Incidence and Epidemiology
Among Western populations, diverticulosis of the colon affects nearly one-half of individuals older than age 60 years. Fortunately, only 20% of patients with diverticulosis develop symptomatic disease. However, in the United States, diverticular disease results in >200,000 hospitalizations annually, making it the fifth most costly gastrointestinal disorder. The incidence of the disease is on the rise, mainly among young patients. The mean age at presentation of the disease is 59 years. Although the prevalence among females and males is similar, males tend to present at a younger age. Diverticulosis is rare in underdeveloped countries, where diets include more fiber and roughage. However, shortly following migration to the United States, immigrants will develop diverticular disease at the same rate as U.S. natives.
Anatomy and Pathophysiology
Two types of diverticula occur in the intestine: true and false (or pseudodiverticula). A true diverticulum is a saclike herniation of the entire bowel wall, whereas a pseudodiverticulum involves only a protrusion of the mucosa through the muscularis propria of the colon (Fig. 297-1). The type of diverticulum affecting the colon is the pseudodiverticulum. The protrusion occurs at the point where the nutrient artery, or vasa recti, penetrates through the muscularis propria, resulting in a break in the integrity of the colonic wall. Diverticula commonly affect the sigmoid colon; only 5% of persons exhibit pancolonic diverticula. This anatomic restriction may be a result of the relative high-pressure zone within the muscular sigmoid colon. Thus, higher-amplitude contractions combined with constipated, high-fat-content stool within the sigmoid lumen results in the creation of these diverticula. Diverticulitis is inflammation of a diverticulum. The cause is not well understood and is probably multifactorial. The predominant theory is the retention of particulate material within the diverticular sac and the formation of a fecalith. Consequently, the vasa recti is either compressed or eroded, leading to either perforation or bleeding.
Gross and microscopic view of sigmoid diverticular disease. Arrows mark an inflamed diverticulum with the diverticular wall made up only of mucosa.
Presentation, Evaluation, and Management of Diverticular Bleeding
Hemorrhage from a colonic diverticulum is the most common cause of hematochezia in patients >60 years, yet only 20% of patients with diverticulosis will have gastrointestinal bleeding. Patients at increased risk for bleeding tend to be hypertensive, have atherosclerosis, and regularly use nonsteroidal anti-inflammatory agents. Most bleeds are self-limited and stop spontaneously with bowel rest. The lifetime risk of rebleeding is 25%.
Localization of diverticular bleeding should include colonoscopy, which may be both diagnostic and therapeutic in the management of mild to moderate diverticular bleeding. If the patient is stable, massive bleeding is best managed by angiography. Mesenteric angiography can localize the bleeding site and occlude the bleeding vessel successfully with a coil in 80% of cases. The patient can then be followed closely with repetitive colonoscopy, if necessary, looking for evidence of colonic ischemia. Alternatively, a segmental resection of the colon can be undertaken to eliminate the risk of further bleeding. This may be advantageous in patients on chronic blood thinners. However, with newer techniques of highly selective coil embolization, the rate of colonic ischemia is <10% and the risk of acute rebleeding is <25%. Long-term results (40 months) indicate that more than 50% of patients with acute diverticular bleeds have had definitive treatment with highly selective angiography.
As another alternative, a selective infusion of vasopressin can be given to stop the hemorrhage, although this has been associated with significant complications, including myocardial infarction and intestinal ischemia. Furthermore, bleeding recurs in 50% of patients once the infusion is stopped. Localization studies indicate that bleeding as a result of colonic diverticulosis is more often seen from the right colon. For this reason, patients with presumed bleeding from diverticular disease requiring emergent surgery without localization should undergo a total abdominal colectomy. If the patient is unstable or has had a 6-unit bleed within 24 h, current recommendations are that surgery should be performed. In patients without severe comorbidities, surgical resection can be performed with a primary anastomosis. A higher anastomotic leak rate has been reported in patients who received >10 units of blood.
Presentation, Evaluation, and Staging of Diverticulitis
Acute uncomplicated diverticulitis characteristically presents with fever, anorexia, left lower quadrant abdominal pain, and obstipation (Table 297-1). In <25% of cases, patients may present with generalized peritonitis indicating the presence of a diverticular perforation. If a pericolonic abscess has formed, the patient may have abdominal distention and signs of localized peritonitis. Laboratory investigations will demonstrate a leukocytosis. Rarely, a patient may present with an air-fluid level in the left lower quadrant on plain abdominal film. This is a giant diverticulum of the sigmoid colon and is managed with resection to avoid impending perforation.
Table 297-1 Presentation of Diverticular Disease |Favorite Table|Download (.pdf)
Table 297-1 Presentation of Diverticular Disease
|Uncomplicated Diverticular Disease—75%|
|Complicated Diverticular Disease—25%|
The diagnosis of diverticulitis is best made on CT with the following findings: sigmoid diverticula, thickened colonic wall >4 mm, and inflammation within the pericolic fat ± the collection of contrast material or fluid. In 16% of patients, an abdominal abscess may be present. Symptoms of irritable bowel syndrome (IBS) may mimic those of diverticulitis. Therefore, suspected diverticulitis that does not meet CT criteria or is not associated with a leukocytosis or fever is not diverticular disease. Other conditions that can mimic diverticular disease include an ovarian cyst, endometriosis, acute appendicitis, and pelvic inflammatory disease.
Barium enema or colonoscopy should not be performed in the acute setting because of the higher risk of colonic perforation associated with insufflation or insertion of barium-based contrast material under pressure. A sigmoid malignancy can masquerade as diverticular disease. Therefore, a colonoscopy should be performed ˜6 weeks after an attack of diverticular disease.
Complicated diverticular disease is defined as diverticular disease associated with an abscess or perforation and less commonly with a fistula (Table 297-1). Perforated diverticular disease is staged using the Hinchey classification system (Fig. 297-2). This staging system was developed to predict outcomes following the surgical management of complicated diverticular disease. In complicated diverticular disease with fistula formation, common locations include cutaneous, vaginal, or vesicle fistulas. These conditions present with either passage of stool through the skin or vagina or the presence of air in the urinary stream (pneumaturia). Colovaginal fistulas are more common in women who have undergone a hysterectomy.
Hinchey classification of diverticulitis. Stage I: Perforated diverticulitis with a confined paracolic abscess. Stage II: Perforated diverticulitis that has closed spontaneously with distant abscess formation. Stage III: Noncommunicating perforated diverticulitis with fecal peritonitis (the diverticular neck is closed off and therefore contrast will not freely expel on radiographic images). Stage IV: Perforation and free communication with the peritoneum, resulting in fecal peritonitis.
Treatment: Diverticular Disease
Asymptomatic diverticular disease discovered on imaging studies or at the time of colonoscopy is best managed by diet alterations. Patients should be instructed to eat a fiber-enriched diet that includes 30 g of fiber each day. Supplementary fiber products such as Metamucil, Fibercon, or Citrucel are useful. The incidence of complicated diverticular disease appears to be increased in patients who smoke. Therefore, patients should be encouraged to refrain from smoking. The historical recommendation to avoid eating nuts is not based on more than anecdotal data.
Symptomatic uncomplicated diverticular disease with confirmation of inflammation and infection within the colon should be treated initially with antibiotics and bowel rest. Nearly 75% of patients hospitalized for acute diverticulitis will respond to nonoperative treatment with a suitable antimicrobial regimen. The current recommended antimicrobial coverage is trimethoprim/sulfamethoxazole or ciprofloxacin and metronidazole targeting aerobic gram-negative rods and anaerobic bacteria. Unfortunately, these agents do not cover enterococci, and the addition of ampicillin to this regimen for nonresponders is recommended. Alternatively, single-agent therapy with a third-generation penicillin such as IV piperacillin or oral penicillin/clavulanic acid may be effective. The usual course of antibiotics is 7–10 days. Patients should remain on a limited diet until their pain resolves.
For long-term medical management of uncomplicated diverticular disease, rifaximin (a poorly absorbed broad-spectrum antibiotic), when compared to fiber alone, is associated with 30% less frequent recurrent symptoms from uncomplicated diverticular disease. Furthermore, the use of probiotics has been shown to decrease the incidence of recurrent attacks. Culture data from patients on probiotics noted a decrease in the presence of Clostridium species and an increase in Lactobacillus and Bifidobacterium strains.
Preoperative risk factors influencing postoperative mortality rates include higher American Society of Anesthesiologists (ASA) physical status class (Table 297-2) and preexisting organ failure. In patients who are low risk (ASA P1 and P2), surgical therapy can be offered to those who do not rapidly improve on medical therapy. For uncomplicated diverticular disease, studies indicate that medical therapy can be continued beyond two attacks without an increased risk of perforation requiring a colostomy. However, patients on immunosuppressive therapy, in chronic renal failure, or with a collagen-vascular disease have a fivefold greater risk of perforation during recurrent attacks. Surgical therapy is indicated in all low-surgical-risk patients with complicated diverticular disease.
Table 297-2 American Society of Anesthesiologists Physical Status Classification System |Favorite Table|Download (.pdf)
Table 297-2 American Society of Anesthesiologists Physical Status Classification System
|P1||A normal healthy patient|
|P2||A patient with mild systemic disease|
|P3||A patient with severe systemic disease|
|P4||A patient with severe systemic disease that is a constant threat to life|
|P5||A moribund patient who is not expected to survive without the operation|
|P6||A declared brain-dead patient whose organs are being removed for donor purposes|
The goals of surgical management of diverticular disease include controlling sepsis, eliminating complications such as fistula or obstruction, removing the diseased colonic segment, and restoring intestinal continuity. These goals must be obtained while minimizing morbidity rate, length of hospitalization, and cost in addition to maximizing survival and quality of life. Table 297-3 lists the operations most commonly indicated based upon Hinchey classification and the predicted morbidity and mortality rates. Surgical objectives include removal of the diseased sigmoid down to the rectosigmoid junction. Failure to do this may result in recurrent disease. The current options for uncomplicated diverticular disease include an open sigmoid resection or a laparoscopic sigmoid resection. The benefits of laparoscopic resection over open surgical techniques include early discharge (by at least 1 day), less narcotic use, less postoperative complications, and an earlier return to work.
Table 297-3 Outcome Following Surgical Therapy for Complicated Diverticular Disease |Favorite Table|Download (.pdf)
Table 297-3 Outcome Following Surgical Therapy for Complicated Diverticular Disease
|Hinchey Stage||Operative Procedure||Anastomotic Leak Rate, %||Overall Morbidity rate, %|
|I||Resection with primary anastomosis without diverting stoma||3.8||22|
|II||Resection with primary anastomosis +/− diversion||3.8||30|
|III||Hartmann's procedure vs. diverting colostomy and omental pedal graft||—||0 vs. 6 mortality|
|IV||Hartmann's procedure vs. diverting colostomy and omental pedicle graft||—||6 vs. 2 mortality|
The options for the surgical management of complicated diverticular disease (Fig. 297-3) include the following: (1) proximal diversion of the fecal stream with an ileostomy or colostomy and sutured omental patch with drainage, (2) resection with colostomy and mucous fistula or closure of distal bowel with formation of a Hartmann's pouch, (3) resection with anastomosis (coloproctostomy), or (4) resection with anastomosis and diversion (coloproctostomy with loop ileostomy or colostomy). Laparoscopic techniques have been employed for complicated diverticular disease; however, higher conversion rates to open techniques have been reported.
Methods of surgical management of complicated diverticular disease. (1) Drainage, omental pedicle graft, and proximal diversion. (2) Hartmann's procedure. (3) Sigmoid resection with coloproctostomy. (4) Sigmoid resection with coloproctostomy and proximal diversion.
Patients with Hinchey stages I and II disease are managed with percutaneous drainage followed by resection with anastomosis about 6 weeks later. Percutaneous drainage is recommended for abscesses ≥5 cm with a well-defined wall that is accessible. Paracolic abscesses <5 cm in size may resolve with antibiotics alone. Contraindications to percutaneous drainage are no percutaneous access route, pneumoperitoneum, and fecal peritonitis. Urgent operative intervention is undertaken if patients develop generalized peritonitis, and most will need to be managed with a Hartmann's procedure. In selected cases, nonoperative therapy may be considered. In one nonrandomized study, nonoperative management of isolated paracolic abscesses (Hinchey stage I) was associated with only a 20% recurrence rate at 2 years. More than 80% of patients with distant abscesses (Hinchey stage II) required surgical resection for recurrent symptoms.
Hinchey stage III disease is managed with a Hartmann's procedure or with primary anastomosis and proximal diversion. If the patient has significant comorbidities, making operative intervention risky, a limited procedure including intraoperative peritoneal lavage (irrigation), omental patch to the oversewn perforation, and proximal diversion of the fecal stream with either an ileostomy or transverse colostomy can be performed. No anastomosis of any type should be attempted in Hinchey stage IV disease. A limited approach to these patients is associated with a decreased mortality rate.
Recurrent abdominal symptoms following surgical resection for diverticular disease occurs in 10% of patients. Recurrent diverticular disease develops in patients following inadequate surgical resection. A retained segment of diseased rectosigmoid colon is associated with twice the incidence of recurrence. IBS may also cause recurrence of initial symptoms. Patients undergoing surgical resection for presumed diverticulitis and symptoms of abdominal cramping and irregular loose bowel movements consistent with IBS have functionally poorer outcomes.