J Korean Radi이 Soc 1997; 37: 1091 -1096

CT Findings of Enteric Fistula 1

Jae Cheol Hwang, M.D. , Hyun Kwon Ha, M.D. , Young Cheol 、Veon， M.D. ，

Moon-Gyu Lee, M.D., Pyo-Nyun Kirn, M.D. , Yong Ho Auh, M.D.

Enteric fistulae result from gastrointestinal perforations in which communication is established between the site of perforation and another hollow viscus, potential space, or skin surface. Certain types of enteric fistulae are difficult to demonstrate by conven­tional radiographic methods, and CT is unique in its ability to demonstrate the extent and nature of extraluminal changes. The purpose of this study is to illustrate the CT findings of enteric fistulae occurring in a variety of abdominal and pelvic organs.

Index words : Fistula, gastrointestinal Gastrointestinal tract, CT

Enteric fistulae can develop as a result of a broad spectrum ofinflammatory or neoplastic processes any­where along the length of the gastrointestinal (GI) tract. As the signs and symptoms are varied and nonspecific, CT may be the initial imaging study performed on patients with fistulae. CT itself may not visualize a fistula , though certain CT findings may suggest the use of a barium stud y for diagnosis. In ad­dition, in patients with known enteric fistulae , CT may disclose other ancillary extraluminal abnormalities or complications, such as abscess formation , peritonitis, or lymphadenopathy, which barium study alone, might not reveal. This report illustrates the CT findings of various types of enteric fistulae and correlates them with those of conventional contrast studies.

Technical Considerations

Routine CT examinations of the abdomen often re­sult in inadequate evaluation of enteric fistulae , unless special effort is made to enhance their detection . In a certain type of fistula , modifications of CT scanning protoc이 can improve the overall diagnostic rate. In patients with biliary-enteric fistula , pre-enhanced

'Department of Diagnostic Radiology , Asan Medical Center, University ofUlsan C이 legeofMedicine

Received June 13, 1997; Accepted October 9, 1997

Address reprint requests to: Jae Cheol Hwang, M.D. , Department ofDiagnostic Radiology Asan Medical Center University of Ulsan College of Medicine ~ 388. 1 Poongnap-dong, Songpa-ku, SeouI138-040, Korea

Te l. 82-2-224- 4400 Fax.82-2-476-47 19

CT scanning may help determine the etiology. To as­sess the thickness of bowel wall and distinguish ab­scess from bowel loops, optimal bowel opacification and proper distention is essentiaL and to achieve this, several techniques may be employed (1). In suspected cases of pelvic fistulae , rectal contrast materials are routinely administered unless contraindicated by the presence of severe rectal pain and /or perineal disease To eliminate the possibility of abnormal air in the pel­vic organs, bladder catheterization and gynecologic examination should be avoided for 24 hours before CT examination. In the search for an abscess and in the evaluation of thickened bowel wall or mass, contrast materials are important, but if an enterovesical fistula is suspected , intravenous contrast enhancement should be avoided.

Eight-to-ten-millimeter collimation at lO-millimeter intervals covering the entire abdomen and pelvis is preferred initially ; this can be followed by contiguous scanning of the region of interest, using thinner sections. For demonstration ofthe fistula tract, delayed examination is often helpful.

Fistulous Communication between the GI Tract A variety of fistulae , including gastrocolic , gastro­

enteric, enteroenteric, enterocolic , or colocolic , may occur as a complication of benign or malignant disease of the GI tract; presentation varies depending on the cause and type of fistula. Pathognomic symptoms of

- 1091 -

gastrocolic or duodenocolic fistula are feculent vomi­ting or the passage of undigested food in the stool. In most cases , however, nonspecific symptoms, such as abdominal pain, malabsorption, diarrhea, and weight loss are the common features (2). For diagnosis of a fis­tula , traditional barium study of the GI tract is con­sidered to be the method of choice ; since, however, the exact nature and extent of the extraluminal disease process cannot be evaluated, the usefulness ofthis ap­proach is limited. CT, on the other hand , can provide important intraluminal and extraluminal pathologic findings as well as clues which can help differentiate

A

Jae Che이 Hwang. et al : CT Findings of Enteric Fistula

the underlying cause of a fistula. Malignant tumors that cause fistula are bulky and infiltrating (Fig. 1), and are often associated with metastatic foci in other intra-abdominal organs. Multiple fistula formation with mesenteric change is often characteristic of Crohn ’s disease (Fig. 2) (1 , 2)

The presence of these types of fistula can be diagnosed on CT by outlining the contrast-filled fistu­lous tract, but the diagnosis commonly depends on sec­ondary signs, such as flow diversion of orallyadmi­nstered contrast medium (Fig. 3), severe adhesion, thickening of adjacent bowel walL or an extralumi-

B

Fig. 1. Gastro-colic fistula in a patient with transverse colon carcinoma. A. Contrast-enhanced CT shows a large inhomogeneous mass of colon carcinoma in splenic flexure , directly invading the stomach. A fistulous tract fiUed with contrast material is suspected (arrows) B. A barium enema shows an annular type of luminal narrowing involving transverse colon and splenic flexure of colon with contrast-filled stomach due to presence of gastro-colic fistula (arrows)

1

A B

Fig. 2. Ileo-ileo-sigmoid fistula in a patient with Crohn’s disease. A. Contrast-enhanced CT shows irregular thickening of sigmoid colon and ilealloops with matted appearance due to severe adhesion. The sigmoid mesocolon is also diffusely infiltrated. Multiple fistulous tracts are suspected (arrows). B. A barium enema demonstrates multiple fistulous communications (arrows) between ilealloops and sigmoid colon.

- 1092 -

J Korean Radi이 Soc 1997; 37 : 1 091 - 1 096

A B Fig. 3. Gastro-colic fistula in a patient with history of subtotal gastrectomy. A. Contrast-enhanced CT shows nice depiction of a short fistulous tract between stomach and transverse colon (arrow). B. CT scan at the level of mid portion of kidneys shows relatively a large amount of oral contrast material in descending colon (D) as compared with that of ascending colon (A).

A B Fig. 4. Pancreatic pseudocyst with fistulous communication to transverse colon A. Contrast-enhanced CT shows a cystic mass (arrows) filled with contrast material and air in the transverse mesocolon due to fistulous communication between mass and transverse colon. The pancreas appears to be normal in size and contour. B. A barium enema confirms

nal soft tissue component containing air or contrast medium. For cases in which this diagnosis is suggested by CT, a barium study is indicated , with special atten­tion gi ven to the mapping of the fistula origin, course, or terminus.

Fistulous Communication between the Bowel andAbdominal Abscess Gastrointestinal fistulas and intra-abdominal absce­

sses commonly co-occur; some are probably causative in nature, and others are sequelae. The most frequent causes of intra-abdominal abscess with fistulous com­munication to the GI tract are recent GI tract surgery

with anastomotic leakage, and complications of pan­creatitis, diverticulitis, in f1ammatory bowel disease, trauma, or malignancy. CT may be used not only for the diagnosis of an abscess with a fistulous commu­nication to the GI tract but also to provide guidance for drainage. Although rarely seen, the presence in a CT image of orally-administered contrast medium within an abscess pocket is definite evidence offistulous com­munication to the GI tract (Fig. 4) (3). Other CT findi­ngs suggesting this type of fistulous communica­tion include obviously high air- f1uid levels within an abscess, or bowel wall thickening at the site of a fistula. In clinically suspected cases, however, the absence of

1093

Jae Ch∞I Hwang, et al : CT Findings of Enteric Fistula

A B Fig. S. Fistulous communication of the bowel with intraperitoneal abscess resulting from perforated appendicitis. A. Contrast-enhanced CT shows an abscess with irregular and thick wall (arrows), closely attaching to adjacent bowel. There is no evidence of air or contrast collection within abscess cavity. B. Cavitogram through the needle inserted percutaneously 3 days after CT examination shows an abscess cavity (A) with fistulous communication to ileal loop (1)

Fig. 6. A 82-year-old woman with cholecysto-duodenal fistula caused by squamous cell carcinoma of gallbladder carcinoma . Contrast-enhanced CT shows irregular thick­ening of gallbladder wall (arrows) with air and contrast material in the lumen.

Fig. 7. A 56-year-old man with cholecysto-duodenal fis­tula due to perforated acute cholecystitis. Contrast­enhanced CT shows distended gallbladder with air- f1uid level (open arrows) in the lumen and discontinuity of the wall in association with pericholecystic air and f1uid col­lection (solid arrows). The interface between gallbladder and duodenum is completely lost with thickened duo­denal wall

Fig. 8. Recto-vesical fistula in a patient with Crohn ’ s dis­ease. Contrast-enhanced CT shows a small amount of air (arrows) in the bladder as well as irregular thickening of the posterior bladder wall (arrowheads) and rectosigmoid colon with complete loss of interface between these two organs.

- 1094 -

J Korean Radi이 Soc 1997; 37: 1091 -1096

A B Fig. 9. Recto-vesico-uterine fistula in a patient with cervix cancer. A. Contrast-enhanced CT shows contrast collection in uterine cavity (U) with a fistulous tract (arrows) between bladder (B) and uterine cavity. The tumor diffusely infiltrates the uterus and bladder with complete loss of interface. B. Contrast-enhanced CT scan 2 cm cephalad to (A) shows air collection (arrow) in the uterine cavity due to rectouterine fistula. The interface between uterus and rectum is also lost with focal thickening of the rectal walL

v

ß ..

A B Fig. 10. Rectovesical fistula in a patient with perforated rectal cancer. A. Contrast-enhanced CT shows direct communication (arrow) between bladder and necrotic tumor (arrowheads) in rectovesical pouch . The posterior wall of the bladder is irregularly thickened as well B. Lateral view of the pelvic cavity during intravenous pyelogram shows contrast filling of rectum (R) and necrotic tumor through fistulous communication from the bladder (B). The posterior wall of the bladder is irregularly indented and invaded by tumor (arrowheads)

air and f1uid does not exclude the possibility of an internal fistula (Fig. 5).

Fistu/ous Communication to the Biliary Tract In 90 % of cases, spontaneous communication be­

tween the biliary and GI tracts occurs as a complication of the presence of stones in the biliary tract; 10%, however, are caused by peptic ulcer, tumor, or trauma. The duodenum is the most common site of biliary-en­teric fistulae , and most others are found in the stomach or colon. Ascending cholangitis, GI bleeding, diarrhea, or malabsorption may complicate biliary-enteric fistu-

lae, though a fistulous tract can act as a physiological conduit or permanant alternate route for the excre­tion of bile. For these reasons, recognition of this type of fistula is essential for proper management.

Characteristic CT findings of biliary-enteric fistula are the presence of air or orally-administered contrast medium in the biliary tree (Figs. 6 and 7) (5); CTcan demonstrate air in this location with exquisite sensi­tivity. In addition to spontaneous biliary fistulae , how­

ever, previous surgery, patulous sphincter of Odd i,

and ascending cholangitis with gas-forming organisms should be considered in differential diagnosis. Other

- 1095 -

ancillary findings include bowe1 wall thickening at the site of the fistu1a termination and surrounding in­f1ammatory change (Fig. 7). Occasionally, CT is a1so he1pfu1 in eva1uating the primary cause of a biliary-en­teric fistu1a

Fistulous Communication to the Genitouri­naryTract Fistu10us communication between the GI and

genitourinary tract can deve10p as a result of compli­cations arising from diverticulitis, co1orecta1 malig­nancy, Crohn ’s disease, gyneco1ogic malignancy, pre­vious pe1vic surgery or irradiation, or trauma. Because of the close proximity of its anatomic 10cation, the ma­jority of fistu1ae occur in the pelvic cavity and include the enterovesica l, rectourethral, enterouterine, and enterovagina1 types. In such cases, patients usually present with urinary symptoms which suggest diag­nosis; they are re1ated to diversion of urinary or feca1 f1ow, such as fecaluria, pneumaturia, or passing feces or urine via the vagina.

For eva1uating this type of fistu1a, CT has proven to be more sensitive and acccurate than conventiona1 co-

Jae Cheol Hwang. et al : CT Findings of Enteric Fistula

ntrast studies (5); unless a pathologic pathway is di­rectly demonstrated (5), the key finding is the depic­tion of air or orally-administered contrast medium in the genitourinary tract (Figs. 8 and 9). Other ancillary CT findings include an extraluminal mass adjacent to the bowel, foca1 wall thickening of the involved organs, and comp1ete 10ss of the intervening fat p1ane between the GI and genitourinary tract (Fig. 10).

References

1. Gore RM. Cross-sectional imaging of inf1ammatory bowel dis­ease. Radio/ C/in North Am 1987; 25(1): 11 5-131

2. Pichney LS , Fantry GT, Graham SM. Gastrocolic and duo­denocolic fistula in Crohn disease. J C/in Gastroentero/ 1992; 15 (3): 205-211

3. Fukuya T, Hawes DR, Lu CC. CT of abdominal abscess with fis­tulous communication to the gastrointestinal tract. J Comput

Assist Tomogr 1991; 15(3) ‘ 445-449 4. Harkavy LA, Balthazar EJ , Naidich DP. CT diagnosis of cho­

lecystod uodenal fistula. Am J Gastroentero/ 1985; 80 ‘ 569-571 5. Kuhlman JE, Fishman EK. CT evaluation of enterovaginal and

vesicovaginal fistulas. J Comput Assist Tomogr 1990 ; 14(3) : 390-394

대한밤시선의학호|지 199? ;3?: 1091-1096

장루의 CT 소견1

l 울산대학교 의과대학 서울중앙병원 진단방사선과학교실

황재철·하현권·원영철·이문규·검표년·오용호

장루(enteric fistu1a)는 위장관 천공에 의해 발생하며 천공 부위와 다른 장관， 복강내 공간， 또는 피부와 연결

된 것이다. 어떤 형태의 장루는 종래의 방사선 검사로 증명하기가 어려울 때가 있다. 전산화단층촬영은 장관 밖

의 변화와 침범 부위를 평가하는데 탁월한 검사 방법이다. 이 임상 화보에서 복강과 골반강 장기에 발생한 다양

한 장루에 대한 전산화단층촬영 소견을 기술하고자 한다

- 1096