Aortoenteric fistulaMANAGEMENT

GASTROINTESTINAL PRESENTATIONS · 12 SECTIONS

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657 items

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01Approach to the Critical Patient/attcp66

Recognition and the herald bleed

›Aortoenteric fistula is exsanguinating gastrointestinal hemorrhage until excluded

›Any gastrointestinal bleeding in a patient with an aortic graft or known abdominal aortic aneurysm is aortoenteric fistula until proven otherwise

›Secondary fistula after aortic graft surgery is the common scenario; onset ranges from weeks to more than 15 years after repair

›Primary fistula arises from an untreated aneurysm, mycotic aneurysm, tumor, radiation, or an ingested foreign body

›Herald bleed is the warning shot

›A self-limited episode of hematemesis or melena precedes catastrophic hemorrhage by hours to weeks

›Bleeding stops transiently as hypotension and clot seal the fistula, then recurs without warning

›A stabilized herald bleed still mandates admission, vascular surgery, and a definitive operative plan

›The classic triad is unreliable

›Gastrointestinal bleeding, abdominal or back pain, and a pulsatile abdominal mass together appear in roughly 10 percent

›Absence of a pulsatile mass does not lower suspicion, particularly after graft repair

›Fever or unexplained bacteremia in a graft patient may be the only clue to graft-enteric erosion

Immediate resuscitation actions

›Vascular access and blood

›Two large-bore peripheral catheters, 14 to 16 gauge, or a rapid-infusion catheter

›Central venous or intraosseous access if peripheral attempts fail

›Send type and crossmatch for 6 units of packed red cells immediately

›Transfuse group O until type-specific blood is ready, O-negative for people of childbearing potential

›Activate the massive transfusion protocol

›Activate on clinical suspicion, not after hemodynamic collapse

›Deliver packed red cells, plasma, and platelets in a 1:1:1 ratio

›Minimize crystalloid to avoid dilutional coagulopathy and clot disruption

›Balanced, hypotensive resuscitation

›Target systolic pressure 80 to 90 mmHg, mean arterial pressure about 65 mmHg, a palpable radial pulse, and preserved mentation until hemorrhage is controlled

›Do not resuscitate to a normal blood pressure before surgical control; this dislodges clot and accelerates bleeding

›Higher targets apply in specific groups (see exceptions below)

›Pharmacologic hemostatic support

›Tranexamic acid 1 g IV over 10 minutes, then 1 g IV infused over 8 hours, when hemorrhage is ongoing

›Reverse anticoagulants and correct coagulopathy in parallel

›Keep ionized calcium above 1.1 mmol/l during transfusion

›Mobilize definitive care

›Emergent vascular surgery consultation

›Alert the operating room, interventional radiology, anesthesia, and blood bank

›Broad-spectrum antibiotics with antifungal cover after blood cultures are drawn

›Supportive measures

›Nil by mouth, nasogastric tube, intravenous proton pump inhibitor infusion

›Urinary catheter, arterial line, continuous monitoring

›Active warming with a fluid warmer and forced-air blanket to prevent the lethal triad

Exceptions and hazards during stabilization

›Blood pressure targets that differ by population

›Concomitant traumatic brain injury or suspected intracranial hemorrhage: do not permit hypotension, target systolic at least 110 mmHg

›Longstanding hypertension or known cerebrovascular or renal artery disease: accept mean arterial pressure 75 to 80 mmHg to preserve cerebral and renal perfusion

›Pregnancy beyond 20 weeks: left lateral tilt and a higher maternal pressure to maintain uteroplacental flow

›Heart rate can mislead

›Beta-blocked or pacemaker-dependent patients may not mount a compensatory tachycardia

›A normal heart rate does not exclude significant blood loss

›Trend the shock index (heart rate divided by systolic pressure); a value above 0.9 signals meaningful hemorrhage

›Interventions that can kill this patient

›Intra-aortic balloon pump is contraindicated: it risks aortic disruption, dissection, graft injury, and distal embolization in a diseased or infected aorta

›Fibrinolysis is absolutely contraindicated: revisit any presumptive acute coronary syndrome or pulmonary embolism diagnosis before giving thrombolytics or full-dose anticoagulation

›Aggressive endoscopic manipulation of an adherent duodenal clot can provoke immediate exsanguination; endoscopy proceeds only with the operating room ready

›Over-resuscitation to a normal pressure is itself a lethal intervention here

›Oxygenation target and its exceptions

›Target SpO2 94 to 98 percent

›Chronic obstructive pulmonary disease or other chronic hypercapnia: target 88 to 92 percent

›Do not withhold oxygen, but hyperoxia offers no benefit and is not a substitute for blood

Disposition anchor

›Definitive treatment is operative

›No medical therapy closes an aortoenteric fistula

›Every confirmed or strongly suspected case goes to the operating room or intensive care, never home

›Resuscitation is a bridge to the operating room, not an endpoint

›Transfer without delay when resources are absent

›No vascular surgery, hybrid operating room, interventional radiology, or adequate blood bank on site mandates immediate transfer

›Begin resuscitation and antibiotics before and during transfer

›Communicate the words "herald bleed" and "possible aortoenteric fistula" explicitly to the receiving team

›Periarrest bridging options

›Resuscitative endovascular balloon occlusion of the aorta in zone I, or a resuscitative thoracotomy with aortic cross-clamp, may buy time to the operating room in extremis

›These are temporizing only and require an immediate surgical plan

›Verify institutional protocol and operator competence before attempting

02History/hx36

Vascular history and the index bleeding event

›Prior aortic intervention

›Open abdominal aortic aneurysm repair or aortobifemoral bypass, with year and graft material if known

›Endovascular aneurysm repair or thoracic endograft, with year

›Prior graft infection, groin wound breakdown, or anastomotic pseudoaneurysm

›Known aneurysm without repair

›Documented abdominal or thoracoabdominal aortic aneurysm under surveillance

›Most recent measured diameter and rate of growth

›Prior endoleak or reintervention

›Character of the current bleed

›Hematemesis or coffee-ground emesis, estimated volume and number of episodes

›Melena or hematochezia, onset and frequency

›A preceding smaller self-limited bleed days to weeks earlier (herald bleed)

›Associated symptoms

›Abdominal, epigastric, flank, or back pain and its relation to the bleed

›Syncope or presyncope

›Fever, rigors, night sweats, malaise, or weight loss suggesting graft infection

Comorbidities, exposures, and medications

›Infective risk factors

›Prior Salmonella, tuberculosis, or syphilis

›Injection drug use, infective endocarditis, or recent documented bacteremia

›Recent aortic or spinal instrumentation

›Structural and neoplastic risk

›Connective tissue disorder: Marfan syndrome, vascular Ehlers-Danlos syndrome, Loeys-Dietz syndrome

›Abdominal or retroperitoneal malignancy, or prior radiotherapy to the abdomen

›Ingested foreign body or caustic ingestion, especially a button battery or sharp object in a child

›Bleeding-relevant medications

›Anticoagulant class, specific agent, indication, and time of last dose

03Physical Exam/exam37

Hemodynamic status and general appearance

›Vital signs and derived indices

›Heart rate, blood pressure, and postural change in both

›Shock index above 0.9 as a marker of significant hemorrhage

›Respiratory rate, SpO2, and temperature

›Perfusion

›Skin colour and temperature, capillary refill beyond 2 seconds, mottling

›Mental status, with agitation or confusion from hypoperfusion

›Urine output once catheterized

›Evidence of active bleeding

›Blood or coffee-ground material in the nasogastric aspirate

›Melena or frank blood on rectal examination

›Conjunctival and palmar pallor

Abdominal and vascular examination

›Abdomen

›Pulsatile epigastric or periumbilical mass

›Tenderness, guarding, distension

›Audible abdominal bruit

›Midline laparotomy scar

›Groins and peripheral vessels

›Femoral anastomotic pseudoaneurysm as a pulsatile groin mass

›Groin sinus or chronically draining wound suggesting graft infection

›Femoral, popliteal, and pedal pulses and any asymmetry

›Distal embolic signs

›Blue toe, focal digital ischemia, livedo reticularis

›New foot pain with preserved proximal pulses

›Tender, indurated calf muscle from ischemia

04Differential Diagnosis/ddx52

Aortic and graft-related causes

›Aortoenteric fistula

›Graft-enteric fistula with communication to the suture line, producing massive hemorrhage

›Graft-enteric erosion into the bowel lumen without suture-line communication, producing lower-grade recurrent bleeding and sepsis

›Primary aortoenteric fistula from an untreated or mycotic aneurysm

›Ruptured abdominal aortic aneurysm without fistula

›Retroperitoneal hemorrhage with back or flank pain and hypotension

›May coexist with a fistula

›Grey Turner or Cullen sign is late and insensitive

›Anastomotic pseudoaneurysm without fistula

›Pulsatile groin or abdominal mass that may embolize distally

›Can be a precursor to fistula formation

›Detected on cross-sectional imaging or duplex

›Aortic graft infection without fistula

›Fever, elevated inflammatory markers, perigraft fluid or gas on imaging

›Bacteremia with a graft-adherent organism

›May progress to erosion or fistula

›Aortocaval fistula

›Communication into the inferior vena cava rather than bowel

›High-output cardiac failure, a machinery abdominal bruit, leg edema, hematuria

›Not a cause of gastrointestinal bleeding but shares the pulsatile abdomen

Other upper gastrointestinal bleeding sources

›Peptic ulcer disease

›The single most common cause of upper gastrointestinal bleeding overall

›Nonsteroidal anti-inflammatory drug or Helicobacter pylori association

›Does not exclude a concurrent fistula in an at-risk patient

›Esophagogastric varices

›Portal hypertension from cirrhosis or portal vein thrombosis

05Laboratory Tests/lt32

Hematology and coagulation

›Complete blood count

›Baseline hemoglobin, then serial values every 2 to 4 hours during active bleeding

›A normal initial hemoglobin does not exclude major hemorrhage before hemodilution occurs

›Platelet count, with a target above 50 x10^9/l during active bleeding

›Transfusion preparation

›Type and screen plus crossmatch for at least 6 units of packed red cells

›Keep two units ahead of losses and re-crossmatch as the sample ages

›Group and save on any at-risk patient even if not yet bleeding

›Coagulation studies

›Prothrombin time with international normalized ratio and activated partial thromboplastin time

›Fibrinogen, with replacement if below 1.5 g/l, or below 2 g/l in pregnancy

›Viscoelastic testing (thromboelastography or rotational thromboelastometry) to guide component therapy where available

›Anticoagulant quantification

›Anti-factor Xa activity for low molecular weight heparin or direct factor Xa inhibitors

›Dilute thrombin time or ecarin clotting time for dabigatran where available

›Disseminated intravascular coagulation panel including D-dimer if sepsis coexists

Chemistry, infection, and metabolic testing

›Renal function and bleeding markers

›Urea and creatinine, both as a baseline before contrast and because a raised urea to creatinine ratio supports an upper gastrointestinal source

›Electrolytes including potassium

›Ionized calcium and magnesium, rechecked every 30 to 60 minutes during massive transfusion

›Perfusion and gas exchange

›Venous or arterial blood gas

›Serial lactate; a normal early value does not exclude shock

›Point-of-care glucose in any lethargic or poorly responsive patient

›Infection workup

›Two sets of blood cultures before antibiotics; cultures may be negative despite an infected graft

06Diagnostic Tests/dt70

Scoring Systems

›Upper gastrointestinal bleeding risk scores

›Glasgow-Blatchford score stratifies need for intervention; a low score must not reassure when aortoenteric fistula is possible

›Rockall score, pre-endoscopy and full, estimates rebleeding and mortality

›AIMS65 uses albumin, international normalized ratio, mental status, systolic pressure, and age above 65

›Shock and transfusion indices

›Shock index above 0.9, and the modified shock index, flag occult hypoperfusion

›The ABC score and shock index help trigger massive transfusion activation

›None of these scores has been validated to include or exclude aortoenteric fistula

›Aortic graft infection criteria

›The Management of Aortic Graft Infection Collaboration case definition combines clinical or surgical, radiologic, and laboratory criteria

›It supports the diagnosis of graft infection, which frequently coexists with secondary fistula

›Do not force a numeric cutoff the criteria do not define

›Protocol

›Computed tomography angiography of the abdomen and pelvis is the first-line test in a patient stable enough to scan

›Include a non-contrast phase for ectopic perigraft gas and hyperdense clot, then arterial and delayed venous phases

›Oral contrast is generally unnecessary and delays the study

›Findings that support the diagnosis

›Active contrast extravasation from aorta or graft into the bowel lumen

›Ectopic gas around the graft beyond 3 to 5 weeks after implantation

›Loss of the fat plane between aorta and duodenum, focal bowel wall thickening, tethering of bowel to the graft

›Perigraft fluid or soft tissue, pseudoaneurysm, or focal aortic wall disruption

›Interpretation traps

›Perigraft gas and fluid are normal in the first weeks after surgery

›A negative study does not exclude the diagnosis; sensitivity is imperfect and bleeding is intermittent

›With high clinical suspicion, proceed to endoscopy or the operating room despite a normal scan

›Contrast considerations

›Do not withhold iodinated contrast for borderline renal function when the diagnosis is life-threatening

›Send a baseline creatinine but do not wait for it in the unstable patient

›Arrange post-contrast renal monitoring and volume management

MRI

›Role

›Magnetic resonance imaging is not for the unstable patient and is rarely used acutely

›It characterizes perigraft soft tissue and vertebral involvement better than computed tomography when infection is indolent

›It is an adjunct when computed tomography is equivocal and the patient is stable

›Technique and cautions

›Contrast-enhanced sequences improve detection of perigraft inflammation

›Use macrocyclic gadolinium agents and weigh nephrogenic systemic fibrosis risk in advanced renal failure

›Scan time and monitoring limitations make it unsuitable during active hemorrhage

›Alternatives for occult graft infection

›Radiolabeled white cell scintigraphy

›Fluorodeoxyglucose positron emission tomography combined with computed tomography

›These support infection but do not localize a fistula

Ultrasound

›Bedside resuscitation ultrasound

›Inferior vena cava calibre and cardiac contractility to guide transfusion

›Focused assessment for free intraperitoneal fluid; retroperitoneal blood is poorly seen

›Lung views for transfusion-associated circulatory overload

›Vascular applications

›Measurement of a native aneurysm sac

›Groin duplex for a femoral anastomotic pseudoaneurysm

›Limited by bowel gas for direct visualization of the fistula

›Limitations

›Ultrasound cannot exclude aortoenteric fistula

›Operator dependence and body habitus reduce sensitivity

›A normal scan must not delay definitive imaging or surgical consultation

Endoscopy and angiography

›Upper endoscopy

›Perform with intent to reach and inspect the third and fourth portions of the duodenum

›Suggestive findings are visible graft material, an adherent non-bleeding clot, a pulsatile submucosal mass, or blood from the distal duodenum without a mucosal lesion

›Do not disturb an adherent clot; keep the operating room on standby during the procedure

›Sensitivity for the fistula itself is low; a main value is excluding other sources

›Lower endoscopy

›Colonoscopy or flexible sigmoidoscopy if a colonic fistula or ischemic colitis is suspected

›Bowel preparation is often impractical during active bleeding

›Limited yield in brisk hemorrhage

›Catheter angiography

›Computed tomography angiography is preferred first; catheter angiography is frequently negative because bleeding is intermittent

›It can be therapeutic as a bridge, allowing covered stent placement to control hemorrhage before definitive surgery

›It requires an available interventional suite and does not treat the infection

›Nuclear medicine

›Tagged red cell scintigraphy detects bleeding rates as low as 0.1 to 0.5 ml per minute

›It rarely changes management and delays definitive care

›Reserve it for occult, slow, recurrent bleeding when other tests are unrevealing

07Disposition/dispo24

Admission, consultation, and level of care

›Universal admission

›Every confirmed or strongly suspected aortoenteric fistula is admitted; discharge is never appropriate

›A stabilized herald bleed is admitted to a monitored or intensive care bed with an operative plan

›Keep the patient nil by mouth and consented for theatre

›Consults to mobilize early

›Vascular surgery as the primary service

›General surgery for bowel repair and gastroenterology for endoscopy

›Interventional radiology, anesthesia and critical care, infectious diseases, and the blood bank

›Monitoring while awaiting theatre

›Continuous electrocardiography, an arterial line, hourly urine output

›Serial hemoglobin every 2 to 4 hours and a current crossmatch maintained

›Ionized calcium, potassium, lactate, and temperature on a fixed schedule during transfusion

Transfer criteria and pre-transfer priorities

›When to transfer

›No on-site vascular surgery, hybrid operating room, or interventional radiology

›Inadequate blood bank inventory for massive transfusion

›No intensive care capacity for postoperative management

›Stabilize but do not delay

›Two units of blood available for transport and an agreed massive transfusion pathway with the receiving centre

›Antibiotics given before departure

›Do not wait for endoscopy or complete imaging if it delays transfer

›Communication

›State explicitly "possible aortoenteric fistula" and "herald bleed" to the receiving vascular team

›Send all imaging and the full medication and anticoagulation history

›Use the highest-acuity transport with blood administration capability

08Treatment/t176

Balanced resuscitation, hemorrhage control, and circulatory support

›Resuscitation strategy

›Packed red cells, plasma, and platelets in a 1:1:1 ratio through a rapid infuser with an inline warmer

›Restrict crystalloid to a carrier volume; large boluses cause dilutional coagulopathy, acidosis, and clot disruption

›Permissive hypotension with systolic 80 to 90 mmHg and preserved mentation until surgical control

›Endpoints and their exceptions

›Titrate to a palpable radial pulse, mentation, and a falling lactate rather than to a normal blood pressure

›Traumatic brain injury or suspected intracranial bleed: abandon permissive hypotension, target systolic at least 110 mmHg

›Chronic hypertension, cerebrovascular disease, or dialysis dependence: accept mean arterial pressure 75 to 80 mmHg

›Pregnancy beyond 20 weeks: left lateral tilt and a higher target for uteroplacental perfusion

›Prevent the lethal triad

›Active warming: fluid warmer, forced-air blanket, warm room, target core temperature above 36 degrees Celsius

›Correct acidosis by restoring perfusion, not by routine sodium bicarbonate 1 mmol/kg IV

›Treat ionized hypocalcemia promptly to protect coagulation and contractility

›Monitoring cadence

›Blood pressure every 5 minutes, then continuously once an arterial line is placed

›Hemoglobin, ionized calcium, potassium, fibrinogen, and lactate every 30 to 60 minutes during massive transfusion

›Reassess for transfusion-associated circulatory overload and transfusion-related acute lung injury

›Vasopressor bridge

›Norepinephrine

›Start 0.05 mcg/kg per minute through a central or good-quality peripheral line

›Titrate by 0.02 to 0.05 mcg/kg per minute every 5 minutes toward the permissive mean arterial pressure target

›Reduce increments as the target is approached to avoid overshoot

›Usual ceiling 1 mcg/kg per minute; escalating requirement signals uncontrolled hemorrhage

›Blood and volume come first; vasopressors mask ongoing bleeding and worsen perfusion if used to chase a number

›Wean the infusion as soon as hemorrhage is controlled and volume is restored

›Mechanical circulatory support

›Intra-aortic balloon pump is contraindicated: risk of aortic wall disruption, dissection, graft injury, and distal embolization

›Venoarterial extracorporeal membrane oxygenation is not a hemorrhage-control tool and its anticoagulation requirement is hazardous

›The definitive circulatory intervention is operative vascular control

›Aortic occlusion as a bridge

›Resuscitative endovascular balloon occlusion of the aorta in zone I for the periarrest patient who has a surgical plan

›Track balloon-inflation time and communicate it to the surgical team; distal ischemia accrues quickly

›Open aortic cross-clamp through thoracotomy or laparotomy if endovascular occlusion is unavailable

Blood products and transfusion complications

›Product selection

›Group O red cells until type-specific is available, O-negative for people of childbearing potential

›Thawed plasma and platelets released with each massive transfusion pack

›Cryoprecipitate 10 units or fibrinogen concentrate if fibrinogen is below 1.5 g/l

›Citrate-induced hypocalcemia

›Rapid transfusion chelates calcium; target ionized calcium above 1.1 mmol/l

›Calcium chloride 1 g IV (10 ml of 10 percent) via central access over 5 to 10 minutes, or calcium gluconate 2 to 3 g IV peripherally

›Recheck ionized calcium 10 minutes after replacement and every 30 minutes during ongoing transfusion

›Hyperkalemia and metabolic load

›Older or irradiated units raise serum potassium; follow blood gas potassium

›Treat electrocardiographic hyperkalemia with intravenous calcium, 10 units of soluble insulin with 25 g of dextrose, and nebulized salbutamol 10 to 20 mg

›Expect a citrate-related metabolic alkalosis after hemorrhage resolves

›Electrocardiographic surveillance during transfusion

›Hypocalcemia prolongs the QT interval and depresses contractility

›Hyperkalemia produces peaked T waves, PR prolongation, and QRS widening

›Anemia and hypotension can cause demand ischemia; do not reflexively route to the catheter laboratory or start anticoagulation

Antifibrinolytic and coagulopathy reversal

›Tranexamic acid

›1 g IV over 10 minutes, then 1 g IV infused over 8 hours

›Give early while hemorrhage is ongoing; benefit falls with delay

›Pediatric dose 15 mg/kg IV (maximum 1 g) then 2 mg/kg per hour

›Verify against current pediatric guideline before use

›Warfarin reversal

›Four-factor prothrombin complex concentrate 25 to 50 units/kg IV dosed by international normalized ratio and weight

›Vitamin K 10 mg IV by slow infusion

›Fresh frozen plasma 15 ml/kg only if prothrombin complex concentrate is unavailable

›Direct oral anticoagulant reversal

›Dabigatran: idarucizumab 5 g IV given as two 2.5 g doses

›Apixaban or rivaroxaban: andexanet alfa (low dose 400 mg bolus then 4 mg per minute; high dose 800 mg bolus then 8 mg per minute) or four-factor prothrombin complex concentrate 50 units/kg if andexanet is unavailable

›Activated charcoal 50 g if the last dose was within 2 to 4 hours

›Heparin and antiplatelet effects

›Protamine 1 mg per 100 units of unfractionated heparin given in the last 2 to 3 hours, maximum 50 mg, by slow IV push

›Protamine 1 mg per 1 mg of enoxaparin given within the last 8 hours partially reverses low molecular weight heparin

›Platelet transfusion and desmopressin 0.3 mcg/kg IV for antiplatelet-associated or uremic platelet dysfunction

Antimicrobial therapy

›Empiric regimen after cultures

›Piperacillin-tazobactam 4.5 g IV every 6 hours, or every 8 hours as a 4-hour extended infusion, renally adjusted

›Plus vancomycin 25 to 30 mg/kg IV loading dose then 15 to 20 mg/kg IV every 8 to 12 hours, targeting an area-under-curve to minimum inhibitory concentration of 400 to 600

›Add an echinocandin (micafungin 100 mg IV daily) empirically in the unstable patient or when Candida is suspected

›Alternatives and escalation

›Meropenem 1 to 2 g IV every 8 hours where extended-spectrum beta-lactamase risk or a beta-lactam allergy pattern applies

›Daptomycin 8 to 10 mg/kg IV daily, or linezolid 600 mg IV every 12 hours, if vancomycin cannot be used

›Fluconazole 800 mg IV load then 400 mg IV daily only for a stable patient with a susceptible isolate

›Primary fistula from Salmonella

›Ceftriaxone 2 g IV daily where no prosthetic graft is involved

›Prolonged therapy given the organism's affinity for diseased aorta

›Coordinate duration with infectious diseases

›Duration and source control

›Antibiotics do not substitute for graft excision and debridement

›Minimum 4 to 6 weeks of intravenous therapy after explant, then oral suppression, often lifelong if prosthetic material is retained

›Narrow therapy to operative culture and sensitivity results

Airway management considerations

›Resuscitate before intubation

›Have blood running and the patient volume-loaded toward the permissive target before induction

›Positive pressure and sympatholysis can precipitate cardiovascular collapse in compensated hemorrhagic shock

›Push-dose vasopressor ready: phenylephrine 50 to 200 mcg IV or epinephrine 10 to 20 mcg IV every 1 to 5 minutes

›Reduced-dose induction

›Ketamine 1 mg/kg IV, reduced to 0.5 mg/kg IV in shock

›Etomidate 0.15 to 0.3 mg/kg IV as an alternative

›Full-dose paralytic for first-pass success: rocuronium 1.2 mg/kg IV or succinylcholine 1.5 mg/kg IV

›Aspiration and technique

›Assume a stomach full of blood; use suction-assisted laryngoscopy with a large-bore rigid catheter

›Nasogastric decompression before induction if time allows

›Video laryngoscopy and the most experienced operator for the first attempt

›After intubation

›Lung-protective tidal volume 6 ml/kg predicted body weight

›Analgesia-first sedation with fentanyl; limit propofol, which lowers systemic vascular resistance and preload

›Recheck blood pressure within 1 minute of induction and treat hypotension immediately

Analgesia, sedation, and gastrointestinal measures

›Analgesia

›Fentanyl 25 to 50 mcg IV every 5 to 10 minutes titrated to effect; hemodynamically neutral

›Morphine 2 to 4 mg IV every 10 to 15 minutes is second line; histamine release, venodilation, and active metabolite accumulation in renal failure

›Avoid nonsteroidal anti-inflammatory drugs entirely, for example ibuprofen 400 mg orally: platelet inhibition, gastric mucosal injury, and acute kidney injury

›Antipyretic and non-opioid analgesia

›Paracetamol 1 g IV or orally every 6 hours, maximum 4 g per day

›Maximum 3 g per day if under 50 kg, chronic liver disease, malnutrition, or chronic high alcohol intake

›Fever control does not replace source control if it reflects graft infection

›Sedation for the ventilated patient

›Fentanyl infusion 25 to 100 mcg per hour as the analgesic base

›Add low-dose propofol 10 to 30 mcg/kg per minute, or dexmedetomidine 0.2 to 0.7 mcg/kg per hour, only once hemodynamics tolerate the fall in systemic vascular resistance and preload

›Target light sedation to allow frequent neurologic and perfusion checks

›Proton pump inhibitor and gastric decompression

›Pantoprazole

›80 mg IV bolus over 2 minutes

›Followed by infusion 8 mg per hour for 72 hours

›Intermittent 40 mg IV every 12 hours is acceptable if no infusion pump is available

›Step down to an oral agent after 24 hours without rebleeding and once the source is controlled

›Benefit is extrapolated from ulcer bleeding; it does not treat the fistula

›Nasogastric tube to decompress the stomach and monitor ongoing bleeding

›Do not use blind balloon tamponade devices; they address varices, not an aortic source

›Prokinetic before endoscopy

›Erythromycin 3 mg/kg IV over 20 to 30 minutes, given 30 to 90 minutes before endoscopy to clear gastric blood

›Check the QT interval first

›Metoclopramide 10 mg IV is an alternative

›Antiemetic

›Ondansetron 4 mg IV to reduce retching that can worsen bleeding

›Metoclopramide 10 mg IV is acceptable

›Avoid prochlorperazine 10 mg IV in the unstable patient because of hypotension

Definitive surgical and endovascular management

›Endovascular bridge

›Endovascular aneurysm repair or a covered stent graft can achieve rapid hemorrhage control in the unstable patient

›It is a bridge to staged open reconstruction once the patient is resuscitated

›Definitive endovascular-only repair leaves infected tissue and mandates lifelong suppressive antibiotics; reserve it for prohibitive open-surgical risk

›Open reconstruction options

›Graft excision, wide debridement, and extra-anatomic bypass (axillobifemoral) with aortic stump oversew

›In situ reconstruction with femoral vein (neoaortoiliac system), cryopreserved arterial allograft, or a rifampin-bonded prosthetic

›In situ approaches have lower reinfection rates in contemporary series and are increasingly preferred

›Bowel repair

›Primary duodenal repair or resection with wide debridement of devitalized tissue

›Omental flap interposition between the vascular repair and the bowel

›Wide drainage and a planned relook if contamination is heavy

›Feared complications to anticipate

›Aortic stump blowout after extra-anatomic bypass carries high mortality; reinforce and cover the stump with viable tissue

›Reinfection of an in situ graft

›Lower-extremity or visceral ischemia after reconstruction; monitor pulses and abdominal signs postoperatively

Iatrogenic harm avoidance

›Walk every routine intervention

›Intubation: reduced-dose induction, resuscitate first, pressor ready; standard-dose induction can arrest a compensated patient

›Sedation: propofol boluses and midazolam 1 to 2 mg IV boluses drop preload and systemic vascular resistance; use analgesia-first, minimal doses

›Fluid loading: large crystalloid volumes cause dilutional coagulopathy and dislodge the sealing clot; give blood, not saline

›Oxygen and pressors

›Oxygen: target 94 to 98 percent, 88 to 92 percent in chronic hypercapnia; hyperoxia does not help

›Vasopressors: acceptable only as a brief bridge alongside blood, never as a substitute for it

›Circulatory support and clot integrity

›Intra-aortic balloon pump: contraindicated, risks aortic and graft disruption and embolization

›Extracorporeal membrane oxygenation: not a bleeding solution and its anticoagulation is dangerous

›Anticoagulation and lytics

›Anticoagulation: hold and reverse for active hemorrhage; discuss graft thrombosis risk with vascular surgery, but hemostasis takes priority

›Fibrinolysis: absolutely contraindicated; reconsider any presumptive acute coronary syndrome or pulmonary embolism before giving lytics

›Analgesia and procedures

›Analgesia: fentanyl over morphine, and no nonsteroidal anti-inflammatory drugs

›Endoscopy: never dislodge an adherent duodenal clot outside a ready operating room

›Nasogastric placement is safe and useful; balloon tamponade devices are not indicated

When therapy is not working

›Ongoing hemorrhage despite balanced transfusion

›Rising pressor requirement, persistent lactate, and ongoing melena or hematemesis mean the fistula is not controlled

›Escalate to the operating room or aortic balloon occlusion now; do not order further imaging

›Re-verify calcium, fibrinogen, temperature, and platelet count as correctable amplifiers of bleeding

›Refractory shock with controlled external losses

›Consider a second site: retroperitoneal rupture, aortocaval fistula, or a missed non-aortic source

›Bedside echocardiography for tamponade, right ventricular failure, or hypovolemia

›Recheck for a transfusion reaction and for tension pneumothorax after central line placement

›Persistent sepsis after source control

›Fever and vasoplegia after graft excision suggest retained infected material, an undrained collection, or inadequate antifungal cover

›Repeat imaging for a drainable collection and add or broaden antifungal therapy

›Return to theatre for further debridement if a focus remains

›Failure to correct coagulopathy

›If viscoelastic testing stays abnormal despite ratio-based transfusion, give targeted fibrinogen and platelets and repeat tranexamic acid dosing

›Exclude hypothermia and acidosis as the reason factor replacement is failing

›Involve hematology for refractory disseminated intravascular coagulation

09Special Populations/sp56

Pregnancy

›Epidemiology and risk

›Aortoenteric fistula in pregnancy is exceptionally rare and is usually primary or driven by a connective tissue disorder

›Aortic wall stress rises in the third trimester from the hyperdynamic circulation and hormonal connective tissue change

›Marfan, vascular Ehlers-Danlos, and Loeys-Dietz syndromes raise aortic rupture and fistula risk

›Imaging

›Do not withhold computed tomography angiography for life-threatening hemorrhage; shield the uterus and accept the fetal dose

›Ultrasound and non-contrast magnetic resonance imaging are adjuncts only if the patient is stable

›Iodinated contrast is acceptable; document neonatal thyroid function follow-up

›Resuscitation adjustments

›Left lateral tilt of 15 to 30 degrees beyond 20 weeks to relieve aortocaval compression

›Maternal resuscitation takes priority; it is the best fetal resuscitation

›Continuous fetal monitoring once the mother is stabilized and the fetus is viable

›Resuscitative hysterotomy if maternal cardiac arrest beyond 20 weeks does not respond within 4 minutes

›Drugs in pregnancy

›Tranexamic acid 1 g IV then 1 g IV over 8 hours is considered safe in pregnancy and postpartum

›Piperacillin-tazobactam and vancomycin are acceptable; avoid aminoglycosides and fluoroquinolones unless the infection is otherwise untreatable

›Echinocandins are second line in pregnancy; weigh this against an untreated Candida graft infection

›Involve obstetrics, maternal-fetal medicine, neonatology, and vascular surgery together

Geriatric

›The typical patient

›Most secondary fistulae occur in patients in their seventies and eighties with open aneurysm repair years to decades earlier

›Presentation is often atypical: syncope, isolated anemia, or delirium rather than pain

›A blunted heart rate response from beta blockade masks the degree of shock

›Medication burden

›Anticoagulants and antiplatelets are common and worsen the bleed; reversal is slower and less complete

›Polypharmacy raises the risk of interactions with new antimicrobials

›Review for nephrotoxins before and after contrast

›Physiologic reserve

›Lower baseline renal and cardiac reserve; titrate transfusion to correct shock without precipitating circulatory overload

›Frailty affects operative candidacy, but an untreated fistula is uniformly fatal

›Involve the patient and family early in goals-of-care given the high perioperative mortality

›Thresholds that shift

›Accept a mean arterial pressure of 75 to 80 mmHg with chronic hypertension or cerebrovascular disease

›Treat new delirium as a marker of hypoperfusion or sepsis

›Use a higher transfusion threshold, around hemoglobin 80 g/l, with concurrent acute coronary syndrome

Pediatrics

›Causes in children

›Ingested foreign body, especially a button battery or sharp object, eroding the esophagus into the aorta (aortoesophageal fistula)

›Prior congenital cardiac or aortic surgery, coarctation repair, or an infected patch

›Connective tissue disease and, rarely, primary infection

›Presentation

›The Chiari triad variant: mid-thoracic or retrosternal pain, a sentinel arterial hemorrhage, then exsanguination after a symptom-free interval

›Any arterial-appearing hematemesis after battery ingestion is an emergency until proven otherwise

›Do not wait out the symptom-free interval

›Resuscitation dosing

›Packed red cell transfusion 10 to 20 ml/kg per bolus, reassessed after each

›Verify against current pediatric guideline before use

›Tranexamic acid 15 mg/kg IV (maximum 1 g) then 2 mg/kg per hour

›Verify against current pediatric guideline before use

›Calcium gluconate 50 to 100 mg/kg IV (maximum 3 g) for transfusion-related hypocalcemia

›Verify against current pediatric guideline before use

›Ketamine 1 to 2 mg/kg IV with rocuronium 1.2 mg/kg IV for intubation, using a reduced induction dose in shock

›Verify against current pediatric guideline before use

›Antimicrobials with an age qualifier

›Piperacillin-tazobactam 100 mg/kg per dose of the piperacillin component IV every 6 to 8 hours beyond the neonatal period

›Neonates: dose piperacillin-tazobactam by postmenstrual and postnatal age, and add ampicillin 50 mg/kg IV every 8 to 12 hours plus either gentamicin 4 to 5 mg/kg IV every 24 to 36 hours (level-guided) or cefotaxime 50 mg/kg IV every 8 to 12 hours, because ampicillin monotherapy is inadequate at this age

›Vancomycin 15 mg/kg IV every 6 hours in older children, with neonatal dosing intervals extended by postmenstrual age

›Involve pediatric surgery, cardiac surgery, and pediatric infectious diseases immediately

10Background/b48

Epidemiology

›Primary aortoenteric fistula

›Autopsy prevalence is roughly 0.04 to 0.07 percent

›It occurs in about 0.1 to 0.8 percent of untreated abdominal aortic aneurysms

›Around 80 percent involve the third or fourth portion of the duodenum

›Secondary aortoenteric fistula

›Complicates roughly 0.5 to 2 percent of aortic graft reconstructions, more after open repair than after endovascular repair

›Median presentation is 2 to 6 years after surgery, with a range from weeks to more than 15 years

›Most commonly arises at the proximal aortic anastomosis

›Outcomes

›Untreated aortoenteric fistula approaches 100 percent mortality

›Perioperative mortality after repair is roughly 30 to 40 percent

›One-year mortality remains high, in the range of 30 to 70 percent, with amputation and reinfection as major morbidities

›Site distribution and organisms

›Duodenum is most common, then jejunum and ileum, then colon, and rarely esophagus or stomach

›Common isolates: Escherichia coli, Salmonella, Staphylococcus aureus, streptococci, Bacteroides, and Candida

›Blood cultures are positive in up to half of infected secondary fistulae

Pathophysiology

›Mechanical erosion

›Pulsation of an aneurysm or graft against the fixed retroperitoneal duodenum causes pressure necrosis

›Adhesions from prior surgery tether bowel to the graft and concentrate shear

›An anastomotic pseudoaneurysm enlarges and erodes into adjacent bowel

›Infection

›Perigraft infection and biofilm on prosthetic material weaken the aortic and bowel walls

›Salmonella has a particular affinity for atherosclerotic and aneurysmal aorta

›Infection may precede the fistula as a graft infection or follow bowel contamination

›Two bleeding mechanisms

›Graft-enteric fistula: direct communication with the aortic lumen or suture line produces torrential, often fatal hemorrhage

11Patient Discharge Instructions/pdi36

When discharge is appropriate

›Very narrow circumstances

›Discharge applies only when aortoenteric fistula has been confidently excluded and a clear alternative low-risk source is identified and treated

›Any patient with an aortic graft or aneurysm and unexplained gastrointestinal bleeding is admitted, not discharged

›A single herald bleed is never grounds for discharge

›Before any discharge

›Hemoglobin stable on two measurements at least 6 hours apart

›Definitive upper and lower endoscopy has identified and treated the source

›Vascular surgery has documented that fistula is excluded

›Safety net

›Ensure reliable transport, a support person at home, and a working phone

›Confirm follow-up appointments are booked before leaving

›Provide written and verbal instructions with a named contact

copy discharge instructions

›Why you were seen

›You had bleeding from your gut, and we checked whether a blood vessel near your bowel was involved

›Because you have an aortic aneurysm or an aortic graft, this needs close follow-up even though the bleeding has settled

›A small warning bleed can come before a large one

›Return at once and call emergency services for any of these

›Vomiting blood, or material that looks like coffee grounds, even once

›Black tarry stools, or visible blood in the stool, even once

›Fainting, near-fainting, a racing heartbeat, cold sweats, or new confusion

›New or worsening abdominal or back pain, or a pulsing feeling in the abdomen

›A temperature of 38.0 degrees Celsius or higher, shaking chills, or drenching night sweats

›Medicines

›Take your acid-reducing tablet, for example omeprazole 20 to 40 mg once daily, exactly as prescribed

›If you were anemic, take iron, for example ferrous sulfate 325 mg once daily, and attend the follow-up blood test

›For pain, paracetamol 1 g up to four times a day, and no more than 3 g in 24 hours if you have liver problems, low body weight, or drink alcohol regularly

12References/r24

Society guidelines and consensus statements

›European Society for Vascular Surgery

›2020 Clinical Practice Guidelines on the Management of Vascular Graft and Endograft Infections, European Journal of Vascular and Endovascular Surgery

›Covers diagnosis, in situ versus extra-anatomic reconstruction, and antimicrobial duration

›Management of Aortic Graft Infection Collaboration

›2016 case definition for aortic graft infection, Lyons and colleagues, European Journal of Vascular and Endovascular Surgery

›Combines clinical or surgical, radiologic, and laboratory criteria

›Society for Vascular Surgery

›2018 Practice Guidelines on the Care of Patients with an Abdominal Aortic Aneurysm, Journal of Vascular Surgery

›Includes surveillance and graft-related complication management

›American College of Gastroenterology

›2021 Clinical Guideline on Upper Gastrointestinal and Ulcer Bleeding, American Journal of Gastroenterology

›International consensus recommendations on nonvariceal upper gastrointestinal bleeding, Barkun and colleagues, 2019, Annals of Internal Medicine

Landmark trials and key evidence

›CRASH-2

›2010, Lancet: tranexamic acid within 3 hours reduced all-cause and bleeding mortality in trauma hemorrhage without an increase in vascular occlusive events

›Basis for early antifibrinolytic use in noncompressible hemorrhage

›PROPPR

›2015, Journal of the American Medical Association: a 1:1:1 versus 1:1:2 plasma to platelet to red cell ratio showed no difference in 24-hour or 30-day mortality, but more hemostasis and fewer deaths from exsanguination with 1:1:1

›WOMAN trial

›2017, Lancet: tranexamic acid reduced death due to bleeding in postpartum hemorrhage, with the greatest benefit when given early

›UK-REBOA

›2023, Journal of the American Medical Association: resuscitative endovascular balloon occlusion of the aorta plus standard care did not improve, and may have worsened, 90-day mortality in trauma, supporting only a highly selective bridging role

›Reconstruction outcome series

›Neoaortoiliac system reconstruction with femoral vein, Clagett and colleagues, reporting durable infection-resistant repair

›Comparative series of in situ versus extra-anatomic repair for aortoenteric fistula, Batt and Kakkos and colleagues, showing lower reinfection with in situ techniques

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed September 13, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.