Mycotic or infected aneurysms are focal vascular dilatations from inflammation or infection that results in weakening of the blood vessel wall. It poses a high risk of complications such as aneurysm rupture, uncontrolled sepsis and extensive periaortic infection. Symptoms are frequently minimal during the early stages and a high index of suspicion is essential to make the diagnosis. They are more likely to expand rapidly and rupture without surgical intervention. We report a case of a middle-aged man presented with 3-week history of fever, abdominal pain and low back pain. Initially presented as acute pyelonephritis with subsequent findings of liver abscess, right epididymoorchitis and left infrarenal mycotic aneurysm, which rapidly increased in size and underwent successful endovascular surgery.
A 56-year-old gentleman, presented with a history of fever for 3 weeks, abdominal pain radiating to the right testis and lower back pain also had loss of appetite, nausea and vomiting. A consult to general practitioner was made few days prior to admission and was able to complete course of oral antibiotic, without remarkable improvement.
Systemic review was otherwise unremarkable. Patient is a smoker without other significant past medical history.
On physical examination, patient had temperature of 38.9˚C. Abdominal assessment showed tenderness on the right hypochondriac region and positive right renal punch. Testicular examination was unremarkable. Cardiopulmonary status was normal.
Preliminary investigations showed elevated white cell count of 23.7 × 109 cells/l and Serum ALP 246 U/L. Urine dipstick was positive to nitrite and leukocytes. Urine cytology yielded an acute infective result. Serum sodium of 127 mmol/L and albumin of 27 g/L. Coagulation profile were unremarkable. Initial blood cultures were negative.
Patient was admitted to our hospital with an initial impression of acute pyelonephritis. Given the history of penicillin allergy, IV Ciprofloxacin 400 mg was commenced 12-hourly. However, imaging of kidneys showed no abnormality.
On the second hospital day, patient had persistent fever, abdominal and low back pain, hence, Computed Tomography scan of the Abdomen and Pelvis was ordered which revealed hepatic abscess, and a small saccular aneurysm arising from the left anterolateral aspect of infrarenal abdominal aorta, with surrounding thrombus formation and inflammatory stranding suggestive of Mycotic Aneurysm (
C-reactive protein was 227 mg/dL. Septic screening, including urine and and repeated blood cultures at a different interval, syphilis RPR and HIV test were all negative. Echocardiogram did not establish evidence of Infective Endocarditis. Other investigations conducted include ultrasound of testes, which demonstrated Right epididymo-orchitis, hence Oral Doxycycline was started.
On the fifth day of admission, fever persisted and abdominal pain became intractable. Inflammatory markers such as C-reactive Protein and white cell count continued to rise despite the antibiotics. Computed Tomography Aortogram was done which demonstrated interval increase in size of the saccular infrarenal mycotic aneurysm with more prominent inflammatory changes extending inferiorly to origins of both common iliac arteries and also around the origin of the inferior mesenteric artery (
Immediately referred to vascular surgery and underwent emergency Percutaneous Endovascular Repair (EVAR) with Covered Endovascular Revascularization of Aortic Bifurcation (CERAB) and glue embolisation of the aneurysmal sac.
Bilateral percutaneous incisions were performed on the groin. Sheaths were inserted using guidewire through transfemoral approach. At renal arteries level, aortogram was performed and microcatheter was placed in aneu- rysm sac. Balloon expandable covered stent was deployed just above the bufircation of the abdominal aorta. Another stent was deployed just distal to the most distal renal accessory artery with good overlap between the two aortic stents. Afterwhich, proximal atrium was overinflated with balloon.
Decision was made to perform CERAB procedure, as distal aortic seal was needed and left common iliac dissection occurred post aortic stent deployment. Bilateral common iliac artery kissing stents deployed simultaneously to raise the aortic bifurcation. On aortogram, there was minimal flow in the sac which drained into median sacral artery, hence Lipiodol and glue mixture was used to fill the aneurysm sac through the microcatheter with good result. Prior to closure, aortogram revealed no further flow into the sac and good filling of the iliac arteries. After the procedure, peripheral pulses were palpable. The procedure was uneventful without post-oper- ative complication. White cell count and CRP improved to normal. (Graph 1)
Symptoms of fever, abdominal and back pain disappeared. Repeated imaging of Hepato-Biliary system and Testes showed resolving abscess in the liver and near complete resolution of the right epididymo-orchitis. Patient was discharged after fourteenth hospitalization day with 6 months duration of Ciprofloxacin and 3 months of Metronidazole.
Graph 1.
Four months later, repeated abdominal CT aortogram appeared to have smaller aneurysmal sac without endoleak or para-aortic abscess, whereas the liver abscess showed near complete resoulution. To date there were no documented complications and recurrence of symptoms.
Aneurysms of the infra-renal aorta are by far the most common arterial aneurysms encountered in clinical practice today: they are three to seven times more common than thoracic aneurysms and affect four times as many men as women [
Mycotic aneurysm results from systemic bacteremia and embolization of infectious material, which cause superinfection of a diseased and roughened atherosclerotic plaque acting as a culture media. These emboli usually lodge at the sites of arterial division particularly in the femoral and superior mesenteric arteries. Rarely, organisms may colonize the intact vascular wall through the vasa vasorum, where the arterial wall is weakened by a local suppurative process which results in aneurysm formation [
Risk factors include: 1) Endothelial damage caused by atherosclerosis including pre-existing aneurysm 2) Antecedent infection including bacteremia, which appears to be similar in our case having hepatic abscess 3) Arterial injury including iatrogenic mechanisms, such as percutaneous coronary intervention [
Mycotic aneurysms are defined by the presence of two or more of the following features: sepsis (fever, leukocytosis and pain), positive blood culture, positive culture from the aneurysmal wall, or characteristic radiological appearance (including irregular aortic wall, rapid growth rate, or saccular appearance of the aneurysm). Negative blood cultures and absence of fever does not exclude the diagnosis when the patient has presented with signs of infection and had characteristic radiological findings but had already been commenced on antibiotics [
In Jarrett’s series, only 53% of patients presented with a palpable aneurysm, and less than 50% had aortic calcification. Abdominal pain was present in only 35% of patients. Anderson et al. emphasized that pain, temperature, and fever associated with a pulsatile mass should suggest the diagnosis of mycotic aneurysm. In the series of Mundth et al., pain and fever were present in 94%, with a leukocytosis > 10,000 in 77% of patients and a palpable aneurysm in 65% [
The diagnosis is based upon imaging. CT angiography is the most useful for diagnosing infected aneurysm. MR angiography is an alternative diagnostic study when intravenous contrast is contraindicated. Saccular aneurysm, rapid enlarging of the original aneurysm, and perianeurysm soft tissue mass with or without localized stranded fluid were reported to be typical radiographic manifestations of mycotic aneurysms which appeared to be similar in this case [
Early diagnosis and a combination of surgical intervention and prolonged antibiotic therapy are essential for successful treatment. The choice of antibiotic depends upon the organism grown from blood cultures. However, if no organism is grown then the choice should include a broad-spectrum antibiotic treatment with a combination of ceftriaxone, a fluoroquinolone, and piperacillin-tazobactam [
Prior to the advent of recent less invasive procedure termed endovascular aortic aneurysm repair (EVAR), the gold standard of treatment was wide surgical debridement and in-situ or extra-anatomical repair, however mortality rates of up to 40 per cent are associated with open surgical repair [
It is recognized as an alternative to open surgery with the anticipation that minimally invasive endovascular procedure may reduce the risk of cardiopulmonary, neurological and renal complications in critically ill patients [
Occasionally, EVAR may fail to exclude blood flow from the aneurysmal sac completely, thus may cause endoleak, hence to provide seal on distal aorta, Covered Endovascular Reconstruction of Aortic Bifurcation or CERAB can be performed. Two iliac covered stent-grafts are then placed in this segment, in a “kissing-stent” configuration and inflated. Both stents will make a very tight combination with the aortic stent, as were they moulded together, simulating a new bifurcation. CERAB is safe and feasible and can be performed completely percutaneous. Distal peripheral outflow needs to be sufficient enough be used for the treatment of recurrent or in-stent disease. It is even feasible to treat lesion that extend to the iuxta and/or supral renal aortic region. In a study performed by Peter et al. larger population, longer follow-up, further haemodynamic investigation is needed [
Irene S. Beltran-Ordonez,Tay Seow Yian,Ang Hou,Eric Wong Ming Hai, (2015) Mycotic Aneurysm of Infrarenal Aorta: A Case Report and Review of Literature. Journal of Biosciences and Medicines,03,88-93. doi: 10.4236/jbm.2015.33013