Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice (50 page)
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Authors: Simon Paterson-Brown MBBS MPhil MS FRCS
Acute colonic diverticulitis
Colonic diverticula are found with increasing age. It has been estimated that one-third of the population will have colonic diverticula by the age of 50 years and two-thirds after 80 years. Although the vast majority of individuals with colonic diverticula are asymptomatic, most patients who require surgical care do so because of an inflammatory complication. Acute diverticulitis can affect any part of the colon; in Western Europe and North America, the left side is more commonly affected, whereas in Japan and China right-sided diverticulitis is more commonly seen. Symptomatic complications of diverticulitis occur in 10–30% of patients, but the need for surgery in acute diverticulitis is becoming less common.
Diverticulitis is thought to result from inspissation of stool in the neck of a diverticulum, with consequent inflammation and possible microperforation. This results in local bacterial proliferation, leading to inflammation in the surrounding colonic wall and mesentery (acute phlegmonous diverticulitis). A collection of pus may form either in the mesentery of the colon or adjacent to the colonic wall. As the collection of pus enlarges, it becomes walled off by loops of small bowel or the peritoneum of the pelvis. Occasionally, free perforation into the peritoneal cavity occurs with consequent purulent or faecal peritonitis. The Hinchey grading system for acute diverticulitis has become fairly widely accepted, allowing more meaningful comparison between outcome studies (
Table 10.1
).
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Table 10.1
Hinchey classification of peritoneal contamination in diverticulitis
| Stage 1 | Pericolic or mesenteric abscess |
| Stage 2 | Walled-off pelvic abscess |
| Stage 3 | Generalised purulent peritonitis |
| Stage 4 | Generalised faecal peritonitis |
From time to time other complications also arise. A fistula sometimes develops between bowel and another adjacent organ (ie. the bladder or vaginal cuff). Diverticular disease is responsible for around 10% of all cases of left-sided large-bowel obstruction and is frequently difficult to differentiate from malignant left-sided large-bowel obstruction on clinical grounds. Bleeding also occurs.
There has been controversy regarding the virulence of diverticular disease in younger patients and the possible increase in need for surgical intervention in this group. Recently, Biondo et al. looked at 327 patients treated for acute left colonic diverticulitis and compared those aged 50 or less with those older than 50.
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No difference was noted regarding severity or recurrence. Another study found that diverticulitis in the young does not follow a particularly aggressive course.
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In general, there is a trend towards conservative management of acute diverticulitis, with early investigation and confirmation of the diagnosis being a fundamental part of this approach. The mortality and morbidity rates can be high if emergency surgery is necessary.
Acute right-sided diverticulitis, a rare condition in the Western world, can be confused with appendicitis as it occurs in a somewhat younger age group than left-sided disease. In the more common left-sided disease, the plain abdominal radiograph may show non-specific abnormalities such as pneumoperitoneum, intestinal obstruction or a soft-tissue mass.
CT is now the favoured modality for acute investigation of suspected acute colonic diverticultis.
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Features of acute diverticulitis include thickening of the bowel wall, increased soft-tissue density within the pericolic fat secondary to inflammation and a soft-tissue mass, which represents either a phlegmon or an abscess. Advantages of CT include the accurate assessment of the extent of pericolonic involvement and the diagnosis of abscess formation or perforation (
Fig. 10.10
). It is also useful for tracking the therapeutic percutaneous drainage of any abscess. When CT is compared with barium enema, CT is no more accurate in terms of diagnosis but undoubtedly provides better definition of the extent and severity of the inflammatory process, which is of prognostic value in the short and long term.
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Ultrasonography has also been used for localised diverticulitis. The main disadvantages of ultrasonography are that assessment of bowel thickening is a non-specific finding and assessment is very operator dependent.
Figure 10.10
Appearance of perforated sigmoid diverticular disease on CT. The upper arrow shows a small pocket of free air and the lower arrow one of the diverticula.
An alternative investigation is contrast enema. Despite the extensive literature on the use of contrast enema in acute diverticulitis, there is no consensus on either the best contrast agent or the optimal timing of the examination. There has been some interest with magnetic resonance imaging in the diagnosis of acute diverticulitis and prospective observational studies have been encouraging, but more formal evaluation is still required.
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Right-sided disease may be encountered unexpectedly at surgery or be operated on for a complication diagnosed preoperatively. The treatment options are controversial, ranging from appendicectomy to hemicolectomy. A conservative approach with appendicectomy and antibiotics has resulted in a similar mortality, morbidity and recurrence as for resection of the diverticulum.
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A right hemicolectomy is the correct operation when it is not possible to rule out the presence of a carcinoma.
A typical patient with localised left-sided diverticulitis will complain of pain in the left iliac fossa and will be febrile. Examination reveals tenderness and sometimes a mass is palpable per abdomen or on rectal examination. In women, a vaginal examination should also be performed to exclude gynaecological pathology. If sigmoidoscopy is performed, it should be done gently with minimal insufflation of air.
In the absence of generalised peritonitis, a non-operative policy is adopted, with antibiotic therapy directed against Gram-negative and anaerobic bacteria. Most clinicians advocate bowel rest initially, and intravenous fluids and antibiotics. If the pain and fever settle within a few days, the patient can go home on oral antibiotics and a barium enema and sigmoidoscopy or colonoscopy can be performed as an outpatient several weeks later to exclude any malignancy.
If the patient continues with fever, pain or enlarging lower abdominal mass, a CT should be obtained. If there is an abscess, it can be drained percutaneously under radiological guidance. In the event of localised abdominal signs becoming more generalised, or if there is a failure of the infective process to settle despite adequate non-operative therapy, operation is indicated. In the small number of patients who require operation for localised diverticulitis, primary resection, with or without on-table irrigation and primary anastomosis, is becoming increasingly popular among specialist colorectal surgeons.
Pain from perforated sigmoid diverticulitis usually commences in the lower abdomen, mostly on the left side, and gradually spreads throughout the abdomen. In 25% of patients, however, signs and symptoms are predominantly right-sided
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and in some patients might mimic acute appendicitis. On examination, there are signs of generalised peritonitis including guarding and rebound tenderness. About one-quarter of all patients will have free gas under the diaphragm on plain radiography, and at operation purulent peritonitis is more common than faecal peritonitis.
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The majority of patients presenting in this way will clearly require operation following adequate resuscitation. Antibiotic therapy should be commenced early to cover both anaerobic organisms and Gram-negative bacteria. Some patients will improve so much with non-operative treatment that it may be appropriate to continue with this therapy for a longer period.
Operative management:
The patient is placed in the lithotomy/Trendelenburg position and explored with a midline incision. Pus and faecal material should be removed from the peritoneal cavity and specimens sent for microscopy and both aerobic and anaerobic culture. Intraoperative irrigation of the peritoneal cavity with 6–10 L of warm saline solution is of value, while the addition of topical antibiotics to the solution (e.g. cephradine 1 g in 1 L of 0.9% saline), although logical, remains unproven.
In addition to treating the peritonitis, surgical treatment must minimise continued contamination of the peritoneal cavity. A review of 57 reports
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on the treatment of acute diverticular disease demonstrated that the operative mortality rates from procedures that involve primary resection (10%) were less than half those from operations that did not include excision of the diseased colon (20%). A further reason for advocating primary resection is the difficulty experienced at the time of operation in deciding whether the lesion is a perforated carcinoma or an area of diverticulitis. At laparotomy, the appearance of both lesions may be similar when the colon is inflamed and oedematous. It has been estimated that as many as 25% of patients with a preoperative diagnosis of perforated diverticulitis may be found to have a perforated carcinoma. If there is reasonable suspicion of carcinoma, a radical resection of the lesion, together with the colonic mesentery, needs to be performed. Examination of the resected specimen at the earliest opportunity is recommended to aid further decision-making.
Failure to take the resection far enough distally beyond the sigmoid colon risks recurrence of diverticular disease. Therefore, Hartmann's resection with complete excision of the sigmoid and closure of the rectum, with formation of a left lower quadrant colostomy, has been the standard procedure advocated by most surgeons. If the operation is exceptionally difficult owing to the colon being very adherent to surrounding structures, making safe mobilisation impossible, it may be reasonable to create a proximal stoma, drain the area and transfer the patient to a tertiary referral centre for more definitive treatment.
There has been an increase in the use of primary anastomosis in selected patients who have operations for acute diverticulitis. The main reasons are: (i) that patients receive one operation rather than two; (ii) after a Hartmann operation many patients are left with a permanent stoma, either because of unwillingness or unfitness to have further surgery; and (iii) reversal operation after Hartmann's resection can be very difficult.
One study reported resection, intraoperative colonic lavage and primary anastomosis in 55 of 124 patients with complicated diverticular disease; 49 of the 55 had diverticulitis, 33 having localised and 16 generalised peritonitis.
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Faecal peritonitis was considered a contraindication to a one-stage procedure. Four patients died, one from an anastomotic leak. Major complications included two anastomotic leaks (one of which was successfully treated with parenteral nutrition), four re-operations (three for abdominal wound dehiscence and one for anastomotic leak) and four deaths (three of those who died were over 70 years old). The study concluded that one-stage resection is feasible in selected patients.
One-stage resection for acute complicated diverticultis without faecal peritonitis is feasible and should be considered, depending on patient fitness.
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A further study of primary anastomosis in emergency colorectal surgery showed no significant difference in the incidence of complications, even in patients with free peritonitis (21.9% perforation, 17.7% localised sepsis).
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The necessity for intraoperative colonic lavage has also been challenged. Despite an increasing trend to perform primary anastomosis in patients who have perforated diverticulitis, the number of patients who are suitable for such a procedure will be small.
Laparoscopic techniques continue to be used in an increasing number of diverticular cases with good results,
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with laparoscopic assessment and lavage also a possibility. A recent review found laparoscopic peritoneal lavage for perforated sigmoid diverticulitis to be a potentially effective and more conservative alternative to a Hartmann procedure.
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Randomised controlled trials are needed to better evaluate its role.