CLINICAL IMAGING 1989;13:215-216 215

COMPUTED TOMOGRAPHY DIAGNOSIS OF PRIMARY AORTO-ENTERIC FISTULA

HAIM GUTMAN, MD, ISAAC RUSSO, MD, MARGALIT NEUMAN-LEVIN, MD, MENASHE HADDAD, MD, AND AVIGDOR ZELIKOVSKI, MD

Primary aorta-enteric fist&e are rare. Preoperative diagnosis is important but is difficult and cannot usually be confirmed by upper gastrointestinal se- ries, aortography and endoscopy. Computed tomog- raphy demonstrating an abdominal aortic aneurysm with air bubbles in its wall and “soft tissue” mass posteriorly should raise the possibility of penetra- tion of the aneurysm into the lumen of the bowel and related consequences (hematoma, sepsis, infected operating field).

KEY WORDS: Aneurysm; Aorto-enteric fistula; Aorto-duodenal fistula

Aorto-enteric fistula was first described by Sir Astley Cooper in 1829. Primary fistula is rare (0.1-0X% of abdominal aortic aneurysm) and is usually the end result of repeated pulsatile mechanical trauma (1) causing pressure necrosis of the duodenal wall (2,s). The clinical presentation of aorto-enteric fistula might include either upper gastrointestinal bleeding or septic signs (3), without the classical bursting pain (2).

Diagnostic modalities such as plain abdominal film, ultrasonography, upper gastrointestinal series, and even endoscopy and aortography give unsa- tisfactory results especially when the clinical picture is vague and the aneurysm is not palpated (2).

From the Department of Surnerv B, Vascular Unit, Institute of Radiology (I.R. -and M.N.-L.), fieiiinson Medical Center, Petah Tiqva, The Sackler School of Medicine, Tel Aviv Universitv, Israel.

Address reprint requests to: Haim Gutman, MD, Department of Surgery B, Beilinson Medical Center, Petah Tiqva 49 100, Israel.

Received September 16, 1988. 0 1989 by Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0899-7071189/$3.50

Computed tomography (CT) was previously re- ported as a possible means for improved diagnosis of secondary aorto-enteric fistula as well as graft sepsis with or without aorto-enteric penetration. This re- port demonstrates the role of CT in the diagnosis of primary aortic aneurysmo-enteric fistula.

CASE REPORT A i’i’-year-old man was admitted after 2 months of pain in his flanks and back, and 1 month of diffuse abdominal pain and intermittent fever. His medical history included inferior wall myocardial infarction (17 years ago) and aorto-coronary bypass with right carotid endarterectomy (4 years ago). On admission he was febrile and a large pulsatile abdominal mass was felt. He complained of nausea and vomited a small amount of coffee-ground material.

Trans-left femoral aortography was performed, demonstrating an infrarenal abdominal aortic aneu- rysm (AAA) without dissection. As these findings did not give full explanation of the clinical picture, CT was added and revealed the known AAA with a “pearl chain of air bubbles” inside the anterior wall of the aneurysm, as well as signs of retroperitoneal soft tissue mass (Figures 1 and 2). The patient was operated on with heavy antibiotic coverage. An aneu- rysmo-duodenal fistula with abscess in the aneu- rysm wall was found. The aneurysm was resected, the opening in the duodenum closed in two layers, and a Pantalon type PTFE (Gortex) graft placed with omentum interposition. Cultures from the aneurysm wall grew Streptococcus viridans. Postoperative course was stormy. Broad spectrum antibiotics were used for 2 weeks at the end of which Candida pneumonia and Candida sepsis were diagnosed. The patient recovered after intravenous treatment with amphothericin B.

216 GUTMAN ET AL CLINICAL IMAGING VOL. 13, NO. 3

FIGURE 1. “Pearl chain gas bubbles” [arrow) inside aortic aneurysm wall, adjacent to the duodenum with contrast material, and retroperitoneal hematoma (A, aortic lumen: D, duodenum; H, hematoma).

DISCUSSION When an aorto-duodenal fistula presents with upper gastrointestinal bleeding, endoscopic examination with high index of suspicion may give the diagnosis (4), but if a bleeding site cannot be endoscopically demonstrated, contrast medium studies and aor- tography are of little help (5).

Aorto-enteric fistulae were preoperatively diag- nosed by upper gastrointestinal series and aortogra- phy in 24-69% of patients in different series (6). CT was used in the past in order to investigate patients

FIGURE 2. Lower cross section, multiple gas bubbles. Note extent of hematoma. See Figure 1 legend for expla- nation of symbols.

with aortic grafts and suspicion of graft sepsis, pseudoaneurysm, or secondary graft-enteric fistula (7). In a few cases, air bubbles were demonstrated in the vicinity of the graft (8) and the diagnosis of periaortic graft infection was confirmed. A single gas bubble, anterior to the graft, within 10 days of an operation, is considered a normal finding (8, 9), but the presence of a growing number or multiple bub- bles, posterior to the graft, is agreed upon as being pathognomonic of an abscess around the graft (7). Gas in the aortic wall may be due to the presence of gas producing bacteria or due to a tiny valve-like connection to the duodenal lumen, or both (8).

In this case report, a primary aorto-duodenal fistula, gave typical CT signs: multiple air bubbles in the aortic aneurysm wall and posterior hematoma. Both seem to be pathognomonic of this diagnosis.

We call the attention of radiologists as well as vascular surgeons to these signs, because of the rarity of the disease and the fact that accurate preoperative diagnosis has special therapeutic importance (anti- biotic spectrum) in addition to their influence on the decisionmaking process [timing, possibility of ax- illo-bifemoral bypass before laparotomy (S)] and on the prognosis (10).

We recommend utilizing the CT for every AAA, especially when fever, sepsis, or unexplained upper gastrointestinal bleeding are among the presenting symptoms.

REFERENCES 1. Konomopoulos DC, Spands PK, Lazarides DP. Pathogenesis of

aorto-enteric fistula, an experimental study. Int Angiol 1986;5:33-37.

2. Gozzetti G, Poggioli G, Spolaore R, Faenza A, Cunsolo A, Selleri S. Aorto-enteric fistulae: spontaneous and after aor- toiliac operations. J Cardiovasc Surg 1984;25:420-426.

3. Gregson R, Craig 0. Aorto-enteric fistulae: the role of radiol- ogy. Clin Radio1 1983;34:65-72.

4. Vollnar JF, Kogel H. Aorto-enteric fistulas as postoperative complication. J Cardiovasc Surg 1987;28:479-484.

5. Kiernan PD, Fairolero PC, Hubert JP. Mucha P, Wallace RB. Aortic-graft-enteric fistula. Mayo Clin Proc 1980;55:731-738.

6. Ackroyd J. Williams TG, Thomas ML, Burnand KG. The diagnosis of.aortic graft-enteric fistulae by computed tomogra- phy. Br J Surg 1985;72:72-73.

7. Moulton S, Adams M, Johansen K. Aorto enteric fistula. Am J Surg 1986;151:607-611.

8. Haaga JR, Baldwin N, Reich NE, et al. CT detection of infected synthetic grafts: preliminary report of a new sign. AJR 1978;131:317-320.

9. Klein J, Gordon D, Glanz S, Lowery R, Sclafani S. Late CT detection of gas in an aortic graft: a normal postoperative finding. Comput Radio1 1986;10:193-195.

10. Buckels JAC, Fielding JWL, Black J, Ashton F, Slaney G. Significance of positive bacteria1 cultures from aortic aneu- rysm contents. Br J Surg 1985;72:440-444.