously through the abdominal wall causing a colocutaneous fistula. More often, a fistula will result from incision and drainage of a pointing paracolic abscess or from a drain placed under radiological control. A fistula can arise from a leaking colonic anastomosis in patients who have undergone resection for diverticular disease.
This is the most common fistula accounting for about two-thirds of diverticular fistulae. It is more common in men because in women the uterus is interposed between the bladder and the colon. A relatively mobile sigmoid colon becomes adherent to the dome of the bladder and a communication develops. Patients present with recurrent urinary sepsis, urgency, frequency, and pneumaturia. Fecaluria is uncommon. Cystoscopy sometimes identifies an area of inflamed transitional epithelium but is more useful to exclude bladder cancer. A double-contrast enema or CT colonography provides a useful map of the anatomy and in some cases can confirm the presence of a fistula. Caution should be exercised when using barium in an acute situation to avoid peritoneal contamination.
Small bowel can become adherent to an inflamed diverticulum-affected colon. Fistulas form when an abscess discharges through the small bowel wall. This may be asymptomatic.
This is a particularly debilitating fistula. The patient may pass flatus and feces through the vagina and suffer recurrent vaginal infections. Colovaginal fistulas usually only occur if a previous hysterectomy has been performed. Barium studies of both the bowel and the vagina or pelvic magnetic resonance imaging (MRI) usually can confirm the diagnosis. They are also helpful to exclude colonic malignancy as a cause; however, an examination of the vagina may also be required to exclude the rare possibility of a gynecological malignancy.
Single-stage operative resection with primary anastomosis and repair of the contiguous organ can be performed in most circumstances.42 Interposition of the pedicalized greater omentum between the anastomosis and the site of the fistula is a useful adjunct in preventing recurrent fistula formation.
Severe hemorrhage from diverticular disease is rare (5%).43,44 However, distinguishing diverticular bleeding from other causes can be a diagnostic challenge, particularly because diverticular disease is so prevalent.45,46 In elderly patients, angiodysplasia is the most common colonic cause for rectal bleeding. Taken together, bleeding from angiodysplasia and diverticula account for 90% of cases of severe lower intestinal hemorrhage. In diverticular bleeding the penetrating vasa recta that has led to the development of the diverticulum is easily eroded as it is only separated from the bowel lumen and its contents by a thin layer of mucosa. On histology there is thinning of the media and thickening of the intima of the vasa recta with rupture of the vessel usually at the dome of the diverticulum. There usually is no inflammation associated with the bleeding diverticulum.47,48
Diverticular hemorrhage presents with abrupt passage of large-volume bright or dark red blood per rectum and may be associated with lower abdominal pain probably related with colonic distension. Most diverticular bleeding occurs from left-sided diverticula except in patients of Asian ethnic origin, in whom it is more common to find the bleeding occurring on the right side.31 Diverticular bleeding is more common in those on nonsteroidal anti-inflammatory drugs (NSAIDs). Colonoscopy in situations of large-volume bleeding is considered futile if not dangerous. CT angiography is now considered the most useful diagnostic test as it more readily localizes the site of bleeding should the bleeding rate exceed 0.5mL/min. Formal mesenteric angiography to embolize the segmental vessel is then undertaken with good bleeding control and low associated complications (Fig. 32-6).49,50 Failing this, other techniques to control or localize the bleeding site include vasopressin injection or methylene blue. A more sensitive test for colonic bleeding is a radio-labeled red blood cell scan or technetium-99m–labeled sulfur colloid (>0.1 mL/min), but they are poorer in localizing the bleeding site.51 Colonoscopy can be used before a laparotomy or as an adjunct with the abdomen open if all else fails in a patient who continues to bleed. It is useful in an attempt to localize and control the bleeding or to minimize the amount of colonic resection. It is also important to note that in these situations a preoperative gastroscopy is mandatory to exclude an upper gastrointestinal tract (GIT) source of bleeding. Most diverticular hemorrhage ceases spontaneously (70–80%) with rebleeding rates of 22–38%.44,45,52 CT colonography or colonoscopy in patients who have stopped bleeding is useful to exclude malignancy particularly in those with smaller-volume bleeding, with associated suspicious symptoms or where a personal/family history of cancer is significant.
Formal angiography demonstrating “contrast blush”—active bleeding from sigmoid colon.
Obstruction due to diverticular disease accounts for 10–20% of large bowel obstructions (LBOs) in Western society. Diverticular disease causes colonic obstruction through either luminal stenosis as a result of wall edema on top of the already thick walled, fibrotic colon or extrinsic compression from an abscess (Fig. 32-7). Often the obstruction is incomplete. Small bowel obstruction can occur if a loop of small bowel becomes adherent to the inflamed sigmoid colon. The diagnosis is usually apparent from the patient's history. Radiological confirmation either by contrast enema or by CT with oral and rectal contrast should be obtained. Caution is wise in those with questionable underlying active diverticulitis particularly if complicated by localized perforation. Direct visualization and histological exclusion of malignancy are mandatory but at times difficult.
CT scan of active diverticulitis with occlusion of colonic lumen secondary to inflammation (arrow). Differential diagnosis is a sigmoid colon malignancy.
Management of colonic obstruction in this setting depends on the mode of presentation and the medical fitness of the patient. An insidious onset is characterized by pain, increasing constipation, and the passage of ribbon-like stools. The majority of patients, however, will present acutely with a classic LBO. The surgical options include a Hartmann resection and resection with primary anastomosis or rarely with a diverting loop ostomy. In those patients deemed unfit for surgery, the endoscopic or fluoroscopic deployment of a colon stent is a useful alternative procedure with a high clinical success rate.53
Abscess formation is the most common complication of acute diverticulitis. It occurs when the center of the inflammatory mass or phlegmon becomes necrotic. The patient presents with worsening abdominal pain, undulating fever, leukocytosis, and raised inflammatory markers. A mass is often palpable in the left iliac fossa or suprapubic region. It may also be felt transvaginally or transrectally. The most common site for a diverticular abscess is in the sigmoid mesocolon, although a variety of unusual presentations have been described.54 A significant number of abscesses are detected radiologically on CT or ultrasound scanning. Most small (<5 cm) pericolic abscesses can be treated medically with bowel rest and antibiotics.55 CT- or ultrasound-guided drainage is indicated for larger or unresolving abscesses via a transabdominal approach when accessible.41,56–58 (Fig. 32-8) Alternatively, these abscesses may also be drained transanally or transvaginally depending on their location. This is successful in up to 90% and will allow subsequent observational management or a single-stage resection.58–61 Factors that limit success with management include abscess that involve enteric fistulae or multilocular collections especially those containing solid feces. More recently, laparoscopic lavage and drainage have been taken up with enthusiasm by several groups with some promising results.62–65
Sigmoid diverticulitis complicated by a paracolic abscess (with a percutaneous drainage tube in situ).
Giant Colonic Diverticulum.
Giant colonic diverticulum (GCD) was first described in 1946 by Bonvin and Bonte66 in the French literature. The first radiological description was by Hughes and Greene in the American literature in 1953.67 Various names have been used to describe GCD, including solitary air cyst, giant air cyst, giant gas cyst, encysted pneumatocele, colonic pneumocyst, and giant diverticulum. The variety of names highlights the fact that there has been no clear definition or a single accepted name for these poorly defined lesions that present as large gas-filled cysts attached to the colon (diverticulum). GCD are rare clinical entities with just over 100 cases reported. The age at presentation is comparable to that of patients with conventional diverticular disease. Abdominal pain is the most common symptom, affecting 70% of patients, while 10% are asymptomatic. The most common physical finding is an abdominal mass, affecting 60% of patients, while 4% have normal physical examinations. Plain abdominal radiology is usually diagnostic of GCD. Treatment is recommended early, preferably soon after presentation, because of the high complication rate. Surgical treatment may either require a diverticulectomy or segmental resection, and the outcome is usually good.68
There is little evidence to support an association of diverticular disease and colorectal cancer; however, a recent population-based, case-control study from Sweden identified a causal association between sigmoid diverticulitis and a long-term increased risk of left-sided colon cancer.42
The spiral CT scan has changed the investigation of acute diverticular disease with sensitivities of 90–95%. Although it is debatable whether CT alters disease management in minor diverticular disease, it is invaluable in excluding other causes of abdominal pain and documenting the extent of extraluminal disease. In circumstances in which access to CT is limited, a water-soluble contrast study may show mucosal thickening, edema, irregularity, and occasional extravasation of contrast (Fig. 32-9). Sensitivity is high.69 Any free perforation is usually contained in an abscess cavity. Contrast enemas are particularly useful for demonstrating the presence and course of an enteric fistula. Barium should be avoided in the emergency setting, as the consequences of barium-induced peritonitis are catastrophic.
Localized perforation with contrast extravasation into abscess cavity as demonstrated on double-contrast study.
The real advantage that CT scanning affords, in addition to confirmation of the diagnosis, is to direct the treatment of complicated diverticular disease.70–72 Radiologically guided drainage of diverticular abscesses is a useful adjunct to medical management, and can, if successful, avoid the requirement for emergency surgery (see Fig. 32-8).
The role of ultrasound scanning in patients suspected of having diverticular disease has been confined to the treatment and follow-up of diverticular abscess. It is highly operator-dependent, but it can be used to insert drains and to measure the response of the abscess to drainage.
It is normal practice following resolution of the first episode of diverticulitis to assess the colon for extent of disease and to exclude colorectal malignancy. This can be undertaken with colonoscopy, CT colonography, or barium enema. Care must be taken to wait for full resolution of the attack as an inflamed colon is easy to perforate; also, at times colonoscopy may be very difficult or impossible due to inflammatory adhesions. Colonoscopy generally underestimates the extent of the disease.
Other tests available that may be useful in assessing fistulous disease include MRI scans, cystoscopy, fistulogram, vaginogram, or vaginoscopy.
Classification of Diverticulitis
The Hinchey classification is a useful grading system for diverticulitis.34
|Stage I||Diverticulitis with associated pericolic abscess|
|Stage II||Diverticulitis associated with distant abscess (retroperitoneal or pelvic)|
|Stage III||Diverticulitis associated with purulent peritonitis|
|Stage IV||Diverticulitis associated with fecal peritonitis|
More recently, the modified Hinchey classification has been proposed to further subclassify these stages. Stage 0 is clinical, mild diverticulitis without imaging information. Stage I has been subdivided into Ia that is pericolic inflammation. Stage Ib is diverticulitis associated with pericolic abscess. Stage IIa is distant abscess amenable to percutaneous drainage. Stage IIb is complex abscess with or without fistula. Stages III and IV are the same as for the original Hinchey staging.
The majority of patients with acute diverticular disease can be managed conservatively with intravenous antibiotics.73 In the absence of complications, most patients will respond to a targeted course of antimicrobial therapy against predominantly gram-negative rods and anaerobes especially bacteroides species. A combination of metronidazole and ciprofloxacin or a broad-spectrum antibiotic such as meropenem or amoxicillin and clavulanate (Augmentin) is most commonly used.74 There is, however, quite a variation in the treatment regime used among clinicians, and there is no specific regime that has been shown to be superior.75 The decision to operate should be made at a senior level, as the actual number of patients who require resectional surgery for diverticular disease is small.76 The increasing use of interventional radiology and laparoscopic surgery has impacted how diverticular disease is currently managed. This is coupled with a trend to not perform any resectional surgery but, when necessary, to do so with a primary anastomosis in patients presenting with acute complicated diverticulitis.
Surgery in this setting should be reserved for patients who are medically fit with several proven attacks of acute diverticulitis or who have ongoing sequelae from complicated diverticular disease. Even then, caution should be exercised, as a significant minority of patients whose principal symptom is chronic pain will continue to be symptomatic after resectional surgery.77 The patient should be fully informed of this possibility before proceeding with the surgery.
Elective resection has generally been offered to patients who have suffered two attacks of acute diverticulitis in a short period of time, but recommendations have ranged from one to four episodes.55,78,79 The argument has been that this will prevent recurrent diverticulitis as well as its associated complications.81–93 This is based on historical data that suggest recurrences of up to 67%, with higher morbidity (up to 60%) and mortality associated with recurrent diverticulitis particularly after two episodes.35,37,55,79,92,94–105 It was also previously demonstrated that patients older than 50 years respond less well to conservative treatment following successive attacks of diverticulitis; a response rate of only about 6% was reported for the third recurrence.103 In another series re-recurrence was estimated at 2% per year with the first recurrence being the most significant predictor of this.98 Most often, any recurrence that occurs does so in the first 6 months after the initial attack, and recent data would suggest that it is in fact failure of resolution of the inflammation from their first episode rather than a true recurrence. Some have argued that there is a reduction in the recurrence rate of diverticulitis from 12.5 to 6%106,107 with good long-term results following surgery.91,108
There is still a lack of good prospective data comparing surgical intervention with conservative management in this situation. A large population-based study recently has shown very few patients going on to have surgery after initial conservative treatment of diverticulitis.73 Another group showed that successful conservatively treated complicated diseases, in particular abscesses, are not associated with further recurrence or complicated recurrences.98 Recent evidence suggests that less than a quarter of patients having emergency surgery for acute diverticulitis have a previous history, and often complications arise during the first attack of diverticulitis rather than during subsequent episodes.109–111 Such episodes were associated with a more benign course and responded well to nonoperative management.101,112 Two groups have shown that the less severe and more readily conservatively managed complications of pericolic abscess occur in recurrent cases rather than free perforation.39,113 Following elective resection, up to 25% will continue to have symptoms suggesting a coexistent pathology such as irritable bowel.6,77 Up to 16% will develop recurrent diverticulitis with a small percentage requiring further surgery.107,114–118 Furthermore, prophylactic colectomy has a mortality risk of up to 4% and a covering stoma is used in up to 14%, necessitating further operation to reverse.39
Risk-reducing measures in elective surgery include weight control, routine administration of prophylactic preoperative antibiotics, and preoperative optimization of the respiratory status of the patient with chronic pulmonary disease. Attempts have been made to stratify the management of diverticular disease by pathological and radiological means.119,120 In one study patients characterized as having a mild attack of diverticulitis had a 14% risk of having a recurrent episode, whereas severe forms had a risk of 39%. Ultimately, the wide spectrum of disease encountered makes dogmatic statements about intervention unreliable, and sound clinical judgment is still required to decide when to intervene.
Indications for operative intervention are different in two patient subgroups: those younger than 50 years and the immunocompromised. Data on young patients with diverticular disease are mainly retrospective. The prevalence of colonic diverticula has been estimated at between 6 and 9% in the general population 40 years of age or younger, with a male preponderance (62–100%).87,121–123 Patients in this group are thought to have a more virulent course with more complicated recurrences and an aggressive policy of surgical resection has been proposed,80,87,93,95,112,123–127 particularly in obese males.87,128,129 Others more recently have challenged this opinion, arguing that there is no difference between the young and old population.130 There were very few free perforations with recurrent attacks and certainly no increased mortality in this age group73,97,99,122,127,131–134 Whether the higher propensity for a complicated course in this age group is a true association or the presentation has been altered because of delayed diagnosis remains debatable.118,135–137 Between 29 and 55% of younger patients will be readmitted to the hospital with acute diverticulitis following their initial presentation, with the majority (up to 88%) of these subsequently undergoing elective or emergency surgery.76,80,112,123,124,138 A number of these patients were diagnosed at operation for another surgical condition, most often with appendicitis, and were thus often unnecessarily operated on.73,133,134 It is unclear whether there is an advantage to operating after the initial acute attack of diverticulitis in this age group, especially if it is uncomplicated.
It is uncertain whether patients who are chronically immunosuppressed are more at risk of developing diverticular disease. It is thought that patients who have long-term uremia have a higher incidence of diverticulosis, possibly due to chronic constipation and generalized tissue weakness. Patients with polycystic kidney disease have a very high incidence of colonic diverticular disease.139 Several groups have reported that immunocompromised patients with acute diverticulitis have a more complicated course compared to nonimmunosuppressed patients.140–142 Patients who are recipients of renal transplants have a high mortality rate from acute complicated diverticular disease. In some centers, routine colonic screening of patients awaiting renal allografts is performed.143
There is limited evidence that the cessation of smoking and stopping NSAIDs will reduce the rate of recurrent attacks of diverticulitis. There is some evidence that the long-term administration of a poorly absorbed antibiotic will have such an effect.144–148
Emergent Acute Diverticulitis with Localized Peritonitis
Patients with acute diverticulitis present with localized left iliac fossa peritonitis, fever, tachycardia, and a leukocytosis. Tenderness can spread to the hypogastrium and even to the right iliac fossa. Generalized peritonitis is highly suspicious for a free diverticular perforation. Patients should be rehydrated with an intravenous infusion; in septic patients a urinary catheter is invaluable for assessing an adequate hourly urine output. Other supportive measures include oxygen therapy, adequate opioid analgesia, and antimicrobial therapy.
Early oral feeding may commence when tolerated, and a switch to oral antibiotics can be made with signs of resolution of inflammation. In the majority of patients, this conservative therapy will lead to the resolution of symptoms.
The operative rate for complicated diverticulitis overall in the past has been between 19 and 55%.79,84,94,98,99,149 Complicated diverticulitis has been shown by some to be associated with high rates of recurrent complications and high rates of mortality.39,78 The mortality in some reports approaches 40% especially in immunocompromised patients,39,109,150,151 and similarly in those with an ASA of 3 or greater, there is a mortality rate ranging of up to 28%.35–37,39,83,85,94,109,152–154
Emergent Acute Diverticulitis with Generalized Peritonitis
When either an abscess or a diverticulum ruptures into the peritoneal cavity, widespread bacterial contamination ensues with resultant generalized peritonitis. Surgery is principally directed at controlling peritoneal sepsis and should be tailored to each situation. A conservative approach can be taken with elderly and medically unfit patients who are unlikely to survive surgical intervention. The combined use of appropriate antibiotic therapy and regular review is surprisingly successful in this cohort, even in the presence of a pneumoperitoneum.
In patients who are fit for surgery, a period of vigorous resuscitation and antibiotic therapy is still warranted. Even in the face of advanced peritoneal signs, a number of patients will respond to these measures and avoid the requirement for surgery. Serial clinical observation is of greatest benefit when pursuing this course. If there is no sustained improvement in 24 hours, the patient should be offered surgery.
The days of the routine three-staged procedures are gone as there is little place for nonresectional surgery in the emergent situation involving feculent peritonitis. Resection of the affected colon is associated with a lower morbidity and up to three times less mortality compared with nonresection procedures.109,155 The aim of surgery is clear: to remove the source of sepsis and to toilet the abdominal cavity. More recently with the advances in laparoscopic surgery, lavage and drainage of Hinchey types 1–3 have been successfully performed. This avoids unnecessary resection surgery and its associated morbidity and mortality, as well as stoma formation and reversal.156 The apparent confusing and conflicting evidence that outcomes are better following open resection than nonresection and laparoscopic nonresection being better still than open resection still need to be resolved.
The amount of resected tissue depends on the extent of the diverticular disease. At the time of the initial acute surgery, the inflamed bowel needs to be resected. The extent of this resection depends on whether a primary anastomosis is being undertaken or a Hartmann procedure is being performed. When bowel continuity is restored after a Hartmann procedure, total sigmoid colectomy plus removing all of the diverticula- bearing colon and a rectal anastomosis has been shown to reduce the risk of recurrence by some107,115 but not others.118
The decision of whether to undertake an anastomosis in the acute setting is dependent on a number of criteria: the frailty of the patient, the degree of contamination and sepsis, the preparedness of the bowel, and the experience of the surgeon. Hartmann's procedure entails resection of the sigmoid colon with formation of end colostomy and is the safest option when conditions do not favor primary anastomosis. Hartmann's resections are not without their own complications. Up to 50% of patients will never have their stoma closed, particularly the elderly.39,79,157,158 There is also definite morbidity (up to 16%) and mortality (up to 4%) related to restoration of continuity.36,152,157–160 Occasionally there are complications related to rectal stump dehiscence.161
Primary anastomosis can be performed in the emergency setting but only if conditions are wholly favorable.162,163 Performing anastomoses in the presence of gross purulent or fecal contamination is controversial and should only be performed by experienced hands. The requirement for bowel preparation for left-sided anastomosis is equally controversial, but recent studies have cast doubt on the need for this.164 Presacral drainage is often used at the end of the operation but without evidence to its effectiveness.165
Laparoscopic Surgery for Diverticular Disease
The widespread acceptance of laparoscopic surgery has led to its use in both benign and malignant colorectal disease. Laparoscopic surgery in colon cancer is oncologically equivalent to the open approach with better cosmesis, less analgesic usage, and shorter hospital stays.166–168 In the acute situation there is growing popularity of laparoscopic exploration and drainage of Hinchey's stages I and II diverticulitis.41,56–58,169 This is particularly useful in cases of misdiagnosis where diverticulitis is instead found, avoiding the need for a colectomy or stoma. Laparoscopic drainage has even been utilized in some centers for Hinchey's stages III and IV complicated diverticulitis.170 Laparoscopic repair of colonoscopic perforations recently has been successful in numerous cases even with associated diverticular disease of the colon, especially when the pathology is recognized early and there is minimal contamination.171
Laparoscopic colonic resection for diverticular disease is challenging and is being increasingly utilized by specialist centers with good results.172,173 Some groups have included complicated cases, including abscesses and fistulas.174–177 Published studies comparing laparoscopic and open resection of left-sided colonic diverticular disease have demonstrated benefits in terms of shorter hospital stay and convalescence despite a longer operating time.178,179 Major complications as well as the length of the colon resection are generally the same when compared with the traditional open approaches.174–176 Conversions to open depend on factors such as the clinician's surgical experience and the complexity of the diverticular complications involved.180
Publication bias, however, is likely to promote laparoscopic resection as being more favorable, and the true morbidity, cost, and conversion rates may differ from figures published in the medical literature. In over 1100 patients reported over the last 5 years, the postoperative complication rates range from 7.3 to 21%. Conversion rates range between 4 and 14%, operating time from 141 to 300 minutes, and return of bowel activity takes between 2 and 2.9 days.174–176,178 A recent analysis of the cost of laparoscopic surgery compared with open surgery demonstrated that the total cost of the laparoscopic approach was significantly less (US$S3458 vs US$4321; p < .05).178 Clearly this may have economic ramifications for the future.
The prevalence of diverticular disease has increased and is continuing to do so in Western countries. The management of diverticular disease is becoming an increasing financial burden to health systems with limited resources. There is little evidence that a change in lifestyle measures can reduce the prevalence of diverticular disease. Fortunately colonic diverticula are usually asymptomatic.
The acute management of diverticulitis is usually conservative with antibiotics and bowel rest, with few patients needing emergency operations. Abscesses can be adequately treated with percutaneous drainage. When an operation is required, the quality of the surgery appears to be more important than whether the operation is undertaken open or laparoscopically. In the acute setting, the affected segment of colon should be resected. The place of elective resection is uncertain. The wide spectrum of disease encountered makes dogmatic statements about intervention unreliable, and sound clinical judgment is still required to decide when to intervene. Further prospective trials investigating recurrence rates, and in particular risk factors for recurrence, as well as the role of prophylactic surgery in the various subgroups is required.