Management of complicated diverticulitis of the colon

Abstract Diverticular disease of the colon occurs quite frequently in developed countries, and its prevalence has recently increased in Japan. The appearance of diverticulosis increases with age, although mostly remaining asymptomatic. Approximately 20% of cases require treatment. As the Western lifestyle and number of elderly people increase, the need for medical treatment also increases. Computed tomography (CT) is the gold standard for diagnosing diverticulitis. Complicated diverticulitis is classified by the size and range of abscess formation and the severity of the peritonitis. Each case should be classified based on clinical and computed tomography (CT) findings and then treated appropriately. Most patients with uncomplicated diverticulitis (stages 0–Ia) can be treated conservatively. Diverticulitis with a localized abscess (stages Ib–II) is generally resolved with conservative treatment. If the abscess is larger or conservative treatment fails, however, percutaneous drainage or surgery should be considered. Operative treatment is considered standard therapy for severe diverticulitis with perforation and generalized peritonitis (stages III–IV). Colonic diverticulitis treated conservatively frequently recurs. Elective surgery after recovery should be considered carefully and decisions made on a case‐by‐case basis. Because cases of colonic diverticulitis will undoubtedly increase in Japan, it is likely that we will be confronted with increasing numbers of treatment decisions. We therefore need to have a systematic strategy for treating the various stages of colonic diverticulitis appropriately. We herein review the management of complicated diverticulitis.

There is a difference in the localization of diverticula between Western and Asian countries. Colonic diverticula are found in the sigmoid colon in >90% of patients in Western countries, whereas the right-sided type is found in about 70% of the patients in Japan. 6 A multi-institutional study in Japan revealed that the right-sided type accounted for 69.3%, the bilateral type for 16.8%, and the left-sided type for 13.9%. There is a high frequency of the right-sided type during middle age, whereas the left-sided and bilateral types increase with age, with about half occurring in people >70 years. 7 Approximately 75-80% of patients with anatomical diverticulosis remain asymptomatic throughout their lifetime. For the other approximately 20% of patients with diverticulosis who develop diverticulitis, 1 1-2% require hospitalization, and 0.5% require surgery because of complications such as an abscess or peritonitis. 8 Herein, we review the management of complicated diverticulitis.

| DIAGNOSIS
For patients in whom complicated diverticulitis is suspected, the precise diagnosis requires cross-sectional imaging such as computed tomography (CT). 9 With its reported 93-97% sensitivity and 100% specificity, CT has evolved as the gold standard diagnostic test for suspected diverticulitis. 10,11 CT is minimally invasive, rapid, and widely available. It is not only useful for diagnosis, but also for the observation of changes over time. 12 It provides details regarding the size and location of an abscess, providing an objective analysis of the severity of the diverticulitis. Treatment decisions can then be made based on CT scans. Ultrasonography serves as another good diagnostic tool and may supplement the information obtained from CT, 13,14 although its usefulness depends on the experience of the examiner. 15

| Stages 0-Ia
More than 70% of patients with acute diverticulitis display no evidence of an abscess or perforation. 18

| Stages III-IV
Approximately 6% of patients develop severe diverticulitis with perforation and generalized peritonitis ( Figure 4). 18 In the case of Hinchey stage III-IV peritonitis, abdominal CT shows the presence of peritoneal fluid and extraluminal air. Clinically, symptoms of peritonitis (eg rebound tenderness, muscular defense) are found. Peritonitis is the most life-threatening complication, with 14% mortality. 24 Operative treatment is considered standard therapy for patients with Hinchey stage III or IV diverticulitis. During the 1980s, Hartmann's procedure became the standard, and it is still widely practiced today. It is a two-stage procedure involving resection of the diseased colon, closure of the distal rectal stump, and construction of an end-colostomy. At the second stage, the colostomy is reversed. However, Hartmann's reversal, or stoma closure with reconstruction, may be difficult. It has been reported that the ostomy could not be closed in 30-40% of cases owing to the high surgical risk in older patients with many comorbidities. 26,27 During the 1990s, one-stage surgery was reported for patients in good general condition. It comprised primary resection with anastomosis, with or without protective ileostomy or colostomy. 28 Recently, the safety and effectiveness of laparoscopic surgery for complicated diverticulitis has been reported. There was no mortality or serious complications directly related to the laparoscopic procedure, and laparoscopic colonic resection for Hinchey stage I-II diverticulitis is at least as safe and effective as traditional open surgery. 29 However, laparoscopic treatment of diverticulitis is technically challenging and requires adequate training and experience. 30 The use of laparoscopic surgery for the emergency treatment of complicated diverticulitis is still controversial. 31 The laparoscopic treatment of complicated diverticulitis has evolved and changed over the last dec- There is no place today for laparoscopic resection for Hinchey stage III or IV disease. 9 The usefulness of laparoscopic lavage without resection for complicated diverticulitis was reported, after which randomized, controlled trials were conducted. Laparoscopic lavage versus primary resection, however, did not reduce the incidence of severe postoperative complications and led to worse outcomes. For patients with Hinchey stage III disease, the superiority of laparoscopic lavage compared with colectomy is not proven, and rather serious complications were reported. 34 The rate of reintervention within 30 days postoperatively was 28.3% in the lavage group and 8.8% in the resection group. Despite this risk, one of the major proposed advantages of laparoscopic lavage is avoidance of a stoma. Laparoscopic lavage leads to more reinterventions, but does not increase the Currently, the standard procedure is Hartmann's operation or primary anastomosis with or without a diverting ileostomy or colostomy ( Figure 5).

| RECURRENCE
When colonic diverticulitis is treated conservatively, the overall recurrence rate is reported to be 18.1%, and the mean interval to the onset of the recurrence is 4.7 AE 5.9 months. 18 There is a tendency towards an escalating recurrence risk with an increasing number of recurrences. Recurrence risk more than doubled after one previous episode and increased gradually related to the number of recurrences. 36 Recurrent episodes of diverticulitis mostly have a benign course.
Only 5.5% of patients with hospitalizations for recurrent diverticulitis are subjected to emergency surgery. 37 The recurrence of mild diverticulitis is not considered a risk factor for serious complications, such as perforation or abscess formation. 38 According to the guidelines of the The best treatment for recurrent diverticulitis is undetermined.

| CONCLUSION S
The present review summarizes the diagnosis and treatment of patients with acute diverticulitis. Figure 1 summarizes the current diagnostic and therapeutic options for colonic diverticulitis. It is thought that the prevalence of diverticulitis of the colon will increase in Japan in the future, as has occurred in Western countries. Because medical treatment of this entity will also increase, surgeons should be aware of a systematic strategy for treating the various stages of colonic diverticulitis appropriately.
F I G U R E 3 Computed tomography image shows pericolic abscess walled off by colon, mesocolon, bladder and pelvic peritoneum. This is Hinchey stage II. This patient was treated with antibiotics but failed. Sigmoid colon resection was carried out F I G U R E 4 This is Hinchey stage III disease. Computed tomography image shows perforated diverticulitis of sigmoid colon with free air that caused generalized peritonitis. A two-stage procedure, Hartmann's procedure was carried out