- Email: [email protected]
Aortoenteric fistula to the sigmoid colon—case report
ORIGINAL REPORTS
Aortoenteric Fistula to the Sigmoid Colon—Case Report Rodrigo O. Perez, MD,* Fabio F. Katayama, MD,† Cláudio Bresciani, MD,‡ Carlos E. Jacob, MD,‡ Roger B. Coser, MD,¶ Paulo R. A. Alves, MD,* Angelita Habr-Gama, MD,* Joaquim J. Gama-Rodrigues, MD,‡ Desidério R. Kiss, MD,* and Mario Cimelli Jr., MD** *Colorectal Surgery Division, Department of Gastroenterology; †Preventive Medicine Department; ‡Surgery of the Alimentary Tract Division, Department of Gastroenterology; ¶Surgery Department, School of Medicine, University of São Paulo, São Paulo, Brazil; and **Vascular Surgery Department, Hospital Alemão Oswaldo Cruz Aortoenteric fistula is defined as a communication between the aorta and any adjacent segment of the bowel. It may be primary or secondary. The former occurs de novo in patients with intestinal or vascular diseases, whereas secondary aortoenteric fistula is a rare and dreadful complication of aortic reconstruction with vascular prosthesis. We report a case of a 62-year-old man who presented to the emergency department with acute rectal bleeding. The patient had previous aortoiliac surgery with the utilization of an aorto-bifemoral vascular graft. Diagnosis of secondary aortoenteric fistula was made between the aortoiliac graft and sigmoid colon. After exploratory laparotomy, Hartmann’s procedure, excision of the graft, oversewing of the aortic stump, and axilobifemoral bypass were successfully performed. This study reports a rare type of secondary aortoenteric fistula to the left colon, and it describes an unusual and successful surgical treatment. (Curr Surg 62:49-54. © 2005 by the Association of Program Directors in Surgery.)
though a serious and life threatening condition, it occurs only in 0.3% to 5.9% of all patients who undergo aortic reconstruction.6,7 The most common gastrointestinal site for the development of an AEF is the duodenum, which is involved in 87% of the cases, followed by small bowel, and other sites such as esophagus, stomach, and appendix.4,8-11 Large bowel is rarely affected.12 Early diagnosis is essential for a successful outcome in spite of the lethal nature of AEF. Also, definitive treatment requires immediate surgical intervention.11,13,14 Even though new diagnostic methods have been developed allowing early diagnosis, the mortality from this disease remains extremely high.4,15-19 The aim of this study is to report a rare type of secondary AEF to the left colon, which was effectively diagnosed and successfully treated, allowing a complete recovery from this dreadful complication.
KEY WORDS: aorta, sigmoid colon, fistula, rectal bleeding,
vascular prosthesis
INTRODUCTION Aortoenteric fistula (AEF) is defined as a communication between the aorta and any adjacent segment of the bowel. Although Sir Astley Cooper1 was the first to draw attention to the complication of abdominal aneurysm that he called “arterioenteric fistula,” the first formal case report of an aortoenteric fistula was presented in 1843 by Salmon.2 It may be classified into primary or secondary AEF. The former occurs de novo in patients with intestinal or vascular diseases, whereas secondary AEF is a rare and dreadful complication after aortic reconstruction with vascular prosthesis.3-5 Secondary AEF is more frequent than primary AEF.5 Al-
Correspondence: Inquiries to Rodrigo Oliva Perez, Rua Inhambu 1125, apt. 141, Zip 04520013, São Paulo-SP, Brazil; fax: 55-11-38848845; e-mail: [email protected]
CASE REPORT A 62-year-old man presented to the emergency department with intermittent rectal bleeding for the last 15 days. The bleeding became more intense in the last 12 hours and was associated with intense perianal pain. There was no history of fever or weight loss. The patient was hemodynamically stable and physical examination showed only mild paleness. Hematological findings confirmed anemia (Hb ⫽ 8.7 g/dl; Ht ⫽ 26%). The patient had previous history of an aortoiliac aneurysm managed by an elective surgical intervention, with interposition of an aortobiiliac Dacron graft with no immediate postoperative complications sixteen years earlier. Esophagogastroduodenoscopy was normal. Abdominal ultrasonography showed a great vascular mass in the hypogastric region (approximately 50 cm3) (Fig. 1), whereas abdominal computed tomography (CT) scans showed a right commoniliac aneurysm (5 cm diameter) (Fig. 2) in direct contact with the bladder and the sigmoid colon (Figs. 3 and 4). Colonoscopy
CURRENT SURGERY • © 2005 by the Association of Program Directors in Surgery Published by Elsevier Inc.
0149-7944/05/$30.00 doi:10.1016/j.cursur.2004.06.018
49
FIGURE 1. Ultrassonographic illustration of the great vascular mass.
revealed blood in the rectum, sigmoid stenosis secondary to an extrinsic pulsate compression, and hematic infiltration of the sigmoid wall (Fig. 5). Blood cultures were positive for Streptococus faecalis. Once AEF was diagnosed, the patient underwent immediate laparotomy. Intraoperative findings included a great pulsatile mass in direct contact with the sigmoid colon, which showed signs of hematic infiltration of its wall. Mobilization of the sigmoid colon confirmed the erosion of the pseudoaneurysm, and bleeding was controlled after clamping of the aorta and iliac arteries. Then, full dissection of the aorta, excision of the entire aortic graft, oversewing of the aortic stump, sigmoidectomy, and end-colostomy (Hartmann’s procedure) were performed (Fig. 6). An extra-anatomic bypass was created using axilofemoral Dacron graft and a femoro-femoral saphenous vein graft to
FIGURE 2. Computed tomography scan shows a right common-iliac aneurysm (a) and a normal left common-iliac artery (b). 50
FIGURE 3. Computed tomography scan shows a mass (b) causing extrinsic compression of the bladder (a) and the large bowel (c).
reestablish blood flow to lower extremities. Total aortic clamping time was approximately 60 minutes. Pathological examination of the colon showed ischemic necrosis of the sigmoid colon, large mesocolic hematoma, and a rectal segment with alterations secondary to acute ischemia. The patient developed bilateral lower limb compartmental syndrome requiring immediate bilateral fasciotomies at the end of the operation. The patient was discharged from the hospital on the twenty-fourth postoperative day. He had no neuromuscular defi-
FIGURE 4. Computed tomography scan shows a mass (a) causing extrinsic compression of the bowel (b). A plane between both structures cannot be clearly identified. CURRENT SURGERY • Volume 62/Number 1 • January/February 2005
FIGURE 5. Colonoscopy reveals sigmoid stenosis secondary to an extrinsic pulsatile compression and hematic infiltration in the sigmoid wall.
cits or infectious complications. Six months later, he was submitted to colostomy takedown and recovered uneventfully.
DISCUSSION Aortoenteric fistula is a rare but deadly complication after aortic reconstructive surgery with prosthesis, and its incidence varies from 0.3% to 5.9% in literature.6,7 In terms of the segment of the gastrointestinal tract involved, the majority of AEF (87%) occurs between the aorta and the third or fourth portions of the duodenum. Jejunum is involved in 7%, ileum in 4%, and colon in only 2% of the cases.4,8-11 The proximal suture line between the prosthesis and aorta is the most common place in the formation of fistulas. Aortoenteric fistula related to the distal suture line of the prosthesis is rare in the literature.4,6,10 Aortoenteric fistulas are more likely to occur subsequent to operation for ruptured aortic aneurism than after elective aneurysmectomy.20 The incidence is almost insignificant when the graft is placed for aortoiliac occlusive disease.20 The prosthesis material does not seem to influence the incidence of fistula, but the aortic sutures involving silk line used to be more likely related to the disruption of the suture line and the formation of pseudoaneurysms in comparison with more recent suture materials.11,20 Several mechanisms have been proposed for the formation of AEF. The primary event is still obscure and controversial. The presence of the aortic graft is necessary for the development of secondary AEF, but not sufficient.21-24 Two main mechanisms have been related with the pathogenesis of this disease: infection (with inflammatory response) and mechanical disturbances.4,5,20 CURRENT SURGERY • Volume 62/Number 1 • January/February 2005
FIGURE 6. The patient underwent laparotomy with full dissection of the aorta, excision of the entire aortic graft, oversewing of the aortic stump, sigmoidectomy, and end-colostomy (Hartmann’s procedure).
The prosthesis infection is associated with the rupture of the suture line and formation of pseudoaneurysm, which then erodes into the overlying bowel.4,11,20 This may consist in total or partial separation of the nonelastic graft wall and the abdominal aorta. Once the graft is seeded with bacteria, fistulization occurs in 12% to 33% of the cases.25 In the case reported above, fistulization between colon and aorta/iliac artery occurred in the distal suture line, an infrequent observation. Infection, however, is not the only primary event related to the fistula formation. Mechanical factors can also be implicated in its pathogenesis,4,20 with the adherence of the bowel to the graft, formation of dense adhesions, and then mechanical erosion of the bowel by the noncompliant pulsatile graft. Because of this, some authors advocate the importance of anastomosis coverage with peritoneal tissues, such as the greater omentum, in order to prevent bowel adherence to the graft.15,19,26 Some microorganisms isolated in blood cultures of patients are frequently associated with this condition such as Staphylococcus aureus, Bacteroides fragilis, Streptococus faecalis, and many Escherichia coli subtypes. However, there is no correlation between specific bacterial infection of suture line, pseudoaneurysm formation, or severity of the infectious process.25 Since the first AEF reported cases, dated from the last centu51
ry,1 to more recent ones, symptoms related with primary or secondary AEF have not changed.4,20 Clinical presentation involves an infectious or hemorrhagic component, sometimes combined. Manifestations of the septic component are usually fever and malaise, ultimately progressing to shock in unrecognized cases.4 Another frequent manifestation is gastrointestinal bleeding, that will be manifested according to the segment of the bowel involved.20,27 This can lead to hypotension or even to hemorrhagic shock.27 Abdominal pain and anemia may also be present.4,6,20 An aggressive diagnostic evaluation and a high index of suspicion are required for a successful outcome, because it allows early diagnosis and prompt surgical intervention. The primary condition to consider AEF is previous abdominal aortic surgery added to any clinical manifestation listed above. In spite of the low incidence of the disease and different clinical manifestations, accurate preoperative diagnosis is not always easily established, even though there has been some advance in imaging techiniques.28 Endoscopy may be helpful, even though it frequently does not identify the fistula. On the other hand, the absence of other lesions responsible for gastrointestinal bleeding supports the initial diagnosis.12 Endoscopy may reveal the site of bleeding in 80% of those examined.29 As the duodenum is the most common segment of the gastrointestinal tract involved in AEF, esophagogastroduodenoscopy is always recomended.5,8,30 Colonoscopy is rarely useful.12 Computed tomography (CT) scans are the most useful test to diagnose infected AEF.28,30,31 Abdominal CT scans may reveal an aortic prosthesis surrounded by inflammation containing small air pockets, a situation that has been associated with graft infection and fistula formation.18 A recent study showed a sensitivity rate of 83.3% for this imaging technique, with specificity and accuracy rates of 99.7% and 93.7%, respectively.28 Other diagnostic methods such as technetium-99m pertechnetate scanning and labeled-leukocyte scintigraphy can be useful in diagnosis of infected AEF, determination of the extent of disease, and selection of the treatment modality, but experience with them is limited.18,32,33 The sensitivity of magnetic resonance imaging in detection of perigraft infection has not been thoroughly investigated but is probably similar to that of CT.31 Barium contrast studies and aortography generally are not helpful in diagnosing either type of fistula. In true aortoenteric fistula, contrast aortography will not demonstrate a fistula if the communication between the graft and the bowel is not large enough or is temporally occluded by a thrombus.18 Ultrasound is particularly important when clinical presentation is atypical or when general medical conditions are critical. In the case reported above, colonoscopy was very useful for the diagnosis, revealing blood in the rectum, sigmoid stenosis secondary to an extrinsic pulsate compression, and hematic infiltration of the sigmoid wall, indicating the probable ana52
tomic location of the fistula. Computed tomography confirmed AEF and allowed prompt surgical intervention. Once AEF is suspected, immediate surgical intervention is necessary. In those patients who were not managed by urgent laparotomy, mortality rate was 100%.4 The type of surgery will depend on the location, extension, and hemodynamic condition of the patient. Complete aortic graft removal is highly recommended, because any prosthetic material inoculated with bowel organisms is a potential source of persistent infection.18 Attempts have been reported in which the graft was repaired or replaced “in situ.” However, these studies have noted early uniform incidence of enteric contamination of the graft and high mortality rates associated with subsequent sepsis.4 The intestinal defect must also be repaired.18,20 The choice of Hartmann’s procedure in the case reported allowed immediate fistula control with minimum intraperitoneal contamination by avoiding a primary enteric anastomosis. This was crucial to minimize lower limb ischemia and to permit early revascularization. After infection and hemorrhagic sources have been controlled, an aortic stump is created by oversewing the remaining native aorta. Reestablishment of blood flow to the lower extremities is usually accomplished by an axillary-bifemoral bypass. The aortic stump may be covered with omentum, peritoneum, or even a muscle flap to prevent recurrent fistulization.9 Even after successful surgical treatment, perioperative mortality ranges between 25% and 90% and is associated with major complications.34 In the last years, a new and less invasive therapeutic method has been developed and studied for the treatment of AEF: endovascular repair. Although still controversial,35 benefits in terms of bleeding and infection control have been shown in highly selected patients.34 In the setting of gross infection, it may also be considered in high-risk patients as a bridge to more definitive treatment after hemodynamic stabilization.34,36,37 New surgical techniques to prevent or even to treat AEF have been described by many authors, such as the coverage of the anastomosis with a vascular prosthesis tailored ring, but experience with them is limited and more studies are needed.38
CONCLUSION Aortoenteric fistula is a rare but life-threatening complication of abdominal aortic surgery. Diagnosis may be difficult because of its low incidence and diversity in clinical manifestations. Aortoenteric fistula should be considered in any patient with previous abdominal aortic surgery who presents with acute gastrointestinal hemorrhage. Even though the duodenum is the most common segment involved in AEF, large bowel may also be affected and should be considered especially when esophagogastroduodenoscopy is normal. Irrespective of the segment of the bowel involved, immediate surgery is highly recommended.
ACKNOWLEDGMENT The authors acknowledge Marcos Retzer for the illustrations. CURRENT SURGERY • Volume 62/Number 1 • January/February 2005
REFERENCES 1. Cooper A. Lectures on the Principles and Practice of Surgery
with Additional Notes and Cases by F. Tyrell. 5th ed. Philadelphia, PA: Haswell, Barrington & Haswell; 1839. 2. Salmon M. Aneuryme de l=aorte ventrale: Most par rup-
16. Busuttil SJ, Goldstone J. Diagnosis and management of
aortoenteric fistulas. Semin Vasc Surg. 2001;14:302-311. 17. Constans J, Midy D, Baste JC, Demortiere F, Conri C.
Secondary aortoduodenal fistulas: report of 7 cases. Rev Med Intern. 1999;20:121-127.
ture de la poche arterille dans le duodenum. Bull Soc Anat. 1843;283:18-28.
18. Dachs RJ, Berman J. Aortoenteric fistula. Am Fam Phys.
3. Sweeney, MS, Gadacz MD. Primary aortoduodenal fis-
19. Umpleby HC, Britton DC, Turbull AR. Secondary arte-
1992;45:2610-2616.
tula: manifestation, diagnosis, and treatment. Surgery. 1984;96:492-497.
rio-enteric fistulae: a surgical challenge. Br J Surg. 1987; 74:256-259.
4. Bunt TJ. Synthetic vascular graft infections II. Graft-en-
20. Busuttil RW, Rees W, Baker JD, Wilson SE. Pathogenesis
teric erosions and graft-enteric fistulas. Surgery. 1983;94: 1-9.
of aortoduodenal fistula: experimental and clinical correlates. Surgery. 1979;85(1):1-13.
5. Antinori CH, Andrew CT, Santaspirt JS, et al. The many
21. Kiev J, Kerstein MD. Primary aortoenteric fistulas: a case
faces of aortoenteric fistula. Am Surg. 1996;62:344-349. 6. Moulton S, Adams M, Johansen K. Aortoenteric fistula. A
7 year urban experience. Am J Surg. 1986;151:607-611. 7. Gabriel BF, Labios GM, Ibanez GL, Facila RL, Carbonell
report. South Med J. 1994;87:825-826. 22. Gelister JSK, Fox JA. Primary aortoenteric fistula. J R Soc
Med. 1987;80:459-460. 23. Calligaro KD, Bergen WS, Savarese RP, Westcott CJ.
CC. Aortoenteric fistula secondary to aortobifemoral prosthesis infection. Ann Med Int. 2002;19:246-250.
Primary aortoduodenal fistula due to septic aortitis. J Cardiovasc Surg (Torino). 1992;33:192-197.
8. Garret HE, Beall AC, Jordan GL, DeBakey ME. Surgical
24. Barned H, Fletcher PR, Carpenter R. Primary aortoen-
considerations of massive gastrointestinal tract hemorrhage caused by aortoduodenal fistula. Am J Surg. 1963; 105:6-11.
25. Gutowski P. Aortoiliac graft infection as a diagnosis and
9. D’Souza CR, Hebert RJ, Allen FT, Kilam S. Aortoenteric
teric fistula. West Indian Med J. 1995;44:93-95. treatment problem. Ann Acad Med Stetin. 1998;(suppl 41):71-72.
fistula: case review and a new surgical technique. Can J Surg. 1987;30:415-417.
26. England DW, Simms MH. Recurrent aorto-duodenal fis-
10. Grande JP, Ackermann DM, Edwards WD. Aortoenteric
27. Armitage NC, Ballantyne KC. Primary aortoenteric fis-
fistulas. A study of 28 autopsied cases spanning 25 years. Arch Pathol Lab Med. 1989;113:1271-1275.
tula due to recurrent colorectal cancer. Report of a case. Dis Colon Rectum. 1990;33:148-149.
11. Connoly JE, Kwaan JHM, McCart M, Brownell DA, Le-
28. Iino M, Kuribayashi S, Imakita S, et al. Sensitivity and
vine EF. Aortoenteric fistula. Ann Surg. 1981;194:402412.
specificity of CT in the diagnosis of inflammatory abdominal aortic aneurysms. J Comput Assist Tomogr. 2002;26: 1006-1012.
12. Cranston D, Vowles KDJ. Aorto-duodenal and subse-
quent aorto-colonic fistula following operation for ruptured aortic aneurysm. Br J Surg. 1980;67:649-650. 13. Trout HH III, Kozloff L, Giordano JM. Priority of revas-
cularization in patients with graft enteric fistulas, infected arteries or infected arterial prostheses. Ann Surg. 1984; 199:669-683. 14. Alimi Y, Juhan C. Complications tardives des prothéses
aortiques sous-renales: faux anevrismes et fistules aortodigestives. J Mal Vasc. 1995;20:172-176. 15. Thomas WEG, Baird RN. Secondary arterio-enteric fis-
tulae: towards a more conservative approach. Br J Surg. 1986;73:875-878. CURRENT SURGERY • Volume 62/Number 1 • January/February 2005
tula: a final solution? Eur J Vasc Surg. 1990;4:427-429.
29. Champion MC, Sullivan SN, Coles JC, Goldbach M,
Watson WC (1982). Aortoenteric fistula. Incidence, presentation recognition, and management. Ann Surg. 1982; 195:314-317. 30. Higgins RSD, Steed DL, Zajko AB, Sumkin J, Webster
MW. Computed tomographic scan confirmation of paraprosthetic enteric fistula. Am J Surg. 1991;162:36-38. 31. Orton DF, LeVeen RF, Saigh JA, et al. Aortic prosthetic
graft infections: radiologic manifestations and implications for management. Radiographics. 2000;20:977-993. 32. Ganatra RH, Haniffa MA, Hawthorne AB, Rees JI. Aor-
toenteric fistula complicating an infected aortic graft: di53
agnosis by leukocyte scintigraphy. Clin Nucl Med. 2001;26:800-801. 33. Lenzo NP, Male TA, Turner JH. Aortoenteric fistula on
(99m)Tc erythrocyte scintigraphy. AJR Am J Roentgenol. 2001;177:477-478. 34. Burks JA Jr, Faries PL, Gravereaux EC, Hollier LH, Marin
ML. Endovascular repair of bleeding aortoenteric fistulas: a 5-year experience. J Vasc Surg. 2001;34:1055-1059.
36. Chuter TA, Lukaszewicz GC, Reilly LM, et al. Endovas-
cular repair of a presumed aortoenteric fistula: late failure due to recurrent infection. J Endovasc Ther. 2000;7:240244. 37. Grabs AJ, Irvine CD, Lusby RJ. Stent-graft treatment for
bleeding from a presumed aortoenteric fistula. J Endovasc Ther. 2000;7:236-239.
35. Deshpande A, Lovelock M, Mossop P, Denton M, Vidov-
38. Demaria RG, Borie F, Albat B, Frapier JM, Millat B,
ich J, Gurry J. Endovascular repair of an aortoenteric fistula in a high-risk patient. J Endovasc Surg. 1999;6:379384.
Chaptal PA. Simple surgical technique to prevent direct secondary aortoenteric fistulas. J Cardiovasc Surg (Torino). 2002;43(1):99-101.
54
CURRENT SURGERY • Volume 62/Number 1 • January/February 2005
Aortoenteric Fistula to the Sigmoid Colon—Case Report Rodrigo O. Perez, MD,* Fabio F. Katayama, MD,† Cláudio Bresciani, MD,‡ Carlos E. Jacob, MD,‡ Roger B. Coser, MD,¶ Paulo R. A. Alves, MD,* Angelita Habr-Gama, MD,* Joaquim J. Gama-Rodrigues, MD,‡ Desidério R. Kiss, MD,* and Mario Cimelli Jr., MD** *Colorectal Surgery Division, Department of Gastroenterology; †Preventive Medicine Department; ‡Surgery of the Alimentary Tract Division, Department of Gastroenterology; ¶Surgery Department, School of Medicine, University of São Paulo, São Paulo, Brazil; and **Vascular Surgery Department, Hospital Alemão Oswaldo Cruz Aortoenteric fistula is defined as a communication between the aorta and any adjacent segment of the bowel. It may be primary or secondary. The former occurs de novo in patients with intestinal or vascular diseases, whereas secondary aortoenteric fistula is a rare and dreadful complication of aortic reconstruction with vascular prosthesis. We report a case of a 62-year-old man who presented to the emergency department with acute rectal bleeding. The patient had previous aortoiliac surgery with the utilization of an aorto-bifemoral vascular graft. Diagnosis of secondary aortoenteric fistula was made between the aortoiliac graft and sigmoid colon. After exploratory laparotomy, Hartmann’s procedure, excision of the graft, oversewing of the aortic stump, and axilobifemoral bypass were successfully performed. This study reports a rare type of secondary aortoenteric fistula to the left colon, and it describes an unusual and successful surgical treatment. (Curr Surg 62:49-54. © 2005 by the Association of Program Directors in Surgery.)
though a serious and life threatening condition, it occurs only in 0.3% to 5.9% of all patients who undergo aortic reconstruction.6,7 The most common gastrointestinal site for the development of an AEF is the duodenum, which is involved in 87% of the cases, followed by small bowel, and other sites such as esophagus, stomach, and appendix.4,8-11 Large bowel is rarely affected.12 Early diagnosis is essential for a successful outcome in spite of the lethal nature of AEF. Also, definitive treatment requires immediate surgical intervention.11,13,14 Even though new diagnostic methods have been developed allowing early diagnosis, the mortality from this disease remains extremely high.4,15-19 The aim of this study is to report a rare type of secondary AEF to the left colon, which was effectively diagnosed and successfully treated, allowing a complete recovery from this dreadful complication.
KEY WORDS: aorta, sigmoid colon, fistula, rectal bleeding,
vascular prosthesis
INTRODUCTION Aortoenteric fistula (AEF) is defined as a communication between the aorta and any adjacent segment of the bowel. Although Sir Astley Cooper1 was the first to draw attention to the complication of abdominal aneurysm that he called “arterioenteric fistula,” the first formal case report of an aortoenteric fistula was presented in 1843 by Salmon.2 It may be classified into primary or secondary AEF. The former occurs de novo in patients with intestinal or vascular diseases, whereas secondary AEF is a rare and dreadful complication after aortic reconstruction with vascular prosthesis.3-5 Secondary AEF is more frequent than primary AEF.5 Al-
Correspondence: Inquiries to Rodrigo Oliva Perez, Rua Inhambu 1125, apt. 141, Zip 04520013, São Paulo-SP, Brazil; fax: 55-11-38848845; e-mail: [email protected]
CASE REPORT A 62-year-old man presented to the emergency department with intermittent rectal bleeding for the last 15 days. The bleeding became more intense in the last 12 hours and was associated with intense perianal pain. There was no history of fever or weight loss. The patient was hemodynamically stable and physical examination showed only mild paleness. Hematological findings confirmed anemia (Hb ⫽ 8.7 g/dl; Ht ⫽ 26%). The patient had previous history of an aortoiliac aneurysm managed by an elective surgical intervention, with interposition of an aortobiiliac Dacron graft with no immediate postoperative complications sixteen years earlier. Esophagogastroduodenoscopy was normal. Abdominal ultrasonography showed a great vascular mass in the hypogastric region (approximately 50 cm3) (Fig. 1), whereas abdominal computed tomography (CT) scans showed a right commoniliac aneurysm (5 cm diameter) (Fig. 2) in direct contact with the bladder and the sigmoid colon (Figs. 3 and 4). Colonoscopy
CURRENT SURGERY • © 2005 by the Association of Program Directors in Surgery Published by Elsevier Inc.
0149-7944/05/$30.00 doi:10.1016/j.cursur.2004.06.018
49
FIGURE 1. Ultrassonographic illustration of the great vascular mass.
revealed blood in the rectum, sigmoid stenosis secondary to an extrinsic pulsate compression, and hematic infiltration of the sigmoid wall (Fig. 5). Blood cultures were positive for Streptococus faecalis. Once AEF was diagnosed, the patient underwent immediate laparotomy. Intraoperative findings included a great pulsatile mass in direct contact with the sigmoid colon, which showed signs of hematic infiltration of its wall. Mobilization of the sigmoid colon confirmed the erosion of the pseudoaneurysm, and bleeding was controlled after clamping of the aorta and iliac arteries. Then, full dissection of the aorta, excision of the entire aortic graft, oversewing of the aortic stump, sigmoidectomy, and end-colostomy (Hartmann’s procedure) were performed (Fig. 6). An extra-anatomic bypass was created using axilofemoral Dacron graft and a femoro-femoral saphenous vein graft to
FIGURE 2. Computed tomography scan shows a right common-iliac aneurysm (a) and a normal left common-iliac artery (b). 50
FIGURE 3. Computed tomography scan shows a mass (b) causing extrinsic compression of the bladder (a) and the large bowel (c).
reestablish blood flow to lower extremities. Total aortic clamping time was approximately 60 minutes. Pathological examination of the colon showed ischemic necrosis of the sigmoid colon, large mesocolic hematoma, and a rectal segment with alterations secondary to acute ischemia. The patient developed bilateral lower limb compartmental syndrome requiring immediate bilateral fasciotomies at the end of the operation. The patient was discharged from the hospital on the twenty-fourth postoperative day. He had no neuromuscular defi-
FIGURE 4. Computed tomography scan shows a mass (a) causing extrinsic compression of the bowel (b). A plane between both structures cannot be clearly identified. CURRENT SURGERY • Volume 62/Number 1 • January/February 2005
FIGURE 5. Colonoscopy reveals sigmoid stenosis secondary to an extrinsic pulsatile compression and hematic infiltration in the sigmoid wall.
cits or infectious complications. Six months later, he was submitted to colostomy takedown and recovered uneventfully.
DISCUSSION Aortoenteric fistula is a rare but deadly complication after aortic reconstructive surgery with prosthesis, and its incidence varies from 0.3% to 5.9% in literature.6,7 In terms of the segment of the gastrointestinal tract involved, the majority of AEF (87%) occurs between the aorta and the third or fourth portions of the duodenum. Jejunum is involved in 7%, ileum in 4%, and colon in only 2% of the cases.4,8-11 The proximal suture line between the prosthesis and aorta is the most common place in the formation of fistulas. Aortoenteric fistula related to the distal suture line of the prosthesis is rare in the literature.4,6,10 Aortoenteric fistulas are more likely to occur subsequent to operation for ruptured aortic aneurism than after elective aneurysmectomy.20 The incidence is almost insignificant when the graft is placed for aortoiliac occlusive disease.20 The prosthesis material does not seem to influence the incidence of fistula, but the aortic sutures involving silk line used to be more likely related to the disruption of the suture line and the formation of pseudoaneurysms in comparison with more recent suture materials.11,20 Several mechanisms have been proposed for the formation of AEF. The primary event is still obscure and controversial. The presence of the aortic graft is necessary for the development of secondary AEF, but not sufficient.21-24 Two main mechanisms have been related with the pathogenesis of this disease: infection (with inflammatory response) and mechanical disturbances.4,5,20 CURRENT SURGERY • Volume 62/Number 1 • January/February 2005
FIGURE 6. The patient underwent laparotomy with full dissection of the aorta, excision of the entire aortic graft, oversewing of the aortic stump, sigmoidectomy, and end-colostomy (Hartmann’s procedure).
The prosthesis infection is associated with the rupture of the suture line and formation of pseudoaneurysm, which then erodes into the overlying bowel.4,11,20 This may consist in total or partial separation of the nonelastic graft wall and the abdominal aorta. Once the graft is seeded with bacteria, fistulization occurs in 12% to 33% of the cases.25 In the case reported above, fistulization between colon and aorta/iliac artery occurred in the distal suture line, an infrequent observation. Infection, however, is not the only primary event related to the fistula formation. Mechanical factors can also be implicated in its pathogenesis,4,20 with the adherence of the bowel to the graft, formation of dense adhesions, and then mechanical erosion of the bowel by the noncompliant pulsatile graft. Because of this, some authors advocate the importance of anastomosis coverage with peritoneal tissues, such as the greater omentum, in order to prevent bowel adherence to the graft.15,19,26 Some microorganisms isolated in blood cultures of patients are frequently associated with this condition such as Staphylococcus aureus, Bacteroides fragilis, Streptococus faecalis, and many Escherichia coli subtypes. However, there is no correlation between specific bacterial infection of suture line, pseudoaneurysm formation, or severity of the infectious process.25 Since the first AEF reported cases, dated from the last centu51
ry,1 to more recent ones, symptoms related with primary or secondary AEF have not changed.4,20 Clinical presentation involves an infectious or hemorrhagic component, sometimes combined. Manifestations of the septic component are usually fever and malaise, ultimately progressing to shock in unrecognized cases.4 Another frequent manifestation is gastrointestinal bleeding, that will be manifested according to the segment of the bowel involved.20,27 This can lead to hypotension or even to hemorrhagic shock.27 Abdominal pain and anemia may also be present.4,6,20 An aggressive diagnostic evaluation and a high index of suspicion are required for a successful outcome, because it allows early diagnosis and prompt surgical intervention. The primary condition to consider AEF is previous abdominal aortic surgery added to any clinical manifestation listed above. In spite of the low incidence of the disease and different clinical manifestations, accurate preoperative diagnosis is not always easily established, even though there has been some advance in imaging techiniques.28 Endoscopy may be helpful, even though it frequently does not identify the fistula. On the other hand, the absence of other lesions responsible for gastrointestinal bleeding supports the initial diagnosis.12 Endoscopy may reveal the site of bleeding in 80% of those examined.29 As the duodenum is the most common segment of the gastrointestinal tract involved in AEF, esophagogastroduodenoscopy is always recomended.5,8,30 Colonoscopy is rarely useful.12 Computed tomography (CT) scans are the most useful test to diagnose infected AEF.28,30,31 Abdominal CT scans may reveal an aortic prosthesis surrounded by inflammation containing small air pockets, a situation that has been associated with graft infection and fistula formation.18 A recent study showed a sensitivity rate of 83.3% for this imaging technique, with specificity and accuracy rates of 99.7% and 93.7%, respectively.28 Other diagnostic methods such as technetium-99m pertechnetate scanning and labeled-leukocyte scintigraphy can be useful in diagnosis of infected AEF, determination of the extent of disease, and selection of the treatment modality, but experience with them is limited.18,32,33 The sensitivity of magnetic resonance imaging in detection of perigraft infection has not been thoroughly investigated but is probably similar to that of CT.31 Barium contrast studies and aortography generally are not helpful in diagnosing either type of fistula. In true aortoenteric fistula, contrast aortography will not demonstrate a fistula if the communication between the graft and the bowel is not large enough or is temporally occluded by a thrombus.18 Ultrasound is particularly important when clinical presentation is atypical or when general medical conditions are critical. In the case reported above, colonoscopy was very useful for the diagnosis, revealing blood in the rectum, sigmoid stenosis secondary to an extrinsic pulsate compression, and hematic infiltration of the sigmoid wall, indicating the probable ana52
tomic location of the fistula. Computed tomography confirmed AEF and allowed prompt surgical intervention. Once AEF is suspected, immediate surgical intervention is necessary. In those patients who were not managed by urgent laparotomy, mortality rate was 100%.4 The type of surgery will depend on the location, extension, and hemodynamic condition of the patient. Complete aortic graft removal is highly recommended, because any prosthetic material inoculated with bowel organisms is a potential source of persistent infection.18 Attempts have been reported in which the graft was repaired or replaced “in situ.” However, these studies have noted early uniform incidence of enteric contamination of the graft and high mortality rates associated with subsequent sepsis.4 The intestinal defect must also be repaired.18,20 The choice of Hartmann’s procedure in the case reported allowed immediate fistula control with minimum intraperitoneal contamination by avoiding a primary enteric anastomosis. This was crucial to minimize lower limb ischemia and to permit early revascularization. After infection and hemorrhagic sources have been controlled, an aortic stump is created by oversewing the remaining native aorta. Reestablishment of blood flow to the lower extremities is usually accomplished by an axillary-bifemoral bypass. The aortic stump may be covered with omentum, peritoneum, or even a muscle flap to prevent recurrent fistulization.9 Even after successful surgical treatment, perioperative mortality ranges between 25% and 90% and is associated with major complications.34 In the last years, a new and less invasive therapeutic method has been developed and studied for the treatment of AEF: endovascular repair. Although still controversial,35 benefits in terms of bleeding and infection control have been shown in highly selected patients.34 In the setting of gross infection, it may also be considered in high-risk patients as a bridge to more definitive treatment after hemodynamic stabilization.34,36,37 New surgical techniques to prevent or even to treat AEF have been described by many authors, such as the coverage of the anastomosis with a vascular prosthesis tailored ring, but experience with them is limited and more studies are needed.38
CONCLUSION Aortoenteric fistula is a rare but life-threatening complication of abdominal aortic surgery. Diagnosis may be difficult because of its low incidence and diversity in clinical manifestations. Aortoenteric fistula should be considered in any patient with previous abdominal aortic surgery who presents with acute gastrointestinal hemorrhage. Even though the duodenum is the most common segment involved in AEF, large bowel may also be affected and should be considered especially when esophagogastroduodenoscopy is normal. Irrespective of the segment of the bowel involved, immediate surgery is highly recommended.
ACKNOWLEDGMENT The authors acknowledge Marcos Retzer for the illustrations. CURRENT SURGERY • Volume 62/Number 1 • January/February 2005
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