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Textbook/Vascular surgery/Anastomotic pseudoaneurysm
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Anastomotic pseudoaneurysm

Recognise false aneurysm caused by arterial anastomotic disruption, identify rupture, infection and limb-threat features, define the reconstruction with imaging, and select urgent or elective repair without confusing it with a simple puncture-site lesion.

25 min full readUK scopeSources checked 13 Sept 2026Clinical review pending
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Threatened or ruptured anastomosis

Sudden pain, rapid expansion, skin necrosis, external bleeding, hypotension, falling haemoglobin, neurological deficit or acute limb ischaemia around a previous arterial reconstruction suggests impending or established rupture.

Action: Protect the site from pressure or puncture, activate vascular and major-haemorrhage pathways, resuscitate and obtain immediate CTA when physiology permits. Plan proximal and distal control before exploration; use endovascular exclusion for rapid control when anatomically suitable while addressing infection and definitive durability.

Open the sections you need. The overview is shown first.
01OverviewDefinition, clinical context and the essential points that orientate the chapter.

An anastomotic pseudoaneurysm forms when part or all of an arterial suture line loses integrity and blood escapes beyond the native arterial wall but remains contained by soft tissue, scar or graft material. It may occur early from technical failure or infection, or years later from degeneration, ongoing arterial dilatation, mechanical stress and suture or graft fatigue. A true para-anastomotic aneurysm instead represents progressive dilatation of the adjacent native artery. Both can enlarge silently, but false and saccular morphology justifies greater concern because containment is not a normal arterial wall.

Location determines presentation and repair. Femoral lesions may be visible or palpable and can threaten skin, compress vein or nerve, embolise or thrombose the bypass. Aortic lesions are often found during surveillance or present with abdominal or back pain, rupture or fistulation. Infection is the pivotal diagnostic branch: an infected pseudoaneurysm requires cultures, debridement, appropriate reconstruction and antimicrobial therapy, while a sterile degenerative lesion may be excluded with an endograft or repaired openly according to landing zones, branch vessels and physiological reserve.

Key points

  • A painful, rapidly enlarging or skin-threatening mass beside a vascular anastomosis is a rupture emergency: do not compress or aspirate it; obtain urgent vascular control and CTA when the patient can tolerate imaging.
  • In every late para-anastomotic aneurysm, consider infection using history, examination, blood cultures, inflammatory markers and CTA; use deep samples and FDG-PET/CT or labelled-white-cell imaging when uncertainty remains.
  • CTA must define true and false components, proximal and distal landing or clamp zones, graft patency, branch involvement, distal runoff, active bleeding and signs of infection before definitive repair.
  • A pseudoaneurysm is outside the normal arterial wall and contained by surrounding tissue; a true para-anastomotic aneurysm retains all wall layers adjacent to the suture line.
  • There is no validated universal diameter threshold for para-anastomotic pseudoaneurysm repair; symptoms, growth, saccular or false morphology, skin threat, infection and anatomical feasibility determine urgency.
  • Non-infected aorto-iliac para-anastomotic aneurysm is often suitable for endovascular repair, whereas accessible femoral lesions frequently require open repair and reconstruction.
  • Endovascular exclusion controls bleeding and avoids hostile re-entry but can cover branches, compromise access or leave infected material; the repair plan must include surveillance and infection status.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
01

Suture-line degeneration

Late fatigue, calcified native artery, progressive dilatation and mechanical stress can disrupt sutures or adjacent arterial tissue years after reconstruction.

02

Technical early failure

Tension, poor tissue purchase, graft mismatch or an unrecognised operative defect can cause early leakage and contained false aneurysm.

03

Graft infection

Biofilm infection destroys arterial wall and anastomosis, making even a small pseudoaneurysm biologically unstable and prone to rupture.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
  1. 1
    Contained arterial leak

    Blood passes through an anastomotic defect into surrounding scar and soft tissue, which form a sac lacking the normal three-layer arterial wall.

  2. 2
    Expansion and compression

    Systemic arterial pressure enlarges the sac, thins overlying skin and compresses adjacent vein, nerve, graft or ureter.

  3. 3
    Thrombus and embolisation

    Turbulent flow promotes mural thrombus that can embolise distally or propagate into the reconstruction, causing acute or chronic ischaemia.

  4. 4
    Infective disruption

    Microbial inflammation weakens sutures and tissue, producing rapid enlargement, recurrent bleeding, fistulation and failure of prosthetic re-repair.

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

A new enlarging mass, expansile pulsation, bruit, pain, bruising or pressure symptoms near a bypass anastomosis strongly suggests contained arterial leakage.

Threatened skinRed flag

Shiny, thinned, erythematous, ulcerated or bleeding skin over a superficial pseudoaneurysm indicates diminishing containment and impending external rupture.

Infective phenotype

Fever, malaise, recurrent bacteraemia, wound sinus, graft exposure, surrounding inflammation or early failure suggests infection-mediated suture-line destruction.

Distal ischaemiaRed flag

Reduced graft flow, absent pulses, blue toes, rest pain or neurological deficit can arise from mural thrombus, embolisation, kinking or complete graft thrombosis.

Deep aortic presentation

Abdominal, back or groin pain, gastrointestinal bleeding, anaemia or an incidental saccular lesion on surveillance imaging may be the only evidence of aortic anastomotic failure.

Red flags requiring action

  • A rapidly enlarging pulsatile mass, severe pain, bruising, thinning skin or a new sentinel bleed indicates threatened rupture and needs immediate vascular assessment.
  • Fever, wound drainage, bacteraemia, perigraft gas or fluid, or early para-anastomotic failure suggests graft infection rather than sterile degeneration.
  • Coolness, rest pain, sensory or motor loss, absent distal Doppler signals or sudden graft dysfunction indicates thrombosis or distal embolisation with limb threat.
  • Haemodynamic instability, abdominal or back pain, gastrointestinal bleeding or an unexplained fall in haemoglobin after aortic repair suggests concealed rupture or fistulation.
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.

  1. 01
    CT angiography with arterial-phase reconstructionFirst step
    Why
    Define the pseudoaneurysm, active bleeding, graft and branch anatomy, clamp or landing zones, distal perfusion and evidence of infection.
    Interpretation and limitations
    Contrast outside the expected lumen communicating with the anastomosis confirms a false aneurysm; perigraft inflammation, gas, fluid, fistula or rapid tissue change raises infection.
  2. 02
    Blood cultures and infection work-up
    Why
    Determine whether anastomotic failure is caused by vascular graft infection before selecting reconstruction.
    Interpretation and limitations
    Obtain cultures before antibiotics when safe; combine them with clinical and imaging criteria because normal markers or negative cultures do not exclude biofilm infection.
  3. 03
    Duplex ultrasound
    Why
    Characterise accessible femoral or peripheral lesions, flow communication, mural thrombus and distal graft patency.
    Interpretation and limitations
    A communicating neck and swirling flow support pseudoaneurysm, but ultrasound must not delay CTA or operative control when rupture, deep extension or infection is suspected.
  4. 04
    FDG-PET/CT or labelled-white-cell imaging
    Why
    Clarify suspected low-grade graft infection and map its extent when CTA and microbiology are inconclusive.
    Interpretation and limitations
    Focal heterogeneous uptake concordant with graft abnormality is more suspicious than diffuse postoperative inflammation; interpret with timing and structural imaging.
  5. 05
    Distal perfusion assessment
    Why
    Identify thrombosis, embolisation or threatened limb and establish a repair baseline.
    Interpretation and limitations
    Document pulses, Doppler waveforms and ankle or toe pressures when time permits; motor or sensory deficit mandates immediate revascularisation planning rather than prolonged testing.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
01

True adjacent aneurysm

All arterial wall layers dilate beside an intact anastomosis; it may resemble a false aneurysm but has different morphology and natural history.

02

Postoperative seroma

A non-pulsatile perigraft fluid collection can mimic swelling, although duplex shows no arterial communication and infection still requires assessment.

03

Groin haematoma

Recent surgery or anticoagulation may cause a non-flowing collection; delayed expansile pulsation and a communicating neck favour pseudoaneurysm.

04

Lymphocele or hernia

Lymphatic swelling or reducible hernia may occur near a groin incision but lacks arterial flow and threatened haemorrhagic physiology.

07ManagementImmediate care, first-line treatment, alternatives and escalation.
01Emergency pathwayRupture, skin threat or acute ischaemiaFirst stepThe lesion is bleeding, rapidly enlarging, painful with threatened skin, haemodynamically unstable or causing acute limb ischaemia.
  1. 1Protect the lesion, avoid compression or needle puncture, activate senior vascular and anaesthetic support, cross-match blood and resuscitate while maintaining awareness that temporary hypotension may limit uncontrolled bleeding.
  2. 2Obtain immediate CTA if stable enough; otherwise proceed to the fastest method of proximal and distal control, using open exposure, balloon occlusion or endovascular exclusion according to location and resources.
  3. 3Restore distal perfusion and control the defect, while obtaining deep cultures and debriding infected tissue when infection is suspected; do not place an elective closure device into an uncharacterised infected field.
  4. 4Monitor for reperfusion injury, compartment syndrome, renal injury, recurrent bleeding, embolisation and early repair failure.
02Planned pathwayStable non-infected para-anastomotic aneurysmThe patient is stable, imaging shows a contained lesion and a structured infection assessment is negative.
  1. 1Measure morphology and growth, map the entire reconstruction and branch vessels, evaluate cardiac and renal reserve, and discuss rupture uncertainty because no universal size threshold is validated.
  2. 2For aortic or iliac lesions with adequate seal zones, consider endovascular repair preferentially; preserve renal, visceral and internal-iliac perfusion using an appropriate device strategy.
  3. 3Use open repair when anatomy is unsuitable, durable branch reconstruction is required, the lesion is superficial or femoral, or endovascular access and landing zones are inadequate.
  4. 4Establish post-repair imaging to detect endoleak, migration, recurrent pseudoaneurysm, graft occlusion and progression elsewhere.
03Infection pathwayPseudoaneurysm with suspected graft infectionClinical, microbiological or imaging features suggest infection-related anastomotic destruction.
  1. 1Obtain blood cultures and urgent CTA, start sepsis treatment when indicated, and use PET/CT, labelled-white-cell imaging or image-guided deep sampling if this will refine the operative map without unsafe delay.
  2. 2Plan excision of infected graft and devitalised tissue with in-situ or extra-anatomic reconstruction selected for anatomy, organism, contamination and limb or organ perfusion.
  3. 3Use endovascular exclusion as emergency haemorrhage control or a deliberate non-operative strategy only after recognising that it leaves infected material and may require prolonged suppression.
  4. 4Continue culture-directed antimicrobial therapy and long-term surveillance for reinfection, degeneration and new anastomotic failure.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
01

Rupture and exsanguination

Loss of soft-tissue containment produces external, retroperitoneal or intraperitoneal haemorrhage, sometimes after a small sentinel bleed.

02

Acute limb ischaemia

Sac thrombosis, graft occlusion, kinking or distal embolisation can abruptly reduce perfusion and threaten nerve and muscle viability.

03

Skin and wound failure

Pressure causes pain, necrosis, ulceration and graft exposure, converting a contained lesion into external haemorrhage and contamination.

04

Fistulation

Deep aortic lesions may erode into bowel, urinary tract or adjacent structures, causing recurrent infection, bleeding and complex reconstruction.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.
  • During acute care, trend blood pressure, haemoglobin, pain, mass size, skin integrity and distal neurological and Doppler findings.
  • For stable unrepaired lesions, use the same imaging modality and measurement plane where possible, shorten intervals for growth or new symptoms, and give explicit rupture warning signs.
  • After endovascular repair, assess seal zones, endoleak, sac behaviour, branch patency, migration and device integrity according to the procedure-specific programme.
  • After open repair, examine wounds and pulses and maintain long-term cross-sectional surveillance because para-anastomotic and non-contiguous aneurysms occur late.
  • Where infection was suspected or confirmed, monitor cultures, inflammatory trajectory, antimicrobial toxicity, deep collections and recurrent pseudoaneurysm rather than relying on wound appearance.
10Special situationsVariants, exceptions and circumstances that change the usual approach.

Not every para-anastomotic aneurysm is false

Adjacent native artery can dilate as a true aneurysm while suture-line disruption creates a false aneurysm; CTA morphology and operative history distinguish the mechanisms.

Puncture-site rules do not transfer

Ultrasound-guided compression or thrombin injection may suit selected recent iatrogenic femoral puncture pseudoaneurysms, not late graft-anastomotic disruption with infection or rupture risk.

Infection lowers the threshold

A small infected pseudoaneurysm can progress rapidly because the suture line is being destroyed; diameter alone cannot express that biological instability.

Control before exposure

Scarred groins and aortic re-entry can release contained haemorrhage. Proximal and distal control, sometimes remote or endovascular, is secured before dissecting the sac.

Whole-graft imaging matters

The visible mass may be one manifestation of broader graft degeneration, infection or inflow and outflow disease; repair planning must not stop at the pseudoaneurysm neck.

11Common pitfallsFrequent interpretation and management errors.
  1. 01

    Compressing or aspirating a threatened anastomotic pseudoaneurysm can precipitate rupture, thrombosis or infection.

  2. 02

    Applying native fusiform aneurysm diameter thresholds to a false or saccular lesion ignores wall disruption and the absence of validated cut-offs.

  3. 03

    Assuming every late lesion is degenerative without investigating infection risks recurrent failure of a new repair.

  4. 04

    Deploying an endograft without mapping branches, access and seal zones may control the sac while causing organ or limb ischaemia.

  5. 05

    Ending follow-up after successful repair misses late endoleak, recurrent pseudoaneurysm and disease progression elsewhere.

Practice

Two practice questions

Question 1 of 20 correct
Vascular surgeryOriginal SBA

Threatened femoral pseudoaneurysm

Six years after a femorofemoral prosthetic bypass, a patient develops a rapidly enlarging pulsatile groin mass with pain and thinning erythematous skin. What is the safest immediate plan?

Sources and review status3 sources · checked 13 Sept 2026 · clinical review pending
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 13 Sept 2026; clinical approval remains outstanding.

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom