Prosthetic graft infection

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Vascular graft and endograft infection ranges from an early contaminated wound to late low-grade biofilm infection, abscess, infected pseudoaneurysm or fistulation into bowel, airway, urinary tract or skin. Presentation varies by graft location. Peripheral infection often produces groin pain, erythema, mass, sinus or exposed graft. Aortic and thoracic infections may be hidden, presenting with fever, malaise, back pain, recurrent bacteraemia or a sentinel bleed. The catastrophic transition is anastomotic destruction with rupture, haemorrhage, distal embolisation or acute graft occlusion.

Diagnosis is deliberately composite because no single test is definitive in every patient. The MAGIC criteria group clinical or surgical, radiological and laboratory or microbiological evidence. Blood cultures may identify haematogenous or systemic infection, while deep perigraft samples are more reliable than superficial wound swabs. CTA defines perigraft gas or fluid, abscess, pseudoaneurysm, graft disruption and fistulation. Early postoperative changes can mimic infection and low-grade infection may be subtle, so FDG-PET/CT or labelled-white-cell imaging is used selectively to clarify metabolic activity and map extent.

Key points

In a patient with vascular prosthetic material and unexplained sepsis, pain, bacteraemia or bleeding, obtain blood cultures and urgent CTA; involve a specialist vascular team early and do not wait for superficial wound changes.
Active bleeding or anastomotic disruption requires resuscitation and proximal control; endovascular stent-grafting may bridge an unstable patient to definitive graft excision, reconstruction and repair of an enteric or bronchial defect.
Whenever feasible, obtain multiple deep perigraft or explanted-graft specimens before antibiotics; avoid relying on superficial swabs, but never delay empirical broad-spectrum treatment in severe sepsis or shock.
Use the MAGIC framework: graft infection is suspected from one major or two minor criteria from different categories and diagnosed by one major plus another criterion from a separate category.
CTA is the initial anatomical study; FDG-PET/CT or labelled-white-cell SPECT/CT can strengthen low-grade diagnosis or map extent when CTA alone is uncertain.
Definitive therapy usually combines excision of infected graft and devitalised tissue, restoration of flow when required, viable-tissue coverage and culture-directed antimicrobial therapy.
Antimicrobial selection and duration depend on organism, graft removal, reconstruction and residual infection; incomplete removal or high-risk organisms may require prolonged or lifelong suppression after specialist review.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Peri-operative contamination

Skin organisms, groin contamination, prolonged operation, emergency re-intervention, wound breakdown or adjacent infected tissue can seed prosthetic material at implantation.

Late haematogenous seeding

Bacteraemia from another site can colonise graft biofilm years later, particularly with virulent organisms or compromised tissue coverage.

Fistulation and erosion

Mechanical contact, anastomotic degeneration or infection can erode graft into bowel, airway or urinary tract, creating recurrent contamination and haemorrhage.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Biofilm persistence
Adherent organisms produce extracellular matrix on prosthetic surfaces, limiting antimicrobial penetration and phagocytosis and sustaining relapse despite transient bloodstream clearance.
2
Tissue destruction
Inflammation and proteolysis weaken arterial wall and suture lines, producing pseudoaneurysm, disruption, rupture, thrombosis or septic embolisation.
3
Contiguous spread
Perigraft infection extends into soft tissue, vertebrae or adjacent viscera; an enteric or bronchial communication continually re-inoculates the graft bed.
4
Reconstruction risk
Removing infected material can interrupt critical perfusion, while new conduit in a contaminated field risks thrombosis or reinfection; viable-tissue coverage improves separation and healing.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Early wound infection

Within months of implantation, fever, wound breakdown, purulent discharge, groin erythema, exposed graft or deep collection suggests operative contamination extending to prosthetic material.

Late indolent infection

Malaise, weight loss, recurrent low-grade fever, unexplained bacteraemia, back pain or persistently raised inflammatory markers may be the only clues years after surgery.

Infected pseudoaneurysmRed flag

A painful or pulsatile mass, new bruit, rapid enlargement, skin compromise, sentinel bleeding or acute limb ischaemia suggests infection-related anastomotic failure.

Graft-enteric fistulaRed flag

Haematemesis, melaena, sepsis or abdominal pain after aortic grafting may reflect enteric erosion; a small herald bleed can precede fatal haemorrhage.

Thoracic fistulation

Haemoptysis, recurrent chest infection, sepsis or thoracic pain after aortic graft or endograft placement raises aorto-bronchial or aorto-oesophageal fistulation.

Red flags requiring action

A small self-limiting haematemesis or melaena in a patient with an aortic graft may be a herald bleed from graft-enteric fistulation.
Haemoptysis after thoracic aortic grafting can indicate an aorto-bronchial fistula and may precede catastrophic airway haemorrhage.
Groin bleeding, a pulsatile infected mass, acute limb ischaemia or sudden severe pain suggests anastomotic disruption or infected pseudoaneurysm.
Persistent fever, bacteraemia, back pain, weight loss or raised inflammatory markers with no source warrants graft-focused imaging even years after implantation.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Blood cultures and urgent CT angiographyFirst step
Why
Identify systemic infection and define graft integrity, collections, pseudoaneurysm, active bleeding, fistulation and distal perfusion.
Interpretation and limitations
Perigraft gas or fluid beyond the expected postoperative interval, increasing collections, soft-tissue inflammation, pseudoaneurysm or contrast extravasation supports infection; a negative scan does not reliably exclude low-grade disease.
02
Deep microbiological sampling
Why
Identify causative organisms and susceptibility while avoiding misleading surface colonisers.
Interpretation and limitations
Send multiple image-guided perigraft aspirates or operative tissue and graft specimens using agreed microbiology handling; superficial sinus swabs and accidental needle passage through bowel are inadequate.
03
FDG-PET/CT
Why
Improve detection and map extent when low-grade infection is suspected or CTA is equivocal.
Interpretation and limitations
Focal, heterogeneous uptake aligned with graft abnormalities is more concerning than diffuse early postoperative uptake; interpret timing, pattern and CT findings together.
04
Labelled-white-cell scintigraphy with SPECT/CT
Why
Provide highly specific functional localisation where available.
Interpretation and limitations
Increasing or spatially concordant uptake supports active infection; the test is time-consuming and availability limits emergency use.
05
Endoscopy or organ-specific assessment
Why
Evaluate suspected graft-enteric, aorto-oesophageal, bronchial or urinary fistulation and plan adjacent-organ repair.
Interpretation and limitations
A negative endoscopy does not exclude a graft-enteric fistula; avoid diagnostic delay in an unstable bleeding patient and coordinate with vascular imaging.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Expected postoperative change

Early perigraft fluid, gas and inflammatory uptake can be physiological; serial change, postoperative timing and concordant clinical or microbiological evidence distinguish infection.

Sterile graft reaction

Inflammatory response to graft material can cause fluid or uptake without viable organisms, but progressive collections, focal uptake or anastomotic change favour infection.

Native arterial infection

Infective aortitis or mycotic aneurysm can mimic graft infection but originates in native arterial tissue and changes the reconstruction map.

Malignancy or spinal infection

Weight loss and back pain may reflect cancer, discitis or vertebral osteomyelitis; cross-sectional and metabolic imaging should define their relation to the graft.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Emergency pathwayBleeding, rupture or septic shockFirst stepThere is active bleeding, haemodynamic instability, anastomotic disruption, acute graft occlusion or uncontrolled sepsis.

1Resuscitate, activate massive-haemorrhage or sepsis pathways as indicated, obtain blood cultures when this causes no delay, start broad-spectrum intravenous antimicrobial therapy and arrange immediate specialist transfer.
2DefinitiveSecure proximal and distal arterial control before definitive exploration; an occlusion balloon or endograft may rapidly control bleeding when open exposure is unsafe or delayed.
3DefinitiveTreat endovascular control as a bridge when infected tissue, fistulation or residual prosthetic material still requires definitive management; involve gastrointestinal, thoracic or urological surgeons for the affected organ.
4After stabilisation, define reconstruction, tissue coverage, antimicrobial course, organ support and surveillance for recurrent infection or repair failure.

02Definitive pathwayHaemodynamically stable confirmed graft infectionDefinitiveClinical, imaging and microbiological evidence supports infection without immediate rupture or shock.

1Map the full graft, anastomoses, abscess, fistulae, distal runoff and patient operative risk; obtain deep microbiology and convene vascular, radiology, microbiology or infection and relevant organ specialists.
2Excise infected prosthetic material and devitalised tissue when feasible, deciding between in-situ and extra-anatomic reconstruction according to anatomy, organism, contamination and limb or organ perfusion needs.
3AlternativePrefer autologous or biological material where appropriate; alternative infection-resistant prostheses may be selected when vein or allograft is unsuitable or unavailable.
4Cover the reconstruction with viable tissue when possible and tailor antimicrobial duration to organism, completeness of removal, new conduit and residual infected field.

03Exceptional pathwayPatient unsuitable for definitive graft excisionDefinitivePhysiology, anatomy or goals of care make definitive operative source control disproportionate or impossible.

1Confirm that the decision follows specialist multidisciplinary assessment and informed discussion of persistent infection, bleeding, rupture, embolisation and recurrent sepsis risks.
2Drain accessible collections and control bleeding endovascularly when beneficial, recognising that retained infected material prevents reliable eradication.
3Use culture-directed prolonged or suppressive antimicrobial therapy with explicit toxicity, resistance and failure monitoring.
4EscalationDefine escalation limits, symptom control, imaging strategy and rapid reassessment triggers rather than implying that antibiotics alone are curative.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Catastrophic haemorrhage

Anastomotic rupture or graft-enteric, aorto-oesophageal or aorto-bronchial fistulation can cause a herald bleed followed by exsanguination.

Septic embolisation

Infected thrombus or graft debris can embolise distally, producing acute limb ischaemia, visceral infarction, stroke or metastatic abscess.

Graft occlusion

Inflammation, thrombosis or reconstruction failure may abruptly compromise limb or organ perfusion and necessitate urgent revascularisation.

Recurrent infection

Retained prosthesis, incomplete debridement, resistant organisms, ongoing fistulation or poor tissue coverage increase relapse, chronic sinus and suppressive-therapy dependence.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Trend haemodynamics, lactate, organ function, haemoglobin and bleeding during acute presentations; recurrent small bleeds require the same urgency as major haemorrhage.
Repeat blood cultures to document clearance and investigate persistent bacteraemia for endocarditis, septic emboli or uncontrolled perigraft infection.
Monitor renal function when repeated contrast imaging and nephrotoxic antimicrobial combinations are considered; adapt imaging and therapy without losing anatomical oversight.
After reconstruction, assess wounds, limb or organ perfusion, graft patency and inflammatory trajectory, and image promptly for new pain, fever, bleeding or pseudoaneurysm.
Long-term follow-up is required after incomplete excision, infection-resistant prosthetic replacement or allograft reconstruction because reinfection, degeneration, thrombosis and anastomotic failure may be delayed.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Biofilm changes treatment expectations

Organisms embedded on prosthetic material are less accessible to host defence and antimicrobials. Apparent clinical improvement without source control can therefore precede relapse.

Postoperative gas has a clock

Gas or fluid may be expected early after surgery but becomes increasingly suspicious when persistent, increasing or accompanied by inflammatory change, positive microbiology or pseudoaneurysm.

A herald bleed is an emergency

Temporary cessation of gastrointestinal or airway bleeding reflects transient thrombus or pressure change, not healing; definitive rupture can follow unpredictably.

Endovascular control is not debridement

A stent graft can arrest life-threatening haemorrhage rapidly but may add prosthetic material to an infected field and does not repair bowel or bronchial contamination.

Revascularisation depends on the original indication

After infected peripheral graft removal, a claudicant may tolerate delayed reconstruction, whereas severe ischaemia or threatened tissue usually requires immediate restoration of flow.

11Common pitfallsFrequent interpretation and management errors.

01
Excluding deep graft infection because the incision is healed misses the common late, indolent presentation.
02
Treating a superficial swab as definitive microbiology confuses colonisation with organisms within the graft bed.
03
Using a normal or equivocal CTA alone to dismiss low-grade infection ignores the role of PET/CT or labelled-white-cell imaging.
04
Calling endovascular haemorrhage control definitive without an infection plan leaves the source, fistula and recurrent-bleeding risk unaddressed.
05
Starting prolonged antibiotics before obtaining feasible cultures may sterilise samples and prevent rational narrowing, although unstable sepsis must never wait.

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