Unilateral Leg Oedema in Association with an Aortocaval Fistula
Article Outline
Abstract
The study considers a case of a patient who presented with scrotal and unilateral leg oedema secondary to an aortocaval fistula (ACF) complicating an abdominal aortic aneurysm (AAA). During the operation, caval blood loss was controlled with digital pressure over the fistula, and direct closure performed using a 3/0 prolene suture. The aneurysm repair was carried out with a woven Dacron® graft. The possibility of an ACF in the presence of AAAs should be considered when examining a patient with intractable unilateral leg oedema. The successful outcome depends on early preoperative recognition, prompt surgical repair and careful attention to intra-operative blood loss.
Keywords: Aortocaval fistula, Abdominal aortic aneurysm (AAA), Leg oedema, Scrotal oedema, Investigations, Management
The common causes of unilateral leg oedema include venous insufficiency, lymphoedema and an acute deep vein thrombosis. It is rarely a manifestation of arterial disease.
We report a case of a patient who presented with scrotal and unilateral leg oedema in association with an abdominal aortic aneurysm (AAA). An aortocaval fistula was identified intra-operatively and treated successfully.
Case Report
A 71-year-old man was admitted with a 10-day history of progressive scrotal and left leg swelling, associated with intermittent colicky abdominal pain. His only co-morbidity was hypertension. On examination, he was haemodynamically stable with a systolic blood pressure of 115
mmHg and a pulse of 90bpm. The most apparent clinical finding was a marked swelling of his left lower limb and scrotum, with a palpable, pulsating abdominal mass. We could neither hear a bruit over the aneurysm nor find any clinical signs of heart failure (Fig. 1).
Figure 1
Patient with gross unilateral leg swelling.
Routine blood investigations were unremarkable, except for a mildly raised D-dimer. A duplex scan showed no evidence of a venous thrombosis. However, there was a compromised non-pulsatile flow through the left common femoral vein and external iliac vein. An incidental finding of an AAA was also noted. The inferior vena cava (IVC) was not examined as the differential diagnosis of a fistula was not appreciated at the time.
A computed tomography (CT) angiogram confirmed a large infra-renal AAA (11cm antero-posterior (AP) diameter), a left common iliac aneurysm (4.8cm) and an ectatic right common iliac artery (2.5cm) (Figure 3, Figure 4). The large AAA appeared to be compressing the IVC, leading to a loss of the normal anatomical space between both the structures. Furthermore, there appeared to be a shiny-white porcelain layer over the AAA's anterior wall, suggesting its inflammatory nature (Fig. 2).
Figure 2
A CT angiogram demonstrating a large aneurysm compressing the inferior vena cava (IVC). There is an obliteration of the normal anatomical space between the IVC and aorta. The shiny-white porcelain layer on the anterior wall suggests the inflammatory nature of the aneurysm.
Figure 3
A CT angiogram demonstrating large left iliac aneurysm and ectatic right aneurysm (axial view).
Figure 4
A coronal view of the CT angiogram demonstrating large AAA along with left common iliac aneurysm.
At laparotomy, an infra-renal inflammatory aneurysm with dense adhesions to both common iliac arteries was found. After proximal and distal control was achieved, the aneurysm sac was opened, demonstrating a 1.5-cm fistula to the IVC over the right posterior aortic wall. Caval blood loss was controlled with digital pressure over the fistula, and direct closure performed using a 3/0 prolene suture. The aneurysm repair was carried out with a woven Dacron® graft.
In total, the patient had received 3l of crystalloids, 1.5l of colloids, 4 units of blood, 4 units of fresh frozen plasma and 1.5l of blood through an intra-operative cell-salvage system. He was transferred to intensive care, where he required further respiratory and inotropic support. He was discharged back to the ward after 4 days. His recovery was complicated, with an antibiotic-associated colitis and a chest infection. The swelling of his left lower limb subsided dramatically, but the scrotal swelling persisted for a further 20 days. He was discharged home 21 days following his operation. Routine review at 6 weeks confirmed a complete resolution of his symptoms. He remains well 6 months later.
Discussion
ACFs occur in 3–6% of ruptured AAAs.1 The case of a ruptured aortic aneurysm that produced an aortocaval fistula was first reported by James Syme in 1831. Lehman in 1935 reported the first attempt to surgically repair an ACF, but this proved unsuccessful. Cooley subsequently reported the first successful repair in 1955.1
ACFs have elusive clinical presentations. Gilling-Smith et al. reported that the classic triad of abdominal/back pain, pulsatile mass and abdominal machinery bruit is present only in 20–50% of cases. Other physical findings associated with an ACF include jugular venous distension, pulmonary oedema, ascites, pulsating varicose veins and lower extremity oedema.1
Venous hypertension distal to the fistula, along with compression of the great veins secondary to the aneurysm, can lead to the clinical manifestations of bilateral swollen cyanosed legs, scrotal oedema, haematuria or haematochezia.2 Similar presentations that occur unilaterally in the lower limb are usually secondary to an iliac arteriovenous fistula.1, 3
Our patient presented with unilateral leg and scrotal swelling without obvious signs of heart failure, lymphoedema or an acute deep vein thrombosis. A bruit was not elicited preoperatively, and this, we postulate, may be secondary to the patient's large body habitus, a thrombus partially occluding the fistula or a low-pressure arteriovenous shunt.
Intra-operatively, the fistula to the IVC was located at the right posterior aortic wall, thus ruling out the more common finding of an iliac arteriovenous fistula as the source of his symptoms. We postulate that the plausible explanation for his unilateral lower limb and scrotal oedema could be the result of two causal factors: (1) external compression from his large left common iliac aneurysm resulting in decreased venous return to the left leg and (2) regional (pelvic) venous hypertension leading to the marked scrotal oedema.
The patient in this case was also found to have an inflammatory AAA (IAAA) characterised by a shiny-white porcelain appearance with thickened anterior and lateral walls and fibrous retroperitoneal extensions leading to adhesions with adjacent structures. IAAAs are recognised to be variants of AAAs. They represent 3–10% of all AAAs and predominantly occur in men.4 Recently, they are recognised not as a single clinical and pathological entity but as an inflammatory variant of the well-known atherosclerotic AAA.4
Preoperative diagnosis of an ACF can be often difficult. A contrast CT angiogram is the most common imaging modality, and there are three pathognomonical findings seen on CT: namely (1) indentation and fistula line in the vena cava, (2) disappearance of fatty planes between the vena cava and aorta and (3) rapid contrast passage into the vena cava.3, 5 Despite this, the diagnosis can be overlooked preoperatively in 50% of cases.6 The attributing factors include an occlusion of the ACF by a mural thrombus and a small ACF size.3, 5, 6 In retrospective review of the CT angiogram (acquired at 0.75-mm slices, reviewed at 3-mm slices), we were still unable to delineate specifically the location of the fistula. However, contrast enhancement of the IVC would have raised the suspicion of an ACF, but this was overlooked at the time.
An ACF in the presence of a ruptured AAA is associated with a high mortality rate of 22–75%.1 The outcome is dependent on appropriate management of perioperative haemodynamics and control of intra-operative bleeding.
The methods of achieving haemostasis intra-operatively include insertion of balloons into the IVC or more commonly by direct digital compression. Closure of the ACF can be achieved by direct suturing, patch repair of the fistula with Dacron®, ligation of the vena cava,7 an aortic exclusion technique or endovascular procedures.8, 9 Although there have been successful attempts to treat an ACF endovascularly, the follow-up interval has been short. Some have voiced concerns in this repair because of the persistent communication between aortic sac and the IVC, which could lead to a high flow type II endoleak.5 We achieved haemostasis and repair of the fistula through direct digital compression and closure with prolene sutures.
In conclusion, ACFs are rare clinical entities and have varied clinical presentations. The possibility of an ACF in the presence of an AAA should be considered when examining a patient with intractable unilateral leg oedema. The successful outcome depends on early preoperative recognition, prompt surgical repair and careful attention to intra-operative blood loss.
Conflict of Interest
None to declare.
References
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PII: S1533-3167(08)00037-X
doi:10.1016/j.ejvsextra.2008.12.003
© 2008 European Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
Refers to article:
- Unilateral Leg Oedema in Association with an Aortocaval Fistula , 16 March 2009
