Updated: Aug 24, 2009
Diverticular disease of the colon begins as diverticulosis (colonic outpouchings), which may develop into diverticulitis (diverticular inflammation and perforation).1,2,3,4
Recent studies
Panghaal et al evaluated the CT findings in 14 women who underwent colonic resection for diverticulitis and simultaneous salpingo-oophorectomy, with or without hysterectomy over a 10-year period, for the presence of colosalpingeal fistula. Group 1 included women with a pathologically proven colosalpingeal fistula, and group 2 included those who had contiguous periadnexal inflammation without a fistula. On CT scans, an adnexal collection of gas, either alone or in combination with fluid, was found in 7 patients (88%) in group 1 and in no patients in group 2, resulting in 88% sensitivity and 100% specificity for colosalpingeal fistula. An adnexal collection of fluid alone was found in 1 patient in group 1 and 1 patient in group 2, resulting in sensitivity and specificity of 13% and 83%, respectively.5
Beuran et al studied 46 cases with complicated diverticular disease between 2004 and 2007. There was a male preponderance, and the medium age of patients was 62.9 +/- 15 years. The main complication was perforation, and the sigmoid colon was the most frequent segment involved (71.7%). Failure of conservative measures was the main cause for interventions. According to the authors, CT scanning is the most efficient diagnostic modality.6
For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education article Diverticulosis and Diverticulitis.
Diverticula can be either acquired or congenital, and they can affect either the small intestine or the large intestine. Acquired diverticula are more common and consist of herniation of the mucosa and submucosa through the muscularis, usually at the site of a nutrient artery. Congenital diverticula are outpouchings of the entire thickness of the intestinal wall. The exact mechanism of formation of acquired diverticula is unknown, but they may be related to an increase in intramural pressure. Diverticula usually occur adjacent to the vasa recta, the small vessels that extend into the submucosa, because these are the weakest areas of the colonic wall. Therefore, diverticula usually occur on the mesenteric side of the colon.
Because colonic diverticula are rare in the populations of underdeveloped nations, in contrast to the frequent occurrence in Western countries, theories propose that diverticula result from the highly refined Western diet that is deficient in dietary fiber. This diet results in decreased fecal bulk, narrowing of the colon, and increased intraluminal pressure for moving the smaller fecal mass. The major complications of diverticulosis are diverticulitis and hemorrhage.
Diverticulitis is inflammation in and around a diverticulum. The cause of diverticulitis is probably mechanical. The stagnation of nonsterile inspissated fecal material, termed a fecalith, within the diverticulum may compromise the blood supply to the thin-walled sac and render it susceptible to invasion by colonic bacteria, causing inflammatory erosion of the mucosal lining with perforation. This sequence of events can involve perforation into the colonic wall, with the formation of an intramural abscess. However, perforation usually occurs into the pericolic fat, leading to fibrinous exudate, abscess formation, local adhesions, or peritonitis. Most patients develop sealed-off abscesses or contained sinus tracts and fistulas. Fistulas usually involve adjacent structures, such as the bowel, urinary bladder, vagina, and anterior abdominal wall. Other potential complications include bowel obstruction and peritonitis.7
Diverticular disease is the most common colon disease in Western nations. In the West, colonic diverticula occur in 5% of the population by the time individuals are aged 40 years. They affect 33-50% of the population older than 50 years and more than 50% of the population older than 80 years.
Diverticulitis is the most common complication of diverticulosis, and it has been reported in 10-20% of patients with diverticulosis. The incidence of diverticulitis increases if the diverticula are numerous, if they have been present for more than a decade, and if they are distributed throughout the colon.
In underdeveloped nations in Asia and Africa, diverticulosis occurs in less than 0.2% of the population. This low rate is probably the result of a high-fiber diet. In immigrants to Western nations from Asia and Africa, the frequency of diverticulitis increases within 10 years.
Approximately 20% of patients with diverticulitis require surgical treatment. In a study by Belmonte et al, patients with diverticulitis with pelvic abscesses or generalized peritonitis had a mortality rate of 7.7%.8 Of patients treated for diverticulitis, 5% experience a second occurrence within 2 years of the initial episode.
The incidence of diverticulosis and diverticulitis is related primarily to diet rather than race. However, right-sided diverticula, which are usually congenital, occur most commonly in Asians.
The incidences of both diverticulosis and diverticulitis are similar in males and females.
The incidence of diverticulosis and diverticulitis increases with age, and it is particularly common in patients older than 50 years.
Diverticula involve the sigmoid colon in as many as 95% of patients with diverticulosis. The cecum is involved in 5% of patients. The sigmoid is the narrowest portion of the colon, and it generates the highest intrasegmental pressures. The combination of numerous haustra and dehydrated stool in the sigmoid colon leads to segmentation, in which the sigmoid colon functions as multiple small compartments. These features account for the high incidence of diverticulosis in the sigmoid colon.
In Japan, right-sided diverticulosis is 5 times more common than left-sided diverticulosis. Sigmoid diverticula are usually acquired false diverticula and multiple. Right-sided diverticula are usually congenital and solitary.
Typical features of sigmoid diverticulitis include fever, leukocytosis, and left lower quadrant pain. Other clinical features include nausea, vomiting, flatulence, palpable masses, muscle guarding, and partial obstruction. Patients with diverticulitis also may have elevated C-reactive protein (CRP) levels and erythrocyte sedimentation rates (ESRs). Mild bleeding occurs in as many as 25% of patients.
Diverticulitis is clinically more severe in younger patients, particularly in patients younger than 40 years. Complications of diverticulitis include pericolic abscess and fistulas within the small bowel, vagina, urinary bladder, and abdominal wall.9
The preferred examination is CT scanning of the abdomen and pelvis. CT findings can help in confirming clinical suspicion of diverticulitis and in excluding other abdominal or pelvic disease. CT can help in evaluating and in staging inflammatory disease. CT can also be used to accurately plan a percutaneous intervention.
Ultrasonography is occasionally useful in diagnosing acute diverticulitis. Ultrasonography is inexpensive, noninvasive, and readily available. Sonography could be used if CT is not available.
Traditionally, barium enema imaging has been the primary method of examining patients in whom diverticulitis is suspected. Barium studies superbly depict diverticula, the colonic mucosa and lumen, spasm, and muscle hypertrophy.10
The major limitation of CT scanning is the potential difficulty in differentiating diverticulitis from colon carcinoma. Other limitations of CT are the high cost of the examination and its limited availability in certain regions of the world.
Ultrasonography might not be helpful in excluding diverticulosis or diverticulitis because of interference due to bowel gas.
Ulcerative Colitis
Epiploic appendagitis
Plain radiography
Plain radiographs usually do not show any findings in uncomplicated diverticulitis, but a left-sided pelvic mass, localized ileus, or partial bowel obstruction may be seen occasionally. Pneumoperitoneum, portal venous gas, and extraluminal air-fluid levels may be noted in patients with complicated diverticulitis.
Barium study
Prior to the advent of abdominal CT scanning, barium enema evaluation was the examination of choice for the diagnosis of diverticulitis. A single-contrast examination is the preferred method in patients in whom diverticulitis is suspected.
The appearance of diverticula varies with the projection in which they are viewed and with the amount of air and barium they contain. In profile, a diverticulum appears as a protrusion outside of the colon that is joined to the colonic wall by a neck. En face, a diverticulum may appear as a well-defined collection of barium or as a ring shadow. It may resemble a bowler hat.
On barium enema examination, diverticulitis can be diagnosed by recognizing a perforated diverticulum. Barium may track through a perforated diverticulum into a sinus tract, fistula, or abscess. Less commonly, it may extravasate freely into the peritoneum. A diverticular abscess may cause extrinsic compression of the colonic lumen. Initially, this compression occurs on the mesenteric side of the colon, but it may spread to encircle the lumen.
Many other features of diverticulitis are depicted on barium enema images. Narrowing, deformity, or displacement of the bowel lumen is commonly seen. The colon may have an abnormal mucosal pattern. A soft-tissue mass may be seen, and this mass may contain gas or air-fluid levels. Extraluminal tracts filled with barium may end blindly as sinus tracts or may connect with an adjacent organ as a fistula, most commonly to the bladder or bowel. Fistulas also may involve the vagina, ureter, hip, and soft tissues of the thigh. Occasionally, plain radiographs demonstrate colovesical fistulas with the presence of air in the bladder. Additional manifestations of diverticulitis include localized ileus and intestinal obstruction.
Fistula formation to the anterior abdominal wall can be evaluated by using a fistulogram.
Stefansson et al reported a sensitivity of 82% and a specificity of 81% in using barium enema in a group of 88 patients in whom diverticulitis was suspected.10
The primary disadvantage of barium enema examination in the evaluation of diverticulitis is its limited ability in cases of extraluminal disease. Abscesses that do not communicate with the colon may not be detected. Although communication with the urinary bladder may be demonstrated, only 20% of colovesical fistulas are revealed on barium enema evaluation. Alternative conditions, such as appendicitis, epiploic appendagitis, gynecologic pathology, and renal colic, may not be depicted.
Although barium enema evaluation is excellent for differentiating diverticulitis from colon carcinoma, this differentiation is occasionally difficult. In diverticulitis, the diverticula usually are seen along with a gradual zone of transition and preservation of the mucosal folds. In carcinoma, a much sharper zone of transition is seen, with destruction of the mucosal folds. However, because diverticulosis is common, diverticula often are seen in patients with colon carcinoma. If the lesion completely obstructs the passage of contrast material during the barium enema test, the differentiation of diverticulitis from carcinoma is usually not possible.
Techniques for the CT evaluation of diverticulitis vary from institution to institution. At the authors' institution, oral contrast material is administered to opacify the small bowel. The oral contrast agent usually does not reach the sigmoid colon, but colonic opacification usually is not necessary for the evaluation of diverticulitis.11 Occasionally, the rectal administration of contrast material may help in difficult cases.
CT with rectal contrast enhancement or CT cystography may help in diagnosing fistulas. At the authors' institution, the intravenous contrast material is administered routinely, although it usually is not essential for diagnosis. Intravenous contrast material may help in revealing diverticular abscesses and fistulas and in demonstrating the enhancement pattern of the colonic wall. However, it is probably more helpful in the diagnosis of alternative diseases that may mimic diverticulitis.12
Cho demonstrated that CT has a sensitivity of 93% for the diagnosis of diverticulitis, which is higher than the 80% sensitivity of barium enema studies.15 Often, CT is the only radiologic test needed to establish the diagnosis and to direct medical or surgical therapy or radiologic intervention.
False-negative CT scans result from the difficulty in detecting early-stage diverticulitis with only minor changes in the pericolic fat.
Increased attenuation in the pericolic fat is not specific for diverticulitis, and false-positive findings occur. The differential diagnosis includes neoplasm, inflammatory bowel disease, appendicitis, and epiploic appendagitis. The presence of fluid in the root of the mesentery and the engorgement of adjacent sigmoid mesenteric vasculature suggest an inflammatory process, and the absence of stranding of the pericolic fat is typical of carcinoma.
Eccentric colonic wall thickening or marked concentric wall thickening is suggestive of colon carcinoma. The wall in carcinoma is frequently thicker than 2 cm, whereas it is usually thinner than 1 cm in cases of diverticulitis. Although most cases of diverticulitis involve a segment of less than 10 cm, involvement of a segment greater than 10 cm is specific for diverticulitis. As with barium enema results, findings of overhanging edges or shoulder formation with a rigid lumen are typical of a carcinoma.
The presence of pericolic lymph nodes also suggests colon cancer rather than diverticulitis.16 In addition, a layered pattern of enhancement of the colonic wall is typical of an inflammatory process, such as diverticulitis, and it is not usually seen in carcinomas. However, in some patients, distinguishing diverticulitis from colon cancer by using CT alone may not be possible, and follow-up examination after resolution of the acute episode may be necessary. Biopsy may also be required.
The presence of diverticula in the involved segment is helpful in distinguishing diverticulitis from other inflammatory conditions of the colon. Epiploic appendagitis may result from torsion of an epiploic appendage or thrombosis of an appendageal vein, and patients present with localized abdominal pain with a sudden onset. CT scans typically demonstrate an ovoid fat-attenuation mass with surrounding stranding. The colonic wall usually is not thickened. These findings help differentiate epiploic appendagitis from diverticulitis.
Ultrasonography in patients with diverticulitis is performed transabdominally with a 2- to 4-MHz convex-array transducer and compression.17,18,19
In diverticulitis, ultrasonographic findings include thickening of the bowel wall by more than 4 mm. Inflamed diverticula appear as round or ovoid highly echogenic structures with a ring-down artifact. Inflammation of the pericolic fat is revealed as an area of increased echogenicity adjacent to the colonic wall. Abscess formation appears as a well-defined hypoechoic mass near the colon, and it may demonstrate shadowing because of the presence of air. The absence of peristalsis is helpful for differentiating abscess from adjacent loops of bowel. Intramural sinus tracts appear as linear echogenic foci, often with ring-down artifacts. In addition, the patient may experience pain with compression of the affected region.
According to Pradel et al, the sensitivity of sonography is 85%, and its specificity is 84% in the diagnosis of diverticulitis.20 These are similar to the results of CT. However, ultrasonography is operator dependent, and technologists at most centers in the United States have little experience with its use in the evaluation of diverticulitis. Sonography may be totally unsuccessful, and sonograms may not show the colon in obese patients or in those with bowel gas.
False-positive findings result from the presence of neoplasms, inflammatory or ischemic colonic diseases, or adjacent extracolonic inflammatory conditions.
Scanning with technetium 99m – labeled red blood cells often is performed to locate the site of active gastrointestinal tract bleeding, and it may be helpful in evaluating the bleeding due to diverticulosis. Nuclear medicine studies have a limited role in the evaluation of diverticulitis.
Approximately one half of all cases of lower gastrointestinal hemorrhage are caused by colonic diverticulosis. Although most diverticula occur in the left side of the colon, diverticular hemorrhage usually originates from the right side. Angiography may demonstrate diverticular hemorrhage as puddling or staining that persists beyond the capillary and venous phases. Embolization or the intra-arterial infusion of vasopressin may be used to treat gastrointestinal bleeding.
Treatment in patients with acute diverticulitis varies with the severity and type of the disease.21,22 Antibiotic therapy may be adequate for treating mild cases of diverticulitis. Percutaneous drainage with CT or ultrasonographic guidance may be used in patients with large diverticular abscesses. Approximately 20% of patients with diverticulitis require surgical treatment.8 Surgery may be necessary to treat abscesses; fistulas; free perforations; bowel obstructions; and, occasionally, hemorrhage.23
Balthazar EJ. Diverticular disease. In: Textbook of Gastrointestinal Radiology. WB Saunders Co;1994: 1072-97.
Tonelli F, Di Carlo V, Liscia G, Serventi A. [Diverticular disease of the colon: diagnosis and treatment. Consensus Conference, 5th National Congress of the Italian Society of Academic Surgeons]. Ann Ital Chir. Jan-Feb 2009;80(1):3-8. [Medline].
Sarma D, Longo WE. Diagnostic imaging for diverticulitis. J Clin Gastroenterol. Nov-Dec 2008;42(10):1139-41. [Medline].
Sheiman L, Levine MS, Levin AA, Hogan J, Rubesin SE, Furth EE, et al. Chronic diverticulitis: clinical, radiographic, and pathologic findings. AJR Am J Roentgenol. Aug 2008;191(2):522-8. [Medline].
Panghaal VS, Chernyak V, Patlas M, Rozenblit AM. CT features of adnexal involvement in patients with diverticulitis. AJR Am J Roentgenol. Apr 2009;192(4):963-6. [Medline].
Beuran M, Iordache F, Chiotoroiu AL, Teleanu G, Vartic M, Turculet C, et al. Complicated diverticular disease--our recent experience. Chirurgia (Bucur). Jan-Feb 2009;104(1):25-9. [Medline].
Heise CP. Epidemiology and Pathogenesis of Diverticular Disease. J Gastrointest Surg. Feb 16 2008;[Medline].
Belmonte C, Klas JV, Perez JJ, et al. The Hartmann procedure. First choice or last resort in diverticular disease?. Arch Surg. Jun 1996;131(6):612-5; discussion 616-7. [Medline].
Tursi A, Brandimarte G, Giorgetti G, Elisei W, Maiorano M, Aiello F. The Clinical Picture of Uncomplicated Versus Complicated Diverticulitis of the Colon. Dig Dis Sci. Jan 30 2008;[Medline].
Stefansson T, Nyman R, Nilsson S, et al. Diverticulitis of the sigmoid colon. A comparison of CT, colonic enema and laparoscopy. Acta Radiol. Mar 1997;38(2):313-9. [Medline].
Rao PM, Rhea JT, Novelline RA, et al. Helical CT with only colonic contrast material for diagnosing diverticulitis: prospective evaluation of 150 patients. AJR Am J Roentgenol. Jun 1998;170(6):1445-9. [Medline].
Jang HJ, Lim HK, Lee SJ, et al. Acute diverticulitis of the cecum and ascending colon: the value of thin-section helical CT findings in excluding colonic carcinoma. AJR Am J Roentgenol. May 2000;174(5):1397-402. [Medline].
Horton KM, Corl FM, Fishman EK. CT evaluation of the colon: inflammatory disease. Radiographics. Mar-Apr 2000;20(2):399-418. [Medline].
Rao PM, Rhea JT. Colonic diverticulitis: evaluation of the arrowhead sign and the inflamed diverticulum for CT diagnosis. Radiology. Dec 1998;209(3):775-9. [Medline].
Cho KC, Morehouse HT, Alterman DD, Thornhill BA. Sigmoid diverticulitis: diagnostic role of CT--comparison with barium enema studies. Radiology. Jul 1990;176(1):111-5. [Medline].
Chintapalli KN, Chopra S, Ghiatas AA, et al. Diverticulitis versus colon cancer: differentiation with helical CT findings. Radiology. Feb 1999;210(2):429-35. [Medline].
Hollerweger A, Rettenbacher T, Macheiner P, et al. Sigmoid diverticulitis: value of transrectal sonography in addition to transabdominal sonography. AJR Am J Roentgenol. Oct 2000;175(4):1155-60. [Medline].
Kori T, Nemoto M, Maeda M, et al. Sonographic features of acute colonic diverticulitis: the "dome sign". J Clin Ultrasound. Sep 2000;28(7):340-6. [Medline].
Oudenhoven LF, Koumans RK, Puylaert JB. Right colonic diverticulitis: US and CT findings--new insights about frequency and natural history. Radiology. Sep 1998;208(3):611-8. [Medline].
Pradel JA, Adell JF, Taourel P, et al. Acute colonic diverticulitis: prospective comparative evaluation with US and CT. Radiology. Nov 1997;205(2):503-12. [Medline].
Hussain A, Mahmood H, Subhas G, El-Hasani S. Complicated diverticular disease of the colon, do we need to change the classical approach, a retrospective study of 110 patients in southeast England. World J Emerg Surg. 2008;3:5. [Medline].
Peppas G, Bliziotis IA, Oikonomaki D, Falagas ME. Outcomes after medical and surgical treatment of diverticulitis: a systematic review of the available evidence. J Gastroenterol Hepatol. Sep 2007;22(9):1360-8. [Medline].
Kassab A, El-Bialy G, Hashesh H, Callen P. Magnetic resonance imaging and hysteroscopy to diagnose colo-uterine fistula: A rare complication of diverticulitis. J Obstet Gynaecol Res. Feb 2008;34(1):117-20. [Medline].
diverticulitis, diverticulum, diverticulosis, diverticular disease, diverticular disease of the colon, outpouching, diverticula, colonic diverticula, intestinal disease, diverticular hemorrhage, bowel obstruction, gastrointestinal hemorrhage, GI tract hemorrhage
Sandor Joffe, MD, Section Chief of Abdominal Imaging, Department of Radiology, Beth Israel Medical Center
Sandor Joffe, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, and Radiological Society of North America
Disclosure: Nothing to disclose.
Aspasia Kachulis, MD, Body Imaging Fellow, Department of Radiology, Beth Israel Medical Center
Aspasia Kachulis, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, and Radiological Society of North America
Disclosure: Nothing to disclose.
John L Haddad, MD, Clinical Associate Professor, Department of Radiology, Weill Medical College of Cornell University; Director of Body MRI, Department of Radiology, Methodist Hospital in Houston
John L Haddad, MD is a member of the following medical societies: American College of Radiology, American Medical Association, and Radiological Society of North America
Disclosure: Nothing to disclose.
Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.
Spencer B Gay, MD, Professor of Radiology, Director of Body Computed Tomography, Department of Radiology, University of Virginia Health Sciences Center
Disclosure: Nothing to disclose.
Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.
Eugene C Lin, MD, Consulting Radiologist, Virginia Mason Medical Center; Clinical Assistant Professor of Radiology, University of Washington School of Medicine
Eugene C Lin, MD is a member of the following medical societies: American College of Nuclear Medicine, American College of Radiology, Radiological Society of North America, and Society of Nuclear Medicine
Disclosure: Nothing to disclose.
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