Inpatient treatment of acute diverticulitis varies depending upon whether the patient has complicated or uncomplicated disease. Patients with complicated diverticulitis must undergo treatment specific to their complications. All patients undergo treatment for diverticulitis with intravenous antibiotics, fluids, and pain medications.
Initial inpatient care
Inpatient treatment of complications
(1) Perforation
Acute diverticulitis can lead to frank perforation or microperforation in the inflamed colonic segment.
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Frank perforation — Evidenced by free air under the diaphragm with or without extravasation of contrast or fluid, frank perforation of the colon results in diffuse peritonitis from intra-abdominal spread of feculent fluid and bacterial organisms. Acute diverticulitis that presents with frank perforation is life-threatening and mandates emergency surgery [23-26]. (See "Acute colonic diverticulitis: Surgical management", section on 'Free (frank) perforation'.)
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Microperforation — Microperforation, also called contained perforation, is the presence of small amount of air bubbles but no oral contrast outside of the colon on abdominopelvic CT imaging. Most patients who have microperforation should be treated initially with intravenous antibiotics in a fashion that is similar to patients with uncomplicated diverticulitis (see 'Inpatient treatment of diverticulitis' below); the majority of them (94 percent) can be managed nonoperatively [27] but with the following caveats:
● Patients with pericolonic air bubbles only (referred to as Hinchey Ia by some authors) can be managed the same way as those with uncomplicated diverticulitis. The success rate of nonoperative management is from 85 to 99 percent [28,29]. (See 'Inpatient treatment of diverticulitis' below.)
● Patients with pericolonic air bubbles associated with an abscess should be managed according to the abscess. The expected success rate of nonoperative management is lower than that of uncomplicated diverticulitis. (See 'Abscess' below.)
● Patients with a small amount of distant intraperitoneal air bubbles (eg, over the liver, under the diaphragm) or distant retroperitoneal air bubbles require an individualized approach: those with a benign abdominal examination may be managed nonoperatively while those with peritonitis should undergo surgery. In these patients, the success rate of nonoperative management varies from 34 to 93 percent, depending on whether there is an associated abscess or pelvic fluid [5,28,30,31]. (See "Acute colonic diverticulitis: Surgical management", section on 'Free (frank) perforation'.)
(2) Abscess
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Antibiotics are the first-line treatment for all diverticular abscesses. (See 'Intravenous antibiotics' below.)
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Percutaneous drainage may be added, if feasible, for abscesses ≥4 cm, those that do not resolve with antibiotic therapy, or in the presence of clinical deterioration. (See 'Large abscess (≥4 cm)' below.)
The guidelines from the American Society of Colon and Rectal Surgeons (ASCRS) also advocate a stepwise approach to treating diverticular abscesses but with a different cutoff size of 3 cm for recommending percutaneous drainage [10]. This discrepancy may not be clinically significant.
비수술적 치료 성공 후 재발률은 15~25%이며 [32,34] 농양이 5cm가 넘으면 재발률이 더 높아진다 [35]. Whether all asymptomatic patients with a healed diverticular abscess require elective surgery is controversial and discussed elsewhere. (See "Acute colonic diverticulitis: Surgical management", section on 'Healed diverticular abscess'.)
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Small abscess (<4 cm) — For smaller abscesses, antibiotic therapy alone and percutaneous drainage have similar success rates, morbidity, and mortality [32]. One study that treated 23 abscesses <3 cm with antibiotics alone reported a treatment failure rate of 0 percent [33]. In another study, 93 of 107 diverticular abscesses <4 cm were successfully treated with antibiotics alone [36].
Patients who respond to antibiotics are followed with serial CT scans until the resolution of the abscess; patients who deteriorate or fail to improve after two to three days of antibiotic therapy may require surgery if percutaneous drainage is not an option.
Abscesses may not be amenable to percutaneous drainage because they are too small (ie, <2 cm) or there are important structures (eg, small bowel) adjacent to them that preclude percutaneous access [33,35,37].
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Large abscess (≥4 cm) — The benefit of percutaneous drainage is greater for larger abscesses than for smaller ones. As the size of the abscess increases from ≤3 cm to 3 to 10 cm and 3 to 18 cm, the success rate of antibiotics-alone therapy decreases from 100 to 82 and 66 percent [32]. By contrast, 80 percent of diverticular abscesses >4 cm resolve after percutaneous drainage [20]. In order to maximize the success rate of nonoperative management, we suggest percutaneous drainage of diverticular abscesses ≥4 cm, whenever feasible, in additional to antibiotic therapy.
CT-guided drainage is typically performed for abscesses that are amenable to percutaneous drainage. An approach through the anterior abdominal wall is favored for most abscesses, while abscesses deep in the pelvis or obscured by other organs are drained transgluteally. Transrectal or transvaginal approaches to abscess drainage have also been described but are rarely used [38,39]. Once a drainage catheter is placed, it is left until the output is minimal, a process which can take as long as 30 days [40].
After percutaneous drainage of a diverticular abscess, patients typically defervesce within 24 to 48 hours. For patients who do not improve within that time frame, surgery is indicated.
3) Obstruction — In patients with suspected colonic obstruction from diverticulitis, radiographic differentiation of acute diverticulitis from colon cancer can be difficult (image 1). Thus, surgical resection of the involved bowel segment is mandatory to relieve the bowel obstruction and rule out cancer. (See "Acute colonic diverticulitis: Surgical management", section on 'Obstruction'.)
4) Fistula — A fistula can develop between the colon and bladder, vagina, uterus, other bowel segments, and abdominal wall. Diverticular fistulas rarely close spontaneously, and a resection of the affected bowel segment is generally required. However, diverticular fistulas do not usually present acutely. The management of a diverticular fistula is discussed separately. (See "Diverticular fistulas".)
Inpatient treatment of diverticulitis
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— Inpatient treatment of acute colonic diverticulitis typically begins with administration of intravenous antibiotics, fluids, and pain medications. Patients can be made nil per os (NPO) to allow for complete bowel rest or be offered a clear liquid diet depending upon their clinical status. Patients without complications typically show a clinical response within two to three days, at which point their diet can be advanced further. Patients who continue to improve are discharged to complete a course of oral antibiotics; those who fail to improve are referred for surgery.
Intravenous antibiotics
— Patients requiring hospitalization should begin intravenous antibiotics with activities against gram-negative rods and anaerobic organisms. The choice of agents depends upon the severity of the illness (table 1 and table 2). In rare occasions when acute diverticulitis develops in patients who are already hospitalized or have undergone percutaneous drainage, antibiotic coverage should be broadened to also include nosocomial organisms (table 3). If a culture has been taken at the time of percutaneous abscess drainage or surgery, the antibiotic regimen should be revised based upon susceptibility results. Anaerobic coverage should be continued if polymicrobial infection is identified. Detailed discussion of antibiotic therapy for intra-abdominal infections can be found in another topic. (See "Antimicrobial approach to intra-abdominal infections in adults".)
Intravenous antibiotics should be continued until the inflammation is stabilized, evidenced by resolving abdominal pain and tenderness. This process typically takes three to five days. The patient is then transitioned to oral antibiotics (most commonly ciprofloxacin plus metronidazole or amoxicillin-clavulanate) to complete a 10 to 14 day course (inclusive of intravenous and oral antibiotic therapy). (See 'Criteria for discharge' below.)
The duration of intravenous antibiotic therapy in patients who undergo procedures for definitive source control (percutaneous abscess drainage or surgery) is discussed separately. (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Duration of therapy'.)
The need for intravenous antibiotics for acute uncomplicated diverticulitis treated as inpatient has been studied in two European trials and one Oceanic trial [41]:
●In the Swedish trial (AVOD), 623 patients with CT-confirmed uncomplicated left-sided diverticulitis were treated with or without antibiotics as inpatients [42]. Complication rates (1.9 versus 1.0 percent), hospital length of stay (three days in both groups), and recurrence rates (16 percent in both groups) were similar. Ten patients initially treated without antibiotics subsequently received antibiotics due to increasing abdominal pain, fever, or increasing C-reactive protein (CRP). A subsequent study, which followed 556 of the original participants for a median of 11 years, reported similar outcomes between the antibiotic and no-antibiotic groups in the rates of recurrences, complications, surgery for diverticulitis, and colorectal cancer [43].
●A second Dutch trial (DIABOLO) randomly assigned 528 patients with first-episode, CT-proven, left-sided acute diverticulitis to observation or 10 days of antibiotics (Augmentin in most, ciprofloxacin plus metronidazole in the rest) [44]. Patients with complicated diverticulitis, with the exception of a small (<5 cm) abscess, were excluded. Most (93 percent) of the trial participants were admitted to the hospital. The median times to recovery without (14 [interquartile range 6 to 35] days) or with antibiotics (12 [7 to 30] days) were similar. At six months, the outcomes were similar in terms of complicated diverticulitis (3.8 percent observation versus 2.6 percent antibiotics), smoldering diverticulitis (7.3 versus 4.1 percent), recurrent diverticulitis (3.4 versus 3 percent), need for sigmoid resection (3.8 versus 2.3 percent), need for readmission (17.6 versus 12.0 percent), adverse events (48.5 versus 54.5 percent), or mortality (1.1 versus 0.4 percent).
●A double-blind, placebo-controlled Australian/New Zealand trial (STANDARD) randomly assigned 180 patients with CT-proven uncomplicated (Hinchey Ia) diverticulitis to either intravenous cefuroxime/Flagyl followed by Augmentin or placebo for seven days [45]. All patients were initially admitted to the hospital. There was no significant difference in hospital stay (40 hours antibiotics versus 46 hours placebo), adverse event rate, or 7 or 30 day readmission rate.
Given that these trials used different exclusion criteria, CT imaging is not perfect in detecting complicated diverticular disease, and most patients admitted for inpatient treatment of acute diverticulitis have either severe disease or serious comorbid conditions, we suggest treating all inpatients with antibiotics rather than selectively based on whether the disease is complicated. This issue remains controversial [46,47], however, particularly between providers based in Europe versus North America [20,22].
Intravenous fluid
— Patients who are admitted for inpatient treatment of acute diverticulitis should be given intravenous fluid (eg, Ringer's lactate or normal saline) to correct volume deficits. Intravenous fluid is typically continued until patients are tolerating adequate liquids.
Pain control — Patients who are admitted for acute diverticulitis often have severe abdominal pain from localized peritonitis. For such patients, parenteral analgesics (eg, acetaminophen, ketorolac, morphine, or hydromorphone) are administered when patients are taking nothing by mouth, while oral analgesics (eg, acetaminophen, ibuprofen, oxycodone) are appropriate when patients are consuming an oral diet.
Inpatient diet — Patients requiring hospitalization can be treated with liquids or complete bowel rest with intravenous hydration, depending upon the severity of symptoms. Patients without complications typically show a clinical response within two to three days, at which point their diet is further advanced.
Subsequent inpatient care
— Patients are assessed daily and typically show improvement after two to three days of antibiotics. Failure to improve should prompt repeat imaging. Patients who show continued improvement can be discharged.
Repeat imaging — Disease progression with or without new complications should be suspected in patients with clinical deterioration and those who fail to improve after two to three days of intravenous antibiotic therapy. Repeat imaging may be required in such patients.
The purpose of repeat imaging, typically with an abdominopelvic CT scan, is to look for new complications (eg, abscess or perforation) that may require further intervention (eg, percutaneous drainage or surgery).
Criteria for discharge — Most patients with uncomplicated diverticulitis have significant clinical improvement after two to three days of intravenous antibiotics. They are then reassessed daily to determine if they are eligible to be discharged from the hospital. The patient must meet all criteria listed below before they can be discharged:
●Normalization of vital signs (ie, resolution of high fever, tachycardia, or hypotension)
●Resolution of severe abdominal pain
●Resolution of significant leukocytosis
●Tolerance of oral diet
Patients are discharged with oral antibiotics to complete a course of 10 to 14 days (inclusive of both intravenous and oral antibiotics). We use one of the following oral antibiotic regimens in adult patients with normal renal and hepatic function:
●Trimethoprim-sulfamethoxazole (1 double-strength tablet [sulfamethoxazole 800 mg; trimethoprim 160 mg] every 12 hours) plus metronidazole (500 mg every 8 hours)
●Amoxicillin-clavulanate (1 tablet [875 mg amoxicillin; 125 mg clavulanic acid] every 8 hours) [48-50] or Augmentin XR (2 tablets [each tablet containing 1 g amoxicillin; 62.5 mg clavulanic acid] every 12 hours)
●Moxifloxacin (400 mg daily; use in patients intolerant of both metronidazole and beta-lactam agents)
The local antibiogram should be consulted to avoid prescribing a regimen to which bacterial resistance exceeds 10 percent. As an example, in areas where the prevalence of Escherichia coli resistance to fluoroquinolones exceeds 10 percent, amoxicillin-clavulanate or trimethoprim-sulfamethoxazole plus metronidazole are the preferred agents. Moxifloxacin is reserved for those who cannot use the other regimens because of high rates of resistance among anaerobes [51]. There is also clinical evidence that fluoroquinolones plus metronidazole were associated with a higher rate of Clostridioides difficile than amoxicillin-clavulanate at one year [52].
After discharge, patients should be reassessed within one week and then weekly until all symptoms have resolved. In a retrospective cohort study of over 200,000 patients, the readmission rate for treatment failure was 6.6 percent, with complicated diverticulitis being the strongest predictor of readmissions [53].
Failure of inpatient medical treatment — Surgery is indicated at any point during admission if the patient's condition deteriorates (eg, increased abdominal pain or leukocytosis, or development of diffuse peritonitis). (See "Acute colonic diverticulitis: Surgical management".)
Patients who fail to improve with two to three days of intravenous antibiotics should undergo repeat imaging to identify new-onset complications of diverticulitis (eg, abscess or perforation). Certain complications may require surgery. (See 'Repeat imaging' above and 'Inpatient treatment of complications' above.)
In addition, surgery may be warranted in patients who fail to improve after another one to two days of medical management, even if no complications are identified with repeat imaging.
