Aortoenteric
fistula secondary to post-traumatic abdominal aortic pseudoaneurysm
(Portuguese
PDF version)
Marcio
Miyamotto,1 Ricardo César Rocha Moreira,2 Carla
Contin Mottin,3 Maria Carolina Colnaghi3
1.Vascular
and endovascular surgeon, Vascular Surgery Service Prof. Dr. Elias
Abrão, Curitiba, PR, Brazil.
2. PhD, Universidade Federal do Paraná (UFPR). Chief
of the Vascular Surgery Service Prof. Dr. Elias Abrão, Curitiba,
PR, Brazil.
3. Resident physician, Vascular Surgery Service Prof. Dr. Elias
Abrão, Curituba, PR, Brazil.
* This
study was carried out at the Vascular Surgery Service Prof. Dr. Elias
Abrão (Hospital Nossa Senhora das Graças and Hospital
Universitário Cajuru of PUC-PR, Curitiba, PR, Brazil).
Correspondence:
Marcio Miyamotto
Rua Padre Anchieta, 1995/2004
CEP 80730-000 - Curitiba, PR
Brazil
Tel.: +55 (41) 339.2312/244.8787
E-mail: miyamotto@brturbo.com
ABSTRACT
Aortoenteric fistula is a serious complication of aortic aneurysm and its surgical treatment. Primary aortoenteric fistula is uncommon and related to untreated abdominal aortic aneurysm. Post-traumatic aortic pseudoaneurysms are a rare etiology of aortoenteric fistula. The authors report a case of an aortoenteric fistula caused by an aortic pseudoaneurysm.
Key-words:
abdominal aortic aneurysm, false aneurysm, fistula.
Palavras-chave: aneurisma de aorta abdominal, pseudo-aneurisma,
fístula.
J
Vasc Br 2004;3(3):269-72
Aortoenteric fistulas (AEF) are abnormal communications between the aortic lumen and the gastrointestinal tract. They are classified as being primary or secondary. The most common type is secondary AEF, which occurs following aortic reconstruction in 0.5 to 2% of cases.1 Primary AEF is extremely rare and occurs in the absence of previous aortic surgery, usually in association with abdominal aortic aneurysm (AAA). The literature describes only a few cases of primary AEF caused by pseudo-aneurysms.2 The present report describes the case of a patient with an aortoduodenal fistula caused by a post-traumatic pseudo-aneurysm of the abdominal aorta which was not diagnosed at the moment of the trauma.
CASE
REPORT
A 66 year-old
male was referred to us with abdominal pain, fever and sweating. The
patient described intense lumbar pain on the right side lasting for
20 days. The pain had started spontaneously and was treated in an emergency
room with anti-inflammatory medication and anesthetic infiltration.
He subsequently presented liquid diarrhea and vomiting, with partial
improvement following treatment of symptoms and hydration. He also reported
lack of appetite for 20 days, with weight loss (6 kg) and decreased
physical strength. The patient had a history of controlled arterial
hypertension, surgery for resection of a malignant tumor 12 years earlier,
inguinal herniorrhaphy 4 years earlier and exploratory laparotomy following
closed abdominal trauma after an accident that occurred 10 years earlier.
He was also a long time smoker. On physical examination, the patient
was dehydrated ++/4 and pale ++/4. Arterial pressure was 130/70, temperature
37 ºC and heart rate 90 bpm. He presented a painful and palpable pulsatile
mass on the gastric mesentery, with diffuse abdominal resistance in
response to pain.
The relevant laboratory data on admission were: globular
volume 30.4; leukocyte count 15,200; immature neutrophils 20; sedimentation
rate 109 mm; creatinine 1.4; potassium 2.9. Abdominal ultrasound revealed
an aneurysm-like dilation in the distal abdominal aorta with diameters
of 67 mm (width) x 46 mm (height/depth) x 50 mm (transverse) and no
evidence of rupture. Subsequently, an angiographic computed tomography
revealed a hypodense mass located distally surrounding the aorta with
invasion of the inferior vena cava (Figure 1).
 Figure
1 - Angiographic tomography of the aorta.
The possibility of infected pseudo-aneurysm was considered (history of previous trauma and angiographic tomography image). Treatment with wide-spectrum antibiotics (ceftriaxone and metronidazole) was started along with hydration and analgesic measures. Due to the strong suspicion of active intra-abdominal infection, an extra-anatomic bypass was performed before correction of the pseudo-aneurysm.
On the next day, the patient was submitted to an axillobifemoral bypass
procedure with PTFE 8.0 mm under general anesthesia. After hemostasis
and wound closure, the patient was prepared for laparotomy. Xyphopubic
midline access revealed an infra-renal pseudo-aneurysm of the abdominal
aorta proximally involving the common iliac arteries. After grasping
the infra-renal aorta and common iliac arteries, the aneurysm sac was
opened, revealing destruction of the aortic wall and typical features
of a pseudo-aneurysm. We resected many thrombi as well as foul-smelling
necrotic tissue, allowing visualization of the duodenal lumen inside
the pseudo-aneurysm, confirming the diagnosis of AEF (Figures 2 and
3). The pseudo-aneurysm capsule was resected with debridement of the
necrotic tissue, and the duodenum was closed with two layers of vicryl
2.0. A jejunostomy was constructed and the abdominal cavity was drained.
The abdominal artery and iliac arteries were ligated with prolene 3.0
suture and a posterior peritoneal flap was interposed between the ligated
arteries and the intestinal loops.
Figure
2 - Bowel lumen (a) visualized from inside the aneurysm sac (b).
Figure
3 - Duodenum (a) and orifice of the fistula (b).
Proteus
mirabilis growth was observed in the culture of thrombi, and the
same antibiotic scheme was maintained based on the antibiogram. Feeding
was reintroduced through the jejunostomy on the fourth post-operative
day, and orally on the 10th postoperative day. The patient remained
in the hospital for treatment of infection in the operative wound until
the 28th day of antibiotic therapy, when he was released in good general
state with palpable distal pulses confirming graft permeability. The
patient was evaluated as an outpatient six months after the surgery
and remains asymptomatic with no changes on laboratory tests. The graft
is permeable, as shown by eco-Doppler.
DISCUSSION
The abnormal
communication between the aortic lumen and the gastrointestinal tract
was initially described by Sir Astley Cooper in 1829. On that occasion,
Sir Cooper described a primary AEF connecting the infra-renal abdominal
aorta and the duodenum.3 Before the appearance
of antibiotics, most primary AEFs were associated with infectious diseases
such as syphilis, tuberculosis and mycotic aneurysms. Currently, most
are related to degenerative or unspecific aneurysms (usually recognized
as atherosclerotic).4 Post-traumatic aneurysms
of the abdominal aorta are a rare cause of primary AEF. About 250 cases
of primary AEF have been described in the world literature, and only
three were associated with pseudo-aneurysms of the aorta. The three
patients described were young and had a history of abdominal trauma.2
Pulsation of the aneurysm or pseudo-aneurysm against the relatively
stable portion of the duodenum leads to repetitive trauma of the intestinal
wall on the anterior aortic wall. As a consequence, there is duodenal
ischemia and necrosis with contamination of the aneurysm wall by gastrointestinal
contents, leading to AEF formation.5 In
the present case, due to the great number of thrombi that is usually
found inside a pseudo-aneurysm, there was no digestive hemorrhage. However,
the contact with gastrointestinal contents resulted in an infectious
process causing abdominal pain, fever, loss of physical strength and
changes in laboratory tests. This evidence supported the initial suspicion
of infected pseudo-aneurysm.
The diversity in clinical presentation makes the diagnosis of primary
AEF extremely difficult. The characteristic triad of abdominal pain,
gastrointestinal hemorrhage and pulsatile abdominal mass, although highly
suggestive of AEF, occurs in only 23% of the cases.5
A literature review of 118 cases of primary AEF revealed that abdominal
pain was present in 32%, palpable abdominal mass in 25% and digestive
hemorrhage in 64% of the cases.6 Among the
complementary tests, computed tomography is among the most useful to
diagnose AEF. The most specific radiological finding is the presence
of gas in the periaortic region in the absence of previous aortic surgery.
Arteriography may be used, but it frequently fails to show the fistulous
tract in the presence of thrombosis. Upper digestive endoscopy performed
by an experienced endoscopist is the first test required if AEF is suspected,
covering all duodenal portions. Upper digestive endoscopy is useful
both to identify the existence of a fistula and, more commonly, to rule
out other sources of bleeding, such as peptic ulcer, which is three
times more prevalent in patients with AAA than in the general population.
However, the identification of another source of bleeding is not enough
to rule out the presence of an AEF.4 Usually,
pre-surgical diagnosis is performed in less than 36% of patients.1
In the review by Sweeney and Gadacz, from 118 patient analyzed, 97 died
before the diagnosis or during surgery, when diagnosis is usually made.6
In the case reported here, the initial diagnostic hypothesis was of
infected pseudo-aneurysm of the abdominal aorta, based on the signs
of infection and on the periaortic mass shown by tomography. For that
reason, we chose to perform an extra-anatomic revascularization using
an axillobifemoral bypass prior to the abdominal surgery. The fistula
became evident only after the pseudo-aneurysm was opened, following
the removal of mural thrombi.
In the presence of an AEF or suspected AEF surgical treatment is the
only choice. In patients with hemodynamic instability, the control of
bleeding is a priority, and the first step is to grasp the aorta. After
identification of the fistula, all the aortic and retroperitoneal tissue
that is no longer viable must be debrided. Reconstruction of the arterial
flow is mandatory in cases of primary AEF, since there is little or
no collateral circulation in patients with AAA. The current trend, according
to O'Brien and Rothstein and many others is in situ reconstruction
using a Dacron prosthesis impregnated with gelatin and rifampicin, primary
repair of the fistula and long-term antibiotic therapy in the absence
of gross contamination of the cavity. According to those authors, the
rate of late complications associated with prosthesis infection is negligible.4,5,7-9
In the cases of extensive contamination, extra-anatomical reconstruction
should be performed after the fistula is repaired. The traditional approach,
with correction of AAA or removal of the infected prosthesis followed
by extra-anatomic reconstruction translates into 36% survival. Some
authors claim that if diagnosis is known or strongly suspected, the
construction of an extra-anatomic bypass with subsequent repair of the
fistula leads to better results, with less morbidity and mortality (56%).1
After primary
duodenal repair, it is advisable to interpose viable tissue between
the aortic stump or Dacron prosthesis and the bowel, to prevent recurrence
of the fistula. Infected tissue samples should be collected for culture
and antibiogram. Specific parenteral antibiotics should be administered
for 4 to 6 weeks followed by oral antibiotics for 6 months.4,7
Despite
being rare, primary AEF is feared by AAA patients. It is associated
with a high mortality rate, and diagnosis is extremely difficult. Thus,
this diagnostic possibility should be considered in all AAA patients
or in the case of a pseudo-aneurysm of the abdominal aorta with atypical
presentation.
REFERENCES
1.
Peck JJ, Eidemiller LR. Aortoenteric fistulas. Arch Surg 1992;127:1191-4.
2.
Taheri SA, Kulaylat MN, Grappa J, et al. Surgical treatment of primary
aortoduodenal fistula. Ann Vasc Surg 1991;5:265-70.
3. Napoli PJ, Meade PC, Adams CW. Primary aortoenteric
fistula from a post-traumatic pseudoaneurysm. J Trauma 1996;41:149-52.
4.Cooper A. The lecture of Sir Astley Cooper on the
principles and practice of surgery with additional notes and cases by
Tyrell F. 5th ed. Philadelphia: Haswell, Barrington and Haswell; 1839.
Apud O'Brien SP, Ernst CB. Aortoenteric fistulae. In: Rutherford
RB. Vascular Surgery. Philadelphia: WB Saunders; 2000. p. 763-775.
5. Rothstein J, Goldstone J. Management of primary aortoenteric
fistula. In: Ernst CB, Stanley JC. Current Therapy in Vascular Surgery.
St Louis: Mosby; 2001. p. 277-279.
6.
Cumpa EA, Stevens R, Hodgson K, Castro F. Primary aortoenteric fistula.
Southern Med J 2002;95:1071-3.
7. Sweeney MS, Gadacz TR. Primary aortoduodenal fistula:
manifestation, diagnosis and treatment. Surgery 1984;96:492-7.
8. O'Brien SP, Ernst CB. Aortoenteric fistulae. In:
Rutherford RB. Vascular Surgery. Philadelphia: WB Saunders; 2000. p.
763-775.
9. Taheri SA, Kulaylat MN, Grappa J, et al. Surgical
treatment of primary aortoduodenal fistula. Ann Vasc Surg 1991;5:265-70.
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