Downloaded from www.ajronline.org by 125.224.244.161 on 11/05/15 from IP address 125.224.244.161. Copyright ARRS. For personal use only; all rights reserved

283

Uncomplicated Acute Diverticulitis of the Cecum and Ascending Colon: Sonographic Findings in 18 Patients

Mitsuyoshi Yoichi

Wada1 Kikuchi1 Mikio Do?

To determine

the sonographic

features

of uncomplicated

acute

diverticulitis

of the

cecum and ascending colon, the sonographic findings in 534 patients who presented with right lower quadrant pain were reviewed. Of these, 18 patients had uncomplicated acute diverticulitis of the cecum and ascending colon. The diagnosis was confirmed by surgery (one patient), clinical course (17 patients), CT (eight patients), or contrast enema (1 1 patients). On sonography, a round or oval focus of varying echogenicity, which

protruded

from a segmentally

thickened

colonic

wall and was surrounded

by a hyper-

echoic area, was seen in all 18 patients. These were hypoechoic foci (12 patients), hypoechoic foci with internal strong echoes (three patients), and echogenic shadowing foci with surrounding hypoechoic bands (three patients). Extraluminal gas (one patient) and thickening of lateroconal fascia (six patients) were seen also. Findings of enlarged appendix, frank abscess, and ascites were absent. All patients, including the one who had laparotomy, were successfully treated medically for diverticulitis. Of 515 patients without diverticulitis, in only one patient with acute appendicitis did sonography show a hypoechoic protruding focus. Our experience indicates plicated acute diverticulitis

protruding AJR

from a segmentally

155:283-287,

August

that the major sonographic finding in patients with uncomof the right colon is a hypoechoic round or oval focus

thickened

colonic

wall.

1990

Acute diverticulitis of the cecum and ascending colon can cause right lower quadrant pain. Differentiation from acute appendicitis is important because acute diverticulitis of the colon without complications such as frank abscess, fistula, obstruction, and free perforation is treated medically [1 ]. Although contrast enema and CT have been used in the evaluation of acute diverticulitis of the right colon [2-5], few reports have been published on the usefulness of sonography in this condition [6-8]. We studied the sonograms of 1 8 patients with uncomplicated acute diverticulitis of the right colon to determine the sonographic features of the disease. The study is limited by the fact that the diagnosis was confirmed only by the patients’ clinical course (1 7 patients), CT findings (eight patients), or contrast enema studies (1 1 patients), except for one surgically proved case.

Materials 4, 1990; accepted

after

revi-

Ce;: aki 305, Wada. 2

Japan.

Department

Center

Hospital,

Address of

reprint

Pathology,

1 -3-1 Amakubo,

aki 305, Japan. 0361 -803X/90/1552-0283 Roentgen

0 American

requests Tsukuba Tsukuba-shi,

to

M.

Medical lbar-

January 1990,pain. sonognaphy waspatients performed at our diverticulitis hospital 534Between patients January with acute1 988 rightand lower quadrant Of these, 19 had acute of the right colon. was excluded from

One patient the analysis

had complicated of sonognaphic

diverticulitis findings. The

with an ileocecal 1 8 patients who

abscess

in

and

are the subject of this study had uncomplicated acute diverticulitis of the right colon confirmed by surgery (one patient), clinical course (1 7 patients), CT (eight patients), on contrast enema (1 1 patients). Follow-up imaging

Ray Society

and Methods

There presented

sonognaphy study were with

other

was than

the

performed initial

in six

patients.

Two

patients

did

not

undergo

any

sonography.

1 4 men and four women right lower quadrant pain

28-58 and

years old (mean, 39 years). All 18 patients

tenderness.

Nausea

on vomiting

was

present

in

284

WADA

five

patients.

physical

None

presentation history

Downloaded from www.ajronline.org by 125.224.244.161 on 11/05/15 from IP address 125.224.244.161. Copyright ARRS. For personal use only; all rights reserved

of these

examination and

15

sonographic night

colon

in

40

had

leukocytosis.

was unit

The

was

patient

a Hitachi

with

All CT

uncomplicated and

with

a 3.5-MHz unit

studies

with

patients acute

two

was

ureteral

convex

with

transducer

performed

on

initial of the recom-

tenderness,

and laparota Hitachi

EUB-

in 17 patients

convex

transducer

a Toshiba

a

stone

The was

and

with certainty

performed

had

diverticulitis

pain

at

appendi-

patients.

management

on

febnile

Five

patients,

abdominal

a 7.5-MHz

were

palpated

were

was

acute

medical

severe

Sonography

EUB-450

patient.

diagnosis

could not be excluded

performed. (Tokyo)

clinical

was

patients

or tumor in two in the other

abscess undetermined

acute appendicitis omy

patients

1 7 patients

In one

A mass

Sixteen

impression

mended.

diarrhea.

patient.

of appendectomy.

citis in 1 3 patients, in one patient, and

had

in one

and in one

TCT-70A

unit

(Tokyo). The

initial

and

CT, contrast uncomplicated two

acute

of the

ulitis

were

to

sonographic

Also,

who

had

diagnoses

if any

of the

in these

of the

all reports

see

present

findings

and clinical records diventiculitis

authors.

51 5 patients reviewed

subsequent

enema,

other sonographic

night

in

the

colon

of sonographic than

acute findings

and 18 were

findings

patients

on

with

reviewed studies

diverticulitis of acute

by in the were

divertic-

patients.

Results Sonographic colon in nine

abnormalities were seen in the ascending patients and in the cecum in nine patients. A

ET AL.

AJA:155,

August

1990

thickened colonic wall (Figs. 1 -4) 5-1 5 mm thick and 2-5 cm long was present in all 18 patients and a slightly thickened terminal ileum was seen in one patient. In all 1 8 patients, sonography showed a round or oval focus of varying echogenicity protruding from the colon in both the transverse and longitudinal planes (Figs. 1 -4). The maximum diameter of these foci was 1 0-22 mm (mean, 1 3 mm). They were hypoechoic in 1 2 patients (Figs. 1 A and 2A), hypoechoic with internal spotty strong echoes in three patients (Fig. 3B), and echogenic shadowing foci with a surrounding hypoechoic band in the other three patients (Fig. 4). These protruding foci were surrounded by hyperechoic areas of varying degrees in all 1 8 patients (Fig. 3B). In five cases of cecal diverticulitis and one case of diverticulitis in the ascending colon, thickened lateroconal fasciae were seen on sonography (Figs. 1A and 2A). In one patient, a strong echo suggesting extraluminal gas immediately behind the hypoechoic protruding focus was confirmed by CT (Fig. 3). There was no finding of enlarged appendix, enlarged mesenteric lymph nodes, frank abscess, or ascites. CT was performed immediately after sonography in eight patients. On CT scans, regional colonic wall thickening and poorly defined or linear soft-tissue densities in the adjacent pericolic fat were seen in all eight patients (Figs. 1 B, 1C, and 3D). Thickening of the lateroconal fascia, which also was

Fig. 1.-Cecal diverticulitis in a 41-year-old man. A, Initial transverse sonogram of right lower quadrant shows round hypoechoic focus (arrowhead) protruding from thickened cecal wall (open arrows). Thickened lateroconal fascia (solid arrows) also is seen. B, CT scan obtained immediately after sonography shows small area of slightiy increased density (open arrow) adjacent to thickened cecal wall (solid arrows). This small high density corresponds to hypoechoic focus on sonogram. Soft-tissue density of pericecal inflammatory

change is behind cecum. C, CT slice 3 cm cephalad to B shows marked cecal wall thickening and gas-filled diverticulum (arrow) protruding from cecum. Pericecal inflammatory change and thickened lateroconal fascia (arrowheads) also are seen. D, Follow-up sonogram

5 days after initial study shows decreases in cecal wall thickening (arrows) and size of protruding hypoechoic focus

(arrowhead),

days later.

which

finally

disappeared

7

Downloaded from www.ajronline.org by 125.224.244.161 on 11/05/15 from IP address 125.224.244.161. Copyright ARRS. For personal use only; all rights reserved

AJR:155,

August

1990

DIVERTICULITIS

OF

CECUM

AND

ASCENDING

COLON

285

Fig. 2.-Cecal diverticulitis in a 29-year-old man. A, Transverse sonogram shows hypoechoic focus (arrowhead) protruding from thickened cccal wall (open arrows). Thickened lateroconal fascia (solid arrows) also are shown. B, Double-contrast barium enema after subsidence of acute stage reveals cecal diverticulum (arrow) at location corresponding to that on initial sonogram.

Fig. 3.-CecaI diverticulitis in a 58-year-oldman. A, Transverse sonogram of cecum shows hypoechoic focus (arrowhead) protruding from 10cally thickened cecal wall (solid arrows). Strong echo (open arrow) is seen immediately behind hypoechoic protruding focus. B, Longitudinal sonogram shows round hypoechoic focus (open arrow) with internal spotty strong echo and surrounding hyperechoic area (solid arrows). C, Slightiy lateral longitudinal sonogram shows hypoechoic focus (open arrow) and adjacent strong echo (arrowhead) suggesting cxtraluminal gas. Note acoustic shadowing (solid arrows). D, CT scan obtained immediately after sonography shows collection of gas (arrow) behind cecum (arrowheads). Pooriy defined soft-tissue density is present around gas collection. Followup barium enema showed cecal diverticula.

C present on sonography, was demonstrated in four patients (Fig. 1 C). In one patient, Gastrografin enema was performed before CT; it showed minimal mass effect and a few diverticula on the medial wall of the ascending colon without extravasation of the contrast material. A barium enema was performed after subsidence of the acute stage in 1 0 patients. In eight patients, diverticula were shown at the location corresponding

D to that on the initial sonogram (Figs. 2 and 4). In one patient, residual mass effect at the corresponding location was shown with a few adjacent diverticula. In another patient, the barium enema did not show diverticulum or mass effect. In six patients, follow-up sonography was performed less than 12 days after the initial sonographic examination. This study showed decreases in the colonic wall thickening and

Downloaded from www.ajronline.org by 125.224.244.161 on 11/05/15 from IP address 125.224.244.161. Copyright ARRS. For personal use only; all rights reserved

286

WADA

ET AL.

AJR:155,

Fig. 4.-Diverticulitis of ascending colon in a 56-year-old man. A, Transverse sonogram of right lower quadrant shows echogenic focus with surrounding hypoechoic band (solid arrows), from slightiy thickened colonic wall (open arrows). B, Longitudinal sonogram shows round echogenic shadowing focus with surrounding hypoechoic band (arrows). C, Follow-up double-contrast barium enema shows large diverticulum (arrow) protruding medially from ascending colon valve. A few small diverticula also are seen in ascending colon.

the

size

of the

protruding

foci

of these foci finally disappeared. oic focus became an echogenic three

patients,

the

sonographic

in all six patients

(Fig.

which

August

is protruding

immediately

1990

medially

above ileocecal

1). Two

In one patient, the hypoechshadowing focus. In the other characteristics

of the

focus

did not change. All patients, including the one who had laparotomy and appendectomy, were successfully treated medically for acute diverticulitis. Of the 51 5 patients without diverticulitis, in only one did sonography show a protruding hypoechoic focus from a thickened colonic wall. This patient was one of the 115 patients during the period of this study who had surgically proved appendicitis. There was a perforation at the proximal portion of his appendix about 1 cm from its origin. Although the

proximal

enlarged

appendix

was

seen

as a round,

pro-

truding, hypoechoic focus mimicking acute diverticulitis (Fig. 5), a distal enlarged appendix and adjacent round hypoechoic area of abscess formation led to the correct diagnosis of complicated

acute

appendicitis.

Of the

51 5 patients

without

diverticulitis, colonic wall thickening of varying lengths and thicknesses was seen in the right colon in 36 patients with the following conditions: acute appendicitis (1 6 patients), infectious colitis (six patients), colonic carcinoma (two patients), mesenteric adenitis and acute terminal ileitis (two patients), intussusception (two patients), Crohn disease (one patient), ischemic colitis (one patient), and undetermined (six patients).

Discussion Acute disease uncommon

diverticulitis in patients in the

of the right colon is not an uncommon of oriental ancestry [9]. It is relatively Western

population

and

is difficult

to diag-

nose on radiologic or clinical examination [1 0, 1 1 ]. CT and contrast enema are often helpful, but sometimes misdiagnoses of acute appendicitis and perforated colonic cancer are made [4, 1 2]. Although the use of sonography for the

Fig. 5.-Perforated acute appendicitis in a 35-year-old man. Transverse sonogram of right lower quadrant. Hypoechoic focus (curved arrow) protruding from thickened cecal wall (arrowheads) mimics finding in acute diverticulitis; however, separate, large hypoechoic area of abscess (straight arrow) and distal tubular hypoechoic structure (not shown) sug-

gested acute appendicitis with

perforation

with abscess formation. At surgery, appendicitis portion was found.

at its proximal

diagnosis of diverticulitis ofthe right colon has been described in a few reports [6-8], it is not widely accepted. In our series of 1 8 patients, common sonographic findings of uncomplicated acute diverticulitis were the visualization of a round or oval focus of varying echogenicity protruding from the colonic wall with a surrounding hyperechoic area and segmental colonic wall thickening. Pathologically, diverticulitis consists mainly of a small, flaskshaped, acute abscess lying in the pericolic fat that contains many neutrophils and necrotic material [1 3, 1 4]. We assume that the hypoechoic focus protruding from the colon reflects this flask-shaped abscess, and the internal strong echo may represent debris or possibly gas. In our series, these protruding foci

were

seen

in all 1 8 patients

with

acute

diverticulitis

Downloaded from www.ajronline.org by 125.224.244.161 on 11/05/15 from IP address 125.224.244.161. Copyright ARRS. For personal use only; all rights reserved

AJR:155,

August

1990

DIVERTICULITIS

OF

CECUM

and in only one of 1 1 5 patients with appendicitis. This finding appears to be the most specific and meaningful of the various sonographic findings seen in acute diverticulitis of the right colon. Around the flask-shaped abscess, a few neutrophils, fibrin, and necrotic tissues are scattered [1 4]. Probably these changes are seen as a hyperechoic area around the small abscess of the diverticulitis. The finding of thickened lateroconal fascia seen in six patients is most likely a manifestation of inflammatory change in the fascial plane. The findings of a pericolic hyperechoic area and thickened fascia could be seen in other conditions with inflammatory change in the pericolic space. Perulekar [15] stated that long-segment hypoechoic thickening of the colonic wall is the most common finding in diverticulitis of the sigmoid colon. In our series, however, the colonic wall was not as thick, ranging from 2 to 5 cm vs 7 to 1 5 cm in Perulekar’s series. In the sigmoid colon, muscular hypertrophy of diverticular disease could contribute to the thickening of the colonic wall seen on sonography. In addition, this discrepancy could be explained by the difference in the severity of the disease between our series and that of Perulekar, in which about half of the patients had complicated diverticulitis. Thickening of the colonic wall can be seen in inflammatory, infectious, or ischemic colitis and also in colonic neoplasms [16, 1 7]; therefore, it is by no means specific for acute diverticulitis. Our series also showed the nonspecific nature of this finding. Thickened colonic wall, however, is an important finding because it is easily recognized and could lead to the more important finding of protruding focus. In one patient, extraluminal gas from the perforation was seen as a focus of strong echo immediately behind the hypoechoic protruding focus from the cecum. Although this finding could be seen uncommonly, the direct evidence of small extraluminal gas and accompanying protruding focus strongly suggested microperforation with minute abscess, which is the hallmark of the diverticulitis [131. Although most of our patients were examined with a 3.5MHz transducer, high-resolution sonography with a 5- or 7.5MHz transducer can show the finer internal architecture of the sonographic findings of uncomplicated acute diverticulitis of the colon. In the cases of complicated diverticulitis with frank abscess formation, fistula, peritonitis, and free perforation, both sonography and CT can demonstrate findings of those complications [1 5, 1 8]. CT may be better suited to demonstrate gross changes in intraperitoneal and extraperitoneal spaces. Because the method of treatment is different in each condition, the differential diagnosis of right-sided diverticulitis and acute appendicitis is very important [9-i 2]. The sonographic findings of acute appendicitis are different from those of diverticulitis because a swollen appendix is shown as a tubular structure with a blind end [19], rather than as a round or oval abnormality, as in diverticulitis. It should be noted, however, that in one case of perforated appendicitis, a short segment of enlarged proximal appendix mimicked acute diverticulitis. In mesenteric adenitis and acute terminal ileitis, where right lower quadrant pain is commonly present, thickening of the ileum and multiple hypoechoic nodular foci of enlarged lymph nodes are found around the mesentery on sonography [20].

AND

ASCENDING

COLON

287

However, in our series of uncomplicated acute diverticulitis of the right colon, no lymph node enlargement was seen and only one case of ileal thickening was found. Differentiation of these two conditions, therefore, does not appear to be difficult. Follow-up sonography was helpful in showing resolution of the inflammatory change over a short period. This finding strongly supported the diagnosis of acute diverticulitis and also virtually excluded the possibility of colonic neoplasm. In summary, the main sonographic finding in uncomplicated acute diverticulitis of the right colon was a round or oval focus protruding from segmentally thickened colonic wall. The protruding focus was hypoechoic in the majority of cases and contained strong echoes in some cases. When this sonographic finding is seen without evidence of enlarged appendix, frank abscess, and peritoneal fluid collection in patients with right lower quadrant pain, uncomplicated acute diverticulitis of the right colon is strongly suggested.

REFERENCES 1 . Braunwald E, Isselbacher KJ, Petersdorf RG, Wilson JD, Martin JB, Fauci AS, eds. Harrison ‘s principles of internal medicine, 1 1 th ed. New York: McGraw-Hill, 1987:1292-1293 2. Schapira A, Leichtling JJ, wolf BS, Marshak RH, Janowitz HO. Diverticulitis of the cecum and right colon: clinical and radiographic features. Report of 18 cases. Dig Dis Sci 1958;3:351-383 3. Beranbaum SL, Zausner J, Lane B. Diverticular disease of the right colon. AJR 1972;i 15:334-348 4. Balthazar EJ, Megibow AJ, Gordon RB, Hulnick OH. Cecal diverticulitis: evaluation with CT. Radiology 1989;162:79-81 5. Scatarige JC, Fishman EK, Crist ow, Cameron JL, Siegelman SS. Diverticulitis of the right colon: CT observations. AJR 1987;i 48: 737-739 6. Townsend RR, Jeffrey RB Jr, Laing FC. Cecal diverticulitis differentiated from appendicitis using graded-compression sonography. AiR 1989; 152: 1229-1 230 7. Puylaert JBCM. Graded compression ultrasound in acute disease of the right lower quadrant. Semin US CT MR 1987;8:385-402 8. Gaensler EH, Jeffrey RB Jr. Laing FC, Townsend RR. Sonography in patients with suspected acute appendicitis: value in establishing alternative diagnoses. AiR 1989;152:49-51 9. Amngton P. Judd CS Jr. Cecal diverticulitis. Am J Surg 1981;142:56-59 1 0. wagner DE, Zollinger Rw. Oiverticulitis of the cecum and ascending colon. Arch Surg 1961;83: 124-131 1 1 . Fischer MG. Farkas AM. Oiverticulitis of the cecum and ascending colon. Dis Colon Rectum 1984;27:454-458 1 2. Gouge TH, Coppa GF, Eng K, Ranson JH, Localio SA. Management of diverticulitis of the ascending colon. 1 0 years’ experience. Am J Surg 1983;145:387-391 13. Diner WC, Barnhard HJ. Acute diverticulitis. Semin Roentgenol 1973; 8:415-431 14. Watanabe H, Enjoji M, Yao T. Pathomorphologic study of simple ulcer in ileocecal region (in Japanese). Stomach Intestine 1979;i 4 :749-767 1 5. Parulekar 5G. Sonography of colonic diverticulitis. J Ultrasound Med 1985;4:659-666 1 6. Yeh H-C, Rabinowitz JG. Granulornatous enterocolitis: findings by ultrasonography and computed tomography. Radiology 1983;149:253-259 17. Kelvin FM, Maglinte DOT. COIOreCtaI carcinoma: a radiologic and clinical review. Radiology 1987;i64:1-8 18. Hulnick OH, Megibow A), Balthazar EJ, NaidiCh OP. Bosniak MA. Cornputed tomography in the evaluation of diverticulitis. Radiology 1984;1 52: 491-495 19. Puylaert JBCM. Acute appendicitis: US evaluation using graded compression. Radiology 1986;158:355-360 20. Puylaert JBCM. Mesenteric adenitis and acute terminal ileitis: US evaluation using graded compression. Radiology 1986;16i :691 -695