Clinical History
91-year-old male patient. EVAR treatment 3 years before for abdominal aortic aneurysm (AAA). Regular follow-up until March 2014 when the patient presented symptoms of abdominal pain and decreased blood pressure. An emergency CT revealed free fluid collection in the retroperitoneum and a focal rupture of the aortic wall, without endoleaks (Fig. 1 a, b).
Imaging Findings
A careful evaluation of the CT examination revealed a marked angulation of the iliac extension added to the right iliac branch. For this reason we reevaluated two plain films, the first done immediately after EVAR and the second one performed 2 days after emergency CT, which showed the distal migration of the iliac extension with only partial overlapping (Fig. 2 a, b). However, CT was unable to identify an active endoleak. We postulated that the migration of the iliac extension was responsible for an intermittent type 3A endoleak and decided to treat it with deployment of an iliac extension in the "overlapping" zone to cover the leakage. Intraoperative angiography confirmed the "intermittent" type 3A endoleak (Fig. 3). The deployment of the iliac extension was successful, however, the manoeuvre caused further bleeding of the sac (Fig. 4) which did not cause significant blood loss and resolved spontaneuosly (Fig. 5).
Discussion
Intermittent endoleaks are an uncommon entity which was reported only recently by May J and Harris JP [1]. In their paper, they affirm that patients with this condition are usually considered to have endotension, with progressive enlargement of the aortic sac in the absence of any demonstrable endoleak. However, they found that approximately one third of these patients have intermittent or posture-dependent endoleaks. These authors describe manoeuvres during ultrasound examinations that enable these endoleaks to be diagnosed. An awareness of the potential presence of these endoleaks may avoid unnecessary conversion to open repair or late rupture. In this case the accurate evaluation of conventional plain films led to the diagnosis, while CT was able to identify the sac rupture but not the active bleeding. Intraoperative angiography confirmed the hypothesis of intermittent EL and the introduction of the catheter in the right iliac stent-graft and the forced injection of contrast media (Fig. 3) revealed the deceitful EL. Therapy was quite easy (simple deployment of another stent-graft inside the previous one), but the procedure was responsible for a further rebleeding inside the sac with growth in size of the perianeurysmatic collection (Fig. 4a, b), which spontaneously regressed after a couple of months.
We have been unable to find other papers focusing on this "intermittent" endoleak. In this case the intermittent EL was caused by a leakage at the conjunction point between the contra-lateral limb and the distal cuff. We believe that other possible causes of intermittent EL could be type 1b EL due to bad sealing of the distal part of the stent-graft or type 3b EL due to small holes in the graft fabric which increase in size in some particular postures of the patient.
Differential Diagnosis List
Intermittent type 3A endoleak after EVAR
Type 1 endoleak
Type 2 endoleak
Final Diagnosis
Intermittent type 3A endoleak after EVAR
