Acute Diverticulutis

Jasiah Zakaria MS(UKM),
Akhtar Qureshi FRCS(GEN) England
Dept. of Surgery, Hospital Seremban and International Medical University, Seremban, Malaysia.


Introduction
Diverticular disease is generally considered to be a disease of the elderly. By the age of 85 years almost 80% of population will have a diverticular disease (Rodkey). The incidence of diverticular disease in young population appears to be increasing (Eusebio). Generally colonic diverticular disease are true diverticula containing all coats of the mural structure. The estimated incident of diverticular disease in the late 1960s ranged from 2-4% but more recent estimates suggest an incidence of 12-30%. Most of the elderly with diverticular disease remain asymptomatic. Only 10-25% of the affected population with diverticular disease will develop diverticulitis. And only 20 to 30% of those with diverticulitis will require surgical intervention (Park). Diverticulitis in young population is a distinct entity, frequently posing a problem in diagnosis. The virulent nature of diverticulitis in young patient has been described, and surgical intervention is needed in up to 70% of these patients (Konvolinka).

Distribution of diverticular disease is significantly different between western community and Far East. There is predominance of right colon involvement in Far East (Japan, Hong Kong and Malaysia) in contrast of the left colon in the Caucasians (Chan, Mira Chia, Saggap). Right sided diverticular disease occurs in the ascending colon and caecum, and is not uncommonly solitary in nature.

Pathogenesis
The cause of colonic diverticular disease is related to two main factors, increased intraluminal pressure and weakening of the bowel wall (Truelove). Diminished stool bulk from insufficient dietary fiber, leads to alterations in gastrointestinal transit time and to elevated colonic pressure, others have identified an increased red meat intake in right sided colonic diverticular disease. Patient with colonic diverticular disease have elevated resting colonic pressures and more frequent high-pressure waves (Arfwidsson). Hypersegmentation and increased intracolonic pressure cause hernialion of the colonic mucosa at areas of weakening adjacent to the points of penetration of the vasa recta through the bowel wall (Painter). Diverticular, therefore tend to be arranged in rows, situated between the mesenteric and lateral tenia coli (Truelove). Particles of undigested food may become inspissated within the colonic diverticulae. Obstruction of the neck of a diverticular then cause distension as a result of mucus secretion and overgrowth of normal colonic bacteria. The thin-wall diverticula's, consisting solely of mucosa, is thus highly susceptible to vascular compromise and subsequent perforation. Many of diverticulae are adjacent to or within the mesocolon or appendices epiploicae, the walling of and localization of the perforation are common.

Clinical diverticulitis virtually always represents a microperforation and further demonstrates that the colonic mucosa is grossly and microscopically normal, despite considerable inflammation of the pericolonic tissue (Fleischer). The submucosa of the large bowel plays an important role in maintaining the integrity of colonic wall. The viscoelastic properties of collagen give the colon its expandability and strength. The structural changes to the collagen tissue of affected colon are similar to those that occur as part of aging process but are at greater rate (Wess). A prospective cohort study done by Aldoori suggests that increasing levels of physical activity reduces the risk of symptomatic diverticular disease. Combination of low physical activity and a low-fiber diet augments the risk.

Clinical Presentation
The clinical diagnosis of acute colonic diverticulitis is suggestive in patients presenting with abdominal pain which usually begins in the hypogastrium then localizing to left lower quadrant ("left sided appendicitis"), or as in Malaysia, a clinical picture of acute appendicitis. There may be alteration in bowel habits such as diarrhoea or constipation. Other symptoms such as dysuria, frequency and urgency may result if the affected colonic segment lies close to urinary tract. Pneumaturia, fecaluria or recurrent urinary tract infections may be present if a colovesical fistula is present. Occasionally, these patients have referred pain to the suprapubic region, penis and scrotum (Hafner).

On physical examination, tenderness is usually localized to the left lower quadrant. A lower abdominal mass or rectal mass may be present. Traces of blood in stool may be present but massive lower GIT bleeding is extremely rare in acute colonic diverticulitis. Generalized peritonitis occurs secondary to a rupture of a peridiverticular abscess or free rupture of an uninflammed diverticulum. Colonic obstruction is uncommon. Small bowel obstruction occurs more frequently in the presence of a large peridiverticular abscess. Though 85% of cases of diverticulitis occur in the sigmoid and descending colon, diverticula may be found throughout colon. Right sided diverticulitis occurs more frequently in Asians (Miura) and tend to mimic appendicitis as it occurs at younger age than that of left-sided colonic diverticulitis (Cunningham, Magness).

Investigations
Colonic diverticular disease is easily diagnosed by double contrast barium enema, but their presence alone does not establish the presence of diverticulitis. Multiple diverticulae along with segmental sigmoid narrowing or extravasations of contrast material suggest presence of diverticulitis or Crohn's disease. There is a relatively poor correlation between radiologic and subsequent pathological diagnosis of acute diverticulitis.

Computed tomography (CT) and ultrasonography are useful to diagnose diverticulitis. CT scan is the safest and the most cost-effective diagnostic method, with potential therapeutic use in treatment of abscess (Siewert). CT scan evidence of acute diverticutitis includes inflammation of the pericolic fat, presence of a single or multiple diverticular, thickening of the bowel wall to more than 4mm, or the finding of a peridiverticular abscess (Hulnick). CT scan is also able to visualize the bowel wall and enlarged pericolic nodes as well as to exclude other intra-abdominal pathology. CT scan guided percutaneous drainage can control sepsis and eliminate or reduce the size of abscess.

Ultrasonography can be used in the diagnosis and treatment of acute diverticulitis. A positive ultrasound finding includes a hypoechoic, thickened colonic wall, presence of diverticula, pain on compression of the affected region, and a zone of increased echogenicity surrounding the diseased colon (Schwerk, Chou). It is inexpensive, noninvasive and widely available but is more operator-dependent compared to a CT scan. The image quality is often poor in obese patients. CT scan and sonography frequently fail to distinguish between inflammatory and neoplastic lesions (Zieike). Despite these problems CT scan remains the diagnostic method of choice in acute diverticulitis.

Treatment
Treatment of acute colonic diverticulitis depends on the stage of the disease. Clinical staging by Hinchey's classification:

Stage
  
I
 Pericolic or mesenteric abscess
II
 Walled-off pelvic abscess
III
 The presence of generalized peritonitis with pus
IV
 Generalized peritonitis with faeces

The pathological staging as follows: (Belmonte)

Stage
  
0
 No Inflammation
I
 Chronic inflammation
II
 Acute inflammation with or without micro abscesses
III
 Pericolonic or mesenteric abscess
IV
 Pelvic abscess
V
 Purulent or feculent peritonitis

Once a patient is diagnosed to have acute colonic diverticulitis by clinical examination, empirical treatment should be started with a broad-spectrum antibiotic including coverage for anaerobic microorganism (cephalosporin and metronidazole) for 7-10 days. In mild cases where the patient is able to tolerate orally, an out patient treatment may be possible with oral antibiotics. Once the acute attack is resolved, the patient is advice to maintain a high fiber diet and colonoscopy performed to exclude the possibility of colonic malignancy. (Brodribb)

If the patient is unable to tolerate orally, has severe pain or deteriorating symptoms, then admission to a hospital is necessary. The patient is kept nil by mouth, intravenous broad-spectrum antibiotics are administered and bed rest advised. Standard antibiotics consist of a cephalosporin and metronidazole. If symptoms do not improve within two to three days, or if the patient has persistent pain, spiking fever, persistent leukocytosis or evidence of peritonitis either local or generalized further imaging studies are indicated. CT scan is able to confirmed peridiverticular or pelvic abscesses. Small abscesses, mostly regress with treatment and the patient is advised a single-stage resection. If the abscess size is greater than 5cm radiological assisted percutanous drainage as initial therapeutic approach has been advocated (Neff). About 70% of elderly patients who have a single uncomplicated episode of diverticulitis will have no further recurrence (Park) and hence, can be treated medically. Unfortunately in young patients recurrence is high and ranges from 50% (Eusebio) up to 100% (Cunningham). Approximate 20% of elderly patients with diverticulitis will require surgical intervention as compared to patient < 40 years old, where surgical intervention is required in as many as 70-86%. Acute colonic diverticulitis in young patients is a distinct entity and a more virulent form of diverticulitis than found in the elderly. Surgical resection is the best treatment for diverticulitis in patients under 40 years of age (Cunningham). The indications for emergency colonic resection includes generalized peritonitis, uncontrolled sepsis, visceral perforation and acute clinical deterioration.

The primary goal of surgery for colonic diverticular disease is to remove the affected bowel with minimal morbidity and mortality. Maintaining or restoration of bowel continuity is an important but secondary goal.

Surgical treatment can be summarized into: -

1. Three-stage procedure
This should be abandoned due to the associated high morbidity and mortality rate. Historically, this option was performed in all cases of diverticular abscess with rupture, in cases of gross fecal peritonitis and colonic obstruction. The initial operation was drainage of the abscess and a colostomy, the second procedure was resection of affected colon and finally bowel continuity was restored by colostomy closure.

2. Hartmann's procedure
By the early 1980s a two-stage operation had become popular as the affected bowel is eliminated by resection and there is no anastomosis to leak. The main problem was restoration of continuity after Hartmann's operation due to procedure being technically difficult with high rate of morbidity up to 16% and mortality up to 4% (Belmonte). The morbidity, mortality and length of hospitalization associated with closure of colostomy are additive to the primary procedure especially those who had general peritonitis (Auquste). Hartman's procedure leaves a considerable number of patients, up to 1/3 with disability of a permanent colostomy (Wedell, Maddern).

3. Resection and primary anastomosis
The third option is resection of the affected segment of the bowel and primary reanastomosis with or without a defunctioning loop colostomy or loop ileostomy. The rationale for anastomosis and proximal diversion instead of the Hartman procedure is to avoid subsequent operation in the pelvis and their inherent associated difficulties. The method of fecal diversion is an individual choice. Loop ileostomy was preferred due to ease of performance, ease of closure and reduced morbidity and mortality. Gregg first reported the concept of resection and primary anastomosis in 1955. Since then several authors have reported their experiences. Selection of cases was very important; resection and primary anastomosis can be performed for patients at stage 0,1,11,111 with minimal mortality, and morbidity up to 20% with anastomotic leak 2% (Belmonte). The mortality and morbidity is higher for stages IV and V and thus selection is important. Majority of the patients, up to 80% underwent an elective operation. Firstly, the patient is resuscitated, proper bowel preparation and a planned operation by an experience operating team. Factors to be weighed when considering primary anastomosis in pelvic sepsis include: -

• The condition of the patient which includes presence or absence of shock, associated co morbid conditions, age and urgency of procedure.

• The condition of the bowel which includes adequacy of blood supply, presence of edema and quality of bowel preparation.

• The experience of the operating team as primary anatomosis in the presence of complicated diverticular disease requires sound judgment and a technically perfect operation.

Patients with localized inflammation only, including contained purulence and most patients with fistula can be managed with resection and primary anatomosis without diversion. Patients with large pelvic abscess should be managed in a selective fashion. Percutanous drainage of abscess has been advised to convert clinical status from an emergency to elective one. Unfortunately, 27% of patients who undergo surgical intervention will continue to have some symptoms (Munson).

In patients with caecal diverticulitis, noted through a Lanz incision, the diagnosis can be made by palpating a thickened area of the caecum, and can usually be left alone, having performed an appendicectomy, with intravenous antibiotics (Lim). Where a carcinoma cannot be excluded, a right hemicolectomy is advised.

Complications of Diverticulitis

Abscess
An abscess results when there is perforation of a colonic diverticulum. A localized phlegmon develops when there is limited spread of the inflammation, while larger spread can lead to the formation of larger local or distant abscesses. CT scan is the best modality to make the definite diagnosis of an abscess and to follow its course over time and is also valuable as a guide for percutaneous drainage. Microabscesses can usually be treated by antibiotics, however larger abscesses require some form of drainage and less commonly surgical resection of the affected segment of the bowel (Ambrosetti).

Fistulas
Rupture of the associated abscess into an adjacent organ results in a fistula. The most common being the bladder with a male preponderance and vagina in patients post hysterectomy (Stollman). Coloenteric, colouterine, and coloureteral fistulas occur less commonly. Spontaneous colocutaneous fistulas are very rare and more frequently follow prior surgical repair.

Obstruction
The most common type of bowel obstruction in acute diverticulitis is small bowel obstruction, when a loop of ileum is incorporated into the inflammatory mass. The process improves with reduction in the inflammation. Colonic obstruction in acute diverticulitis is rare. Recurrent attacks of acute diverticulitis can lead to stricture formation.

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