Infected Vascular Anastomosis
An infected vascular anastomosis is a bacterial infection occurring at the surgical connection site between two blood vessels or between a vessel and a synthetic graft, representing one of the most devastating complications of vascular reconstructive surgery with potential for life-threatening outcomes including rupture, hemorrhage, sepsis, and death. 1
Definition and Pathophysiology
An anastomosis is the surgical connection created between two blood vessels or between a vessel and a prosthetic graft material. 1 When this site becomes infected, it represents a specific subset of vascular graft infections (VGI) where the infection localizes to the suture line connecting vascular structures. 1
The infected anastomosis is particularly dangerous because disruption of the infected suture line can lead to:
- Catastrophic rupture with life-threatening hemorrhage 1
- Pseudoaneurysm formation (a blood-filled dilation not contained by true vessel wall) 1
- Septic embolization of infected thrombi 1
- Complete graft failure requiring emergency intervention 1
Mechanism of Infection
Intraoperative bacterial contamination during the surgical procedure is the most common cause of infected vascular anastomoses. 1, 2 The second most common mechanism is spread from a contiguous infection source, such as a surgical wound infection or adjacent abscess. 1
Microbiology
The microbiological landscape has evolved significantly, with coagulase-negative staphylococci (particularly Staphylococcus epidermidis) now being more common than Staphylococcus aureus. 2 However, the specific organisms include:
- Gram-positive cocci account for at least two-thirds of all infections 1, 2
- Coagulase-negative staphylococci are the most frequent isolates 2
- Methicillin-resistant S. aureus (MRSA) infections are increasing 1, 2
- Pseudomonas aeruginosa is the most common gram-negative pathogen, accounting for approximately 10% of cases 1, 2
- Polymicrobial infections are increasingly common 1
Clinical Presentation
Early-Onset Infections (<2 months postoperatively)
Early infections present with dramatic systemic signs:
- Fever and rigors, especially with S. aureus 1
- Leukocytosis and sepsis 1, 2
- Wound erythema and abscess formation 1
- Anastomotic rupture with hemorrhage (potentially life-threatening) 1
- Graft occlusion with distal ischemia 1
Late-Onset Infections (>2 months postoperatively)
Late infections are more indolent with predominantly local findings:
- Painful swelling and erythema at the anastomotic site 1, 2
- Draining sinus tract (the most obvious sign) 1, 2
- Absence of systemic sepsis in many cases 1
Frequency and Risk Factors
The infection rate varies by anatomic location:
- Extracavitary grafts (groin, lower extremities): 1.5-2%, up to 6% in the groin 1, 2
- Intracavitary grafts (abdomen, thorax): 1-5% 1, 2
- Emergency procedures carry the highest risk 1, 2
High-risk patient populations include:
- Diabetes mellitus 1
- Immunocompromised states 1
- Multiple comorbidities 1
- Reoperation or revision surgery 1
Major Complications
The American Heart Association identifies these life-threatening complications of infected anastomoses:
- Sepsis and bacteremic spread to distant sites 1
- Amputation (particularly with peripheral grafts) 1
- Anastomotic disruption with rupture or pseudoaneurysm 1
- Enteric fistulae (occurring in 1-2% of aortic reconstructions) 1
- Death 1
Management Principles
Uncontrolled infection at the anastomosis may require immediate surgery with resection of infected tissue and possible complete dismantling of the vascular access. 3 This represents an absolute indication for urgent intervention, as delay can result in catastrophic outcomes. 3
Cultures obtained from CT- or ultrasound-guided aspiration or intraoperative specimens are essential to guide antimicrobial therapy, as wound swab cultures may only reflect colonization rather than the true causative organism. 1
Critical Pitfall
The most dangerous pitfall is delaying evaluation when an infected anastomosis is suspected. 4 Even small amounts of drainage from an anastomotic site warrant immediate assessment, as progression can be rapid and catastrophic. 3, 4 Attempting to use the access site before proper evaluation is completed can exacerbate the complication and lead to complete access failure or life-threatening hemorrhage. 4