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M. Shane McNevin, MD, FASCRS

Surgical Specialists of Spokane

Spokane, WA


Colonic diverticular disease is largely a phenomenon of the developed world. Diverticular disease was originally described in the 17th century but current knowledge of the disorder is largely due to work during the last century. A number of recent studies have documented an alarming increase in both incidence and complications of the disorder in the 20th century. Prevalence of the disorder increases with age affecting approximately 40% of people by the age of 65 years and 60% of people by the age of 80 years. Diverticular disease tends to affect the sexes equally although there is data to suggest that inflammatory complications differ with age and sex of the patient.
The majority of colonic diverticular disease is acquired although uncommon congenital diverticula of the colon have been described. Acquired diverticula of the colon are false or pseudodiverticula involving a herniation of only the colonic mucosa and muscularis mucosa through the bowel wall. This occurs at sites of perforation of the bowel wall by the vasa recta typically on the antimesenteric taenia coli. The sigmoid colon is most commonly affected by diverticular change being involved in greater that 90% of cases. Proximal colonic diverticulosis can affect 40% of patients. In contradistinction, congenital diverticula of the colon are true diverticula involving all layers of the bowel wall and are predominately solitary and right sided. 
Although not definitely proven, current thought places causation squarely upon the highly processed Western diet lacking in dietary fiber. This low fiber diet results in small, hard stools requiring elevated intra-colonic pressure for transit through the lower gastrointestinal tract resulting in these acquired or pulsion diverticula. Inflammatory complications of diverticulosis result from perforation of these false diverticula. Perforation is thought to occur when the intra-luminal colonic pressure exceeds the wall tension of the diverticula. Previous thought that perforation resulting from diverticular luminal obstruction by certain foodstuffs, e.g. nuts, seeds, popcorn, has largely been abandoned. Inflammatory complications of diverticular disease are largely isolated to the sigmoid colon. Right sided diverticulitis is more common is Asian populations and has a similar natural history as its left sided counterpart. Being less common in the Western world right sided diverticulitis which often mimics other right sided inflammatory conditions often is diagnosed at the time of surgery.
Symptoms of acute diverticulitis are usually quite typical making history and physical examination useful and usually diagnostic. The majority of patients will complain of focal pain localized to the left lower quadrant and usually present for evaluation within several hours to days of onset of symptoms. Change in bowel habits are also frequent with obstipation being most frequently cited. Bloating, nausea, vomiting and anorexia may be seen due to an associated small bowel ileus.   Many patients may also have a low grade fever. Laboratory examination is often non-specific with leukocytosis being commonly seen.
Radiographic examination is useful for confirming clinical suspicion. The radiographic procedure of choice is a computed tomography (CT) scan of the abdomen and pelvis with intravenous contrast. Typical findings include observation of sigmoid diverticula, peri-sigmoid inflammatory changes, extraluminal gas or fluid or pericolic abscess. Adjacent organ involvement may also be seen. It is important to remember that CT scan only confirms segmental colitis and is not entirely diagnostic as other conditions such as perforated malignancy, ischemia or inflammatory bowel disease can give a similar radiographic appearance. Other radiographic imaging techniques such as plain abdominal films and ultrasound are often non-diagnostic. Lower GI contrast studies are likewise often non-specific and could potentially be harmful. Endoscopic examination can be useful to exclude other etiologies if clinical suspicion suggests an etiology other that diverticulitis.
Clinical classification of the severity of diverticular disease can help guide therapeutic decisions. The Hinchey classification is most commonly described. Hinchey class I disease is localized pericolic inflammation, class II is localized pericolic abscess, class III is diffuse purulent peritonitis and class IV is diffuse feculent peritonitis. Patients Hinchey class I-III inflammatory complications can often be managed non-operatively with or without percutaneous drainage of localized sepsis. Hinchey class IV patients often require urgent surgical therapy.
Patients with acute diverticulitis are often seen urgently in the outpatient clinic or Emergency Department. Decisions regarding the need for inpatient vs. outpatient care should be individualized and based on the severity of the patient’s complaints. Patients with Hinchey class I disease that can tolerate oral intake, have well controlled pain and no inflammatory or radiographic indices suggestive of more complicated disease can be managed as an outpatient with oral antibiotics and close follow up in the outpatient clinic. Antibiotic therapy should be directed at typical lower GI flora. For patients not meeting these criteria inpatient care is required with bowel rest and intravenous fluids and antibiotics. Appropriate therapy usually results in prompt resolution of the symptoms and a resumption of normal bowel function in the majority of patients. After complete resolution of the acute process (4-6 weeks) patients should undergo colonoscopy to exclude other etiologies of the inflammatory process. Rarely, patients will develop non-resolving symptoms either in the hospital or the outpatient setting and should be considered for segmental resection.
Patients with Hinchey II or III inflammatory complications can rarely be managed as an outpatient and most commonly require inpatient care similar to that previously described. Small pericolic abscesses (<2 cm) and intra-mural abscesses may resolve without intervention. Larger abscesses will typically require percutaneous drainage and with the skill of today’s radiologists it is uncommon that this approach can not be undertaken. This approach will often “defuse” the acute situation and obviate the need for urgent surgical intervention in the majority of cases. Again, with appropriate medical and interventional care prompt acute symptom resolution is the norm. Historically, patients with more advanced inflammatory complications were offered elective resection once the inflammatory process had resolved. Newer data challenges this dogma and it is felt by many that if complete resolution of the acute inflammatory process occurs and the patient is asymptomatic, elective resection can be avoided with a low risk of recurrence and/or complications. Patients that do no satisfy this requirement should still be offered elective resection after resolution of the acute process.
Patients with acutely non-resolving symptoms in the setting of Hinchey class I-III inflammation and patients with Hinchey class IV disease should be offered urgent surgery. Three stage approaches to resection is mentioned for historical purposes and is generally not acceptable due to the high infectious complications resulting in substantial morbidity and mortality. A two stage approach with resection of the inflamed segment and preservation of the surrounding structures is generally the standard of care. The proximal and distal extent of resection should extend to healthy, normal colon and rectum. This can take the form of Hartmann’s resection with creation of an end colostomy and rectal stump closure or primary colorectal anastomosis with protecting loop ileostomy. The latter has obvious advantages but is not always technically possible. Recent reports have advocated primary unprotected colorectal anastomoses in patients undergoing acute surgery for complicated diverticular disease. The decision to proceed with this approach should be carefully considered and used in only the most ideal circumstances.
Chronic complications of diverticular disease
In addition to acute inflammatory complications, chronic complications of sigmoid diverticulitis are common and include stricture, fistula and recurrent inflammation. 
Strictures of the colon result from chronic inflammation and fixed scarring resulting in luminal compromise. Acute, complete obstruction is uncommon and patients typically present with chronic partial obstructive symptoms. Symptomatic patients should undergo radiographic and endoscopic evaluation to exclude a malignant process and then be offered elective resection.
Fistulas complicating diverticular disease are often associated with the genitourinary tract and generally require surgical therapy. Colocutaneous fistulas are uncommon and can be seen complicating percutaneous drainage tracts. In men colovesicle fistulas are often seen and are typically heralded by pneumaturia and recurrent urinary tract infections. CT scan is the diagnostic procedure of choice with the finding of air within the non-instrumented bladder being diagnostic. Women generally develop colovaginal fistulas and often only in the setting of a prior hysterectomy. Symptoms are typically passage of flatus or stool per vagina, recurrent vaginitis or urinary tract infections. Careful physical examination and radiographic imaging (CT scan) is diagnostic. In both cases, segmental resection of the sigmoid colon, division of the fistula and primary anastomosis is curative. There is no need for bladder or vaginal repair. The bladder should be drained for several days (5-7 days) to prevent urine leakage.
Recurrent disease is less common than previously thought. Traditionally, recurrence rates after an uncomplicated initial episode were variably reported as 30-50%. Newer data suggests that the recurrence rate is lower varying from 5-20% with recurrences tending to mimic the severity of the initial attack. In patients requiring urgent surgery it is the initial attack in over 80% of cases. With this in mind the argument in favor of surgical therapy in cases of recurrent disease, which is recurrence is inevitable and that subsequent attacks may be more complicated, seem less sure. The exact indications for surgery in recurrent diverticular disease remain under discussion but the trend seems to be more in favor of non-operative therapy and individualizing surgery for this particular indication. Recurrent disease does appear to be more prevalent in younger patients although the natural history of diverticulitis and recommendations for surgical therapy in this group remain controversial.
Acute diverticulitis complicating chronic immune suppressed states is becoming increasingly common. Patients suffering acute diverticulitis in the setting of chronic renal insufficiency, transplant immunosuppression or cancer chemotherapy tends to present with more advanced disease and be less able to be managed non-operatively in both the acute and chronic setting. 
Laparoscopic vs. Open resection for sigmoid diverticulitis
The exact role and benefits of laparoscopy in elective resection for sigmoid diverticulitis is undetermined and associated with passionate debate. Clearly, laparoscopy can be performed safely and is associated with nominal benefits in terms of length of stay, less pain and quicker recovery. That being said it continues in most centers to be associated with longer operative times and more operative cost. Most would agree that for an experienced laparoscopic surgeon with an adequate case volume to maintain laparoscopic skills this is an acceptable alternative to open surgery. The benefits of laparoscopic colectomy however are not such that it should be used by lower volume surgeons or those not facile with advanced laparoscopic techniques.
Surgical specialization and outcomes in sigmoid diverticulitis
Surgical specialization and regionalization of complicated surgical procedures engenders heated debate. A clear benefit to colorectal sub-specialization in surgical outcomes of complicated diverticulitis has been shown. A number of articles have also demonstrated the difficulty of adopting advanced laparoscopy for lower volume surgeons. As the surgical quality debate moves forward these types of outcome studies and the difficult realization that surgical sub-specialization is required for certain procedures will likely become more prominent. 
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