High-Resolution Sonographic Spectrum of Diverticulosis, Diverticulitis, and Their Complications

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1 Image Presentation High-Resolution Sonographic Spectrum of Diverticulosis, Diverticulitis, and Their Complications S. oopathy Vijayaraghavan, MD, DMRD Objective. The purpose of this study was to evaluate the high-resolution sonographic features of diverticulosis, diverticulitis, and their complications. Methods. During a period of about 4 years 8 months, there were 25 patients with sonographic features of diverticulosis, uncomplicated diverticulitis, and complicated diverticulitis. The clinical symptoms, sonographic features, follow-up investigations, and management details were recorded. Results. The common symptoms were pain in the left lower quadrant and fever. Sonographic features of uncomplicated diverticulitis were a varying appearance of the diverticulum with pericolic inflammation. Colonic wall thickening was not a consistent sign. Complications seen were pericolic, mesocolic, and intraperitoneal abscesses, colovesical fistulas, colouterine fistulas, perforation, and small-bowel obstruction. Uninflamed diverticula were seen in all patients with left-sided disease. They had 7 types of sonographic appearances. Conclusions. Uncomplicated diverticulitis is seen as a diverticulum of variable echogenicity with pericolic inflammation. n inflamed diverticulum is not visualized in complicated diverticulitis. Visualization of uninflamed diverticula helps reinforce the diagnosis of uncomplicated diverticulitis and predict the cause in complicated diverticulitis. Key words: diverticulitis; diverticulosis; sonography. Received July 2, 2005, from Sonoscan Ultrasonic Scan Centre, Coimbatore, India. Revision requested ugust 24, Revised manuscript accepted for publication September 8, ddress correspondence to S. oopathy Vijayaraghavan, MD, DMRD, 16 Venkatachalam Rd, R. S. Puram, Coimbatore , India. sonoscan@vsnl.com or sboopathy@eth.net Video online at Diverticulosis of the colon is characterized by numerous saccular outpouchings in the colon. Most of them are actually acquired pseudodiverticula, consisting of herniations of the mucosa and submucosa through the muscular coat of the colon. Some of them are true diverticula containing all layers of the bowel wall, and these are congenital. The anatomic distribution of the diverticula also varies with the geographic location. Left-sided colonic diverticula are common in Western countries, less common in South merica, and rare in frica and sia. 1 Right-sided diverticulosis is much more common in sia. 2 It is uncommon before the age of 40 years and increases in frequency with age. Diverticulitis is inflammation of a diverticulum. It can be uncomplicated, or it can result in complications such as perforation. In this presentation, the high-resolution sonographic features of diverticulosis, diverticulitis, and their various complications are illustrated by the merican Institute of Ultrasound in Medicine J Ultrasound Med 2006; 25: /06/$3.50

2 High-Resolution Sonography of Diverticulosis and Diverticulitis Materials and Methods etween May 2000 and December 2004, there were 25 patients with sonographic features suggestive of diverticulosis, uncomplicated diverticulitis, or complicated diverticulitis. The clinical features of the patients were recorded. Sonography was performed initially with an HDI 3500 scanner and later with HDI 4000 and HDI 5000 Scanners (Philips Medical Systems, othell, W), using convex 2- to 5-MHz, convex 4- to 7-MHz, and linear 5- to 12-MHz probes. Sonography was performed with a graded compression technique. 3 Final diagnosis was based on a barium enema study (16 patients), computed tomographic scanning (2 patients), cystoscopy (3 patients), laparotomy (8 patients), or a combination thereof. Results Of the 25 patients, 17 (68%) were male and 8 (32%) were female. The age of the patients ranged from 31 to 95 years for left-sided disease and 24 to 62 years for right-sided disease. Pain in the left lower quadrant was the most common symptom (Table 1). Three patients were referred for problems unrelated to diverticulosis. Two of them were previously known to have diverticulosis. One patient who had acute pancreatitis was found to have diverticulosis of the sigmoid colon on sonography. In 7 patients, the symptoms were related to the complications of diverticulitis. The sonographic findings are summarized in Table 2. Uncomplicated diverticulitis was seen in 11 patients. Pericolic inflammation was seen in all of them. It was seen as echogenic fat with loss of compressibility. Colonic wall thickening (>5 mm) was seen in 7 of them. mong these 11 patients, Table 1. Symptoms of Patients With Diverticulitis Symptom Left-sided disease 20 Pain in left lower quadrant 14 Fever 4 cute abdomen 3 Loose stools 2 Pneumaturia 2 Urinary tract infection 1 Foul-smelling vaginal discharge 1 Right-sided disease 2 Pain in right lower quadrant 2 Total 22 n multiple diverticula were seen in thick-walled segments of the colon in 2 (Figure 1). In the remaining 9 patients, only 1 inflamed diverticulum was seen. It was seen as a hypoechoic diverticulum (Figure 2), an echogenic diverticulum with a hypoechoic peripheral zone (Figure 2), or an echogenic diverticulum with acoustic shadowing (fecalith) and a hypoechoic peripheral zone (Figure 2C). Of these, 2 were diverticulitis of the cecum (Figure 3), and the rest were leftsided. pericolic abscess with pericolic inflammation was seen in 4 patients (Figure 4). One of them had an additional abscess in the thickened and echogenic sigmoid mesocolon (Figure 5). Other complications of diverticulitis were seen in 7 patients, the descriptions of which are given below. Case 1 46-year-old man had an acute abdomen. There was pneumoperitoneum seen to the left of the umbilicus with a hypoechoic tract extending from this region to a normal-appearing sigmoid colon (Figure 6). There were a few uninflamed diverticula in the proximal colon. Laparotomy revealed diverticulitis of the sigmoid colon with perforation, and resection of the sigmoid colon was performed. Cases 2 and 3 Two men aged 53 and 59 years had pneumaturia. One of them also had a history of recurrent urinary tract infections. Sonography revealed air in the urinary bladder (Figure 7) and a fistulous tract between the urinary bladder and the sigmoid colon (Figure 8). water enema showed a Table 2. Sonographic Findings of Patients With Diverticulitis Finding Uncomplicated diverticulitis 11 Left colon 9 Cecum 2 Complicated diverticulitis 11 Pericolic and mesocolic abscess 4 Perforation 1 Colovesical fistula 2 Mass, colovesical fistula 1 Small-bowel obstruction 1 Colouterine fistula 1 Intraperitoneal abscess with 1 small-bowel obstruction Uninflamed diverticula 20 Total patients 22 n 76 J Ultrasound Med 2006; 25:75 85

3 Vijayaraghavan gush of fluid from the colon into the urinary bladder (Figure 9 and Video 1). There were multiple uninflamed diverticula in the proximal sigmoid colon. The diverticulosis was confirmed by a barium enema study. The colovesical fistula was seen on the barium enema study and cystoscopy. The patients underwent surgery, in which resection of the fistula and sigmoid colon was done. Case 4 45-year old man had pain in the left lower quadrant. Sonography revealed a hypoechoic mass close to the dome of the urinary bladder with inflamed fat around it (Figure 10). It mimicked a urachal mass, but there were uninflamed diverticula of the sigmoid colon, indicating that the mass could be due to an inflamed diverticulum. The patient s condition was managed conservatively. rescan done 10 days later showed marked resolution of the mass. There was air in the urinary bladder. water enema revealed a colovesical fistula, which was confirmed by cystoscopy and a barium enema. It was later corrected by surgery. Figure 2. Scans of the sigmoid colon (SI) showing uncomplicated diverticulitis with pericolic inflammation (arrowheads). The diverticulum (arrows) appears hypoechoic (), echogenic with a hypoechoic peripheral zone (), and echogenic with dense shadowing (fecalith) and a hypoechoic peripheral zone (C). Case 5 75-year-old woman was referred for sonography for pain in the abdomen and vomiting. Sonography revealed small-bowel obstruction. There was a tender mass of thick-walled small bowel and thick-walled sigmoid colon (Figure Figure 1. Oblique scan of the left iliac fossa showing the thickwalled sigmoid colon with multiple echogenic diverticula (arrows) and inflamed pericolic fat. C J Ultrasound Med 2006; 25:

4 High-Resolution Sonography of Diverticulosis and Diverticulitis showed air in the uterine cavity (Figure 12). There was an air-filled tract extending from the uterine cavity into a thick-walled sigmoid colon (Figure 12). There were multiple uninflamed diverticula in the proximal sigmoid colon. Laparotomy revealed a mass involving the sigmoid colon and the fundus of the uterus with diverticulosis of the sigmoid colon, which was removed. Histopathologic examination confirmed diverticulitis of the sigmoid colon with a colouterine fistula. Figure 3. Scan of the right iliac fossa showing uncomplicated diverticulitis of the cecum. The arrow points to an echogenic diverticulum with inflamed fat around it (arrowheads). CE indicates cecum. 11). There were multiple inflamed diverticula in this segment of the sigmoid colon (Figure 11) and uninflamed diverticula in the proximal colon. The patient s condition was managed conservatively. Later, diverticulosis was confirmed by a barium enema study, and resection of the sigmoid colon was done. Case 6 70-year-old postmenopausal woman had a foul-smelling vaginal discharge. Sonography Case 7 59-year-old man had acute pain in the abdomen and vomiting. Sonography revealed small-bowel obstruction due to an intraperitoneal abscess containing some air (Figure 13). The abscess was located in the left lumbar region, medial to the descending colon. There were multiple diverticula in the distal descending colon and the sigmoid colon. Laparotomy revealed small-bowel obstruction due to an intraperitoneal pericolic abscess caused by complicated diverticulitis of the descending colon. There was diverticulosis of the descending and sigmoid colon. Resection of the diseased segment of the colon was done. Uninflamed diverticula were seen in the colon away from the diseased segment in all the patients with left-sided disease. They were seen in 9 patients with uncomplicated diverticulitis of the left colon, 4 with a pericolic abscess, and 7 with complicated diverticulitis. They were also Figure 4. Scans of the left iliac fossa showing a pericolic abscess () with surrounding inflamed fat. The abscess is filled with fluid in and fluid and air in. L indicates urinary bladder; and SI, sigmoid colon. 78 J Ultrasound Med 2006; 25:75 85

5 Vijayaraghavan Figure 5. Oblique scan of the left iliac fossa showing an abscess (arrowhead) in the thick and echogenic sigmoid mesocolon (arrows) away from the sigmoid colon (SI). seen in 3 patients with diverticulosis who had sonography for unrelated clinical conditions. The number of such diverticula varied from 1 to 5 in each patient. They showed 7 types of appearance on sonography (Table 3). The first 3 types were seen as outpouchings from the colon because of a visible hypoechoic wall of the diverticulum with varying appearance of the center, when compared with the normal contour of the colon (Figure 14). The appearance of the center of the diverticulum was (1) hypoechoic when there was no air in it (Figure 14), (2) echogenic when there was a varying amount of air (Figure 14, C and D), and (3) echogenic with a dense shadow because of fecalith (Figure 14E). The next 3 types of appearance were seen as (4) oval or round echogenic masses (Figure 15), (5) echogenic masses with a dense shadow due to fecalith (Figure 15), and (6) an echogenic line (Figure 15C) outside the contour of the colon. The wall of the diverticulum was not visible in these 3 types. The seventh type of appearance was an intramural echogenic line contiguous with the echogenic lumen of the colon (Figure 16). More than 1 type of appearance was seen in the same patient. The numbers of patients in whom the various types of appearance were seen were as follows: type 1 in 3 patients, type 2 in 12, type 3 in 7, type 4 in 18, type 5 in 4, type 6 in 3, and type 7 in 3 (Table 3). Discussion Diverticulitis of the colon results from inflammation of a colonic diverticulum. The initial event is a microperforation of the wall of the diverticulum, which results in peridiverticulitis or phlegmon and is referred to as uncomplicated diverticulitis. Complicated diverticulitis ensues if continuation of the inflammatory and septic process is associated with an abscess, obstruction, free perforation, or a fistula. The most common symptoms include left lower quadrant abdominal pain (93% 100%), fever (57% 100%), and leukocytosis (69% 83%). 1 If there has been progression of the disease process, the patient may report symptoms of complicated diverticulitis such as recurrent urinary tract infections, pneumaturia that results from a colovesical fistula, or a feculent vaginal discharge from a colouterine fistula. The patient with free perfora- Figure 6. Longitudinal scan in the left lower abdomen showing free peritoneal air (arrows) with a hypoechoic tract (arrowhead) up to a normal-looking sigmoid colon (SI). Figure 7. Longitudinal scan of the urinary bladder (L) showing air (arrow) in it. J Ultrasound Med 2006; 25:

6 High-Resolution Sonography of Diverticulosis and Diverticulitis Figure 8. Oblique scan through the urinary bladder and left iliac fossa showing an air-filled tract (arrow) extending from the sigmoid colon (SI) into the lumen of the urinary bladder (L). tion and peritonitis has acute peritoneal signs and abdominal wall rigidity consistent with a perforated viscus. Diverticula develop in rows between the mesenteric and the 2 lateral taeniae. They may be intraperitoneal or extraperitoneal in location. The complications of diverticulitis depend on the location of the diverticulum and its neighboring organs. Extraperitoneal diverticulitis can develop into a pericolic abscess. Intraperitoneal diverticulitis can result in perforation into the peritoneal cavity, an intraperitoneal abscess, or fistula formation with the urinary bladder, the small bowel, or, rarely, the uterus. Sonography and computed tomography are the imaging methods of choice for the diagnosis of acute colonic diverticulitis, with similar performance of 94%. 4 7 ecause sonography is operator dependent, proper technique and direct physician involvement in the examination may be crucial for making an accurate diagnosis. The sonographic examination using graded compression is well tolerated by patients and should be used to localize the painful area. The same technique is used to study the colon, proximal or distal to the diseased segment, to look for the uninflamed diverticula. Colonic mural thickening, pericolic inflammation, and, at times, the visualization of diverticula are the most common criteria used for the sonographic diagnosis of diverticulitis Hollerweger et al 7 assessed the value of visualization of an inflamed diverticulum as a sign of diverticulitis. Even though they considered segmental bowel wall thickening ( 5 mm), pericolic inflammation (altered echogenicity of pericolic fat and loss of compressibility), inflamed diverticula, and evidence of complicated disease (perforations, abscesses, and fistulas) as indications of diverticulitis, nonvisualization of inflamed diverticula or complications was taken as a negative finding for diverticulitis. They described 4 types of sonographic appearance of an inflamed diverticulum. They were hypoechoic, predominantly echogenic, an echogenic center with a surrounding hypoechoic rim, and an echogenic mass with acoustic shadowing and, usually, a peripherally hypoechoic rim. They were able to diagnose 94% of cases of diverticulitis using these criteria. n inflamed diverticulum as a sonographic sign of diverticulitis had overall sen- Figure 9. Image after a water enema showing the echogenic gush of fluid (arrow) from the colon into the urinary bladder (L). Figure 10. Longitudinal scan of the urinary bladder showing a hypoechoic mass (M) close to the dome of the urinary bladder (L) with inflamed fat around it. 80 J Ultrasound Med 2006; 25:75 85

7 Vijayaraghavan Figure 11., Scan of the left lower quadrant showing a large mass of thick-walled small bowel (S) and the sigmoid colon (SI) with inflamed fat around it., Scan slightly below the section in showing a thick-walled sigmoid colon (SI) with inflamed thick-walled diverticula (arrows). sitivity of 77%. pplying this sign only to patients with uncomplicated diverticulitis, sensitivity improved from 77% to 96%. This result was due to the fact that, in the cases of complicated diverticulitis, the diverticula are involved in the inflammatory process and are dissolved by phlegmonous inflammation and gangrene. Hence they are not seen. In the series presented here, 1 of the patterns of an inflamed diverticulum described by Hollerweger et al, 7 along with pericolic inflammation, was seen in all 11 patients with uncomplicated diverticulitis. Colonic wall thickening was seen in only 7 of these 11 patients, but uninflamed diverticula were seen away from the involved segment of the colon in all patients, reinforcing the diagnosis of diverticulitis. In patients with complicated diverticulitis, the symptoms and clinical features were not related to diverticulitis and were those of the complications. 13 In the series presented here, there were 11 cases of complicated diverticulitis: 4 pericolic abscesses, 1 perforation, 3 colovesical fistulas, 1 colouterine fistula, 1 intraperitoneal abscess with small-bowel obstruction, and 1 small bowel obstruction. In all these patients, uninflamed Figure 12., Longitudinal scan of the pelvis in a postmenopausal woman showing air in the uterine cavity and a thick-walled sigmoid colon. L indicates urinary bladder; SI, sigmoid colon; and UT, uterus., Oblique scan of the pelvis and left iliac fossa showing an air-filled tract (arrow) extending from the uterine cavity into the adjacent thick-walled sigmoid colon. J Ultrasound Med 2006; 25:

8 High-Resolution Sonography of Diverticulosis and Diverticulitis Figure 13. Transverse scan of the left middle quadrant showing an intraperitoneal abscess (arrow) with some air (arrowhead) medial to the descending colon (C). Table 3. Sonographic ppearance of Uninflamed Diverticula ppearance With visible wall Outpouching with hypoechoic center 3 Outpouching with echogenic center 12 due to air Outpouching with a densely shadowing 7 fecalith Without visible wall Oval or round echogenic mass outside 18 the colon Echogenic mass with dense shadow 4 (fecalith) outside the colon Echogenic line outside the colon 3 Other Intramural echogenic line 3 n diverticula were seen away from the diseased segment. The visualization of uninflamed diverticula is useful for reinforcing the diagnosis of uncomplicated diverticulitis. In complicated diverticulitis, the visualization of an uninflamed diverticulum is a clue for the cause of the complication, and in this series, this finding helped in predicting diverticulitis as the cause in 7 cases of complicated diverticulitis, which were confirmed by surgery. To my knowledge, the article by Hollerweger et al 7 is the only study of uninflamed diverticula. They studied the uninflamed diverticula in control subjects and described the appearance of all the uninflamed diverticula as rounded or oval echogenic outpouchings of the colonic wall, with or without a thin peripheral hypoechoic rim of less than 1 mm. The pericolic inflammation was absent. In the series presented here, uninflamed diverticula were seen in all the patients with uncomplicated and complicated diverticulitis of the left colon and in 3 control subjects, 2 known and 1 unknown to have diverticulosis. The uninflamed diverticula had 7 types of sonographic appearances: 3 types were seen as welldefined outpouchings with a visible wall and a varying appearance of the center. The center appeared hypoechoic without air or echogenic and filled with varying amounts of air or a densely shadowing fecalith. They were also seen as oval or round echogenic masses and a densely shadowing echogenic mass without a visible wall outside the contour of the colon. Some of them were seen just as echogenic lines in the pericolic space, representing the air in the diverticula, in which the wall of diverticulum was invisible. Rarely, they were seen as intramural echogenic lines, contiguous with the echogenic lumen. Diverticula with different appearances may be seen in the same patient. The association of diverticulosis and ulcerative colitis can mimic diverticulitis. In ulcerative colitis, the inflammation is over a longer segment of the colon, and the pericolic inflammation surrounds the colon, whereas it is focal in diverticulitis. Crohn disease and contained perforated colonic cancer are 2 other conditions that mimic diverticulosis with pericolic inflammation, fistulas, and abscess formation. In both these conditions, an inflamed diverticulum is not shown. Furthermore, uninflamed diverticula away from the diseased segment are also absent in these diseases. barium enema or colonoscopy is necessary, after resolution of the acute phase of the disease, to rule out these diseases. In conclusion, the sonographic appearance of uncomplicated diverticulitis is very characteristic. It shows a diverticulum of variable echogenicity with pericolic inflammation. Colonic wall thickening is not a consistent sign. n inflamed diverticulum is not visualized in complicated diverticulitis because it is dissolved in the process. Visualization of uninflamed diverticula away from the segment helps reinforce the diagnosis of uncomplicated diverticulitis and predict the cause of the complication in complicated diverticulitis. 82 J Ultrasound Med 2006; 25:75 85

9 Vijayaraghavan C D Figure 14. Images of the left lower quadrant showing a normal colon with pericolic fat () and uninflamed diverticula (arrows) seen as outpouchings with a visible hypoechoic wall and hypoechoic center (), an echogenic center with a bubble of air (C), an echogenic center with more air (D), and an echogenic center with dense shadowing due to fecalith (E). E J Ultrasound Med 2006; 25:

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