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Aortoenteric fistula (AEF) is a rare but catastrophic vascular condition that poses significant diagnostic and management challenges for clinicians, particularly vascular surgeons and critical care teams. This condition is classified into primary and secondary forms—primary AEF arises from the native aorta, typically associated with an aortic aneurysm. In contrast, secondary AEF is a complication of prior aortic reconstructive surgery, often involving prosthetic graft erosion into the gastrointestinal tract. The duodenum is the most frequent communication site, especially its second portion. Patients typically present with upper gastrointestinal bleeding, abdominal or back pain, and a history of aortic pathology or intervention. When left untreated, AEF is almost universally fatal. Even with prompt recognition and intervention, morbidity and mortality remain high, despite advances in operative techniques, antibiotic therapy, and critical care. Rapid identification and immediate management are essential to survival, often requiring endovascular repair as a bridge to definitive open surgical correction. This educational activity is designed to equip healthcare professionals with the knowledge and skills to effectively recognize, diagnose, and manage aortoenteric fistula. Clinicians learn to identify early warning signs, differentiate between primary and secondary AEF, and apply appropriate diagnostic imaging and hemodynamic stabilization strategies. The course emphasizes evidence-based decision-making, interprofessional collaboration, and timely coordination between vascular surgery, gastroenterology, radiology, critical care, and nursing teams. By strengthening these competencies, participants will enhance patient-centered care, improve diagnostic accuracy, and optimize outcomes in this life-threatening vascular emergency. Objectives: Identify early clinical signs and symptoms suggestive of aortoenteric fistula, including sentinel bleeding and hemodynamic instability. Differentiate between primary and secondary aortoenteric fistulas based on patient history, surgical background, and imaging characteristics. Screen high-risk individuals with prior aortic grafts or aneurysms for potential fistula formation using appropriate diagnostic modalities. Communicate effectively across surgical, radiologic, and critical care teams to ensure timely diagnosis and intervention.

Differentiate between primary and secondary aortoenteric fistulas based on patient history, surgical background, and imaging characteristics. Screen high-risk individuals with prior aortic grafts or aneurysms for potential fistula formation using appropriate diagnostic modalities. Communicate effectively across surgical, radiologic, and critical care teams to ensure timely diagnosis and intervention. Access free multiple choice questions on this topic.

Aortoenteric fistula (AEF) is a rare but catastrophic cause of massive upper gastrointestinal (GI) bleeding, associated with exceedingly high morbidity and mortality rates. The condition involves abnormal communication between the aorta and the GI tract, most commonly between the third or fourth portion of the duodenum and the aorta. AEFs are classified as either primary—arising spontaneously between a native aortic aneurysm and the adjacent bowel—or secondary, which occur far more frequently following previous aortic reconstructive surgery. Secondary AEFs most often develop when a synthetic graft erodes into the adjacent intestinal wall, typically the duodenum, due to infection, chronic mechanical irritation, or pressure necrosis at the graft–bowel interface.[1] Clinically, the presentation of AEF is variable but classically includes upper GI bleeding, which may manifest as a herald bleed, an initial, often self-limited hemorrhage that precedes catastrophic exsanguination. Other symptoms may include abdominal pain, fever, or sepsis, especially in the context of a prior aortic operation or known aortic aneurysm. Given the potential for rapid hemodynamic deterioration, AEF constitutes a surgical emergency requiring prompt recognition and intervention. Management is anchored in rapid diagnosis and early repair, either by open surgical reconstruction or endovascular stent-grafting. Endovascular repair offers a less physiologically taxing, temporizing measure to stabilize the patient, often serving as a bridge to definitive open surgery once infection control and hemodynamic stability are achieved. Despite advances in diagnostic imaging and repair techniques, complication rates remain high, and mortality often exceeds 30% to 50% in reported series. The first description of an AEF was made by the British surgeon Sir Astley Cooper in 1829, marking one of the earliest recognized vascular-enteric pathologies in the history of surgery.

AEFs arise from either primary or secondary causes. Primary fistula formation occurs spontaneously through a combination of direct frictional mechanical forces and aortic inflammation.[2] Secondary etiologies are much more common than primary etiologies. Secondary AEFs occur after open or endovascular aortic surgical intervention, typically after placement of synthetic aortic graft material.[3] The duodenum, particularly the third and fourth segments, where the aorta and duodenum are most intimately associated, is the most common site for developing an AEF.

AEFs are a rare phenomenon. In the age of endovascular and open repair of the aorta, secondary AEFs have overtaken primary AEFs in incidence. The incidence of primary AEF is between 0.04% to 0.07%. Secondary AEFs have been reported to occur in 0.36% to 1.6% of patients treated surgically for their aortic disease.[4][5][6] The mean age of patients with AEFs is 61, and AEFs are more common in men than women. This finding is consistent with increased abdominal aortic aneurysm (AAA) development rates and the greater frequency of AAA repair in men.[7] Primary and secondary AEFs occur in male-to-female ratios of 3:1 and 8:1, respectively.[7]

As mentioned, AEFs form by either primary or secondary causes. In primary cases, aneurysmal development is the most common cause of mechanical thinning of the aortic and enteral outermost layers as they rub against each other with each successive cardiac pulsation and GI peristalsis, respectively.[8] The presence of foreign bodies and tumors may also initiate or exacerbate this mechanical degradation. Inflammation, too, has been identified to exacerbate this adjacent erosion with a variety of etiologies, including mycotic aneurysms, sepsis, syphilis, salmonella, and tuberculosis.[9][10][11][12][13] Secondary AEFs most commonly form following aortic stent-graft placement. The proximity of the graft material to the neighboring enteral tract allows for mechanical rubbing, which can result in erosion into the enteral tract when not sufficiently bolstered by soft tissue. This erosion can be rapidly exacerbated as enteral bacteria translocate into the bloodstream and seed the graft, leading to fistula development, sepsis, and graft infection.[14] AEFs typically form at a single discrete location, but several simultaneous fistulas have been reported.[8][15] The most common location of the GI tract for primary AEF is the third and fourth portions of the duodenum (54%). Primary AEF has also been found in the following locations: the esophagus (28%), the small and large bowel (15%), and the stomach (2%).[8] Similar to primary AEF, the most common location seen for secondary AEF is the distal duodenum and proximal jejunum. However, multiple GI sites, depending on the location of the aortic graft, can be involved in secondary AEF.

A thorough history and physical examination are essential for evaluating a suspected AEF, though findings are often nonspecific and may overlap with those of other causes of upper GI bleeding. The classic presentation, Chiari triad, consists of gastrointestinal bleeding, abdominal pain, and a pulsatile abdominal mass; however, this triad is observed in only about 6% to 12% of patients at presentation, limiting its diagnostic utility.[16][17] Classically, AEFs begin with a minor “herald bleed,” a self-limited episode of hematemesis or melena that may precede catastrophic hemorrhage by hours to days. This early, transient bleeding occurs when the fistulous tract is temporarily tamponaded by thrombus formation, providing a critical but often missed diagnostic window. That said, many patients initially present with massive overt hemorrhage, underscoring the variability and potential sudden lethality of this condition.[16][17] Throughout history, clinicians should carefully assess for risk factors, such as prior aortic reconstructive surgery or known aneurysmal disease, as secondary AEFs typically occur months to years after aortic graft placement. Reports describe onset ranging from 2 weeks to over 10 years postoperatively.[18] Other pertinent historical details include recurrent fevers, sepsis of unknown origin, or previous unexplained GI bleeding. Aortoenteric erosion (AEE) must also be distinguished from AEF. While AEFs present with massive, acute hemorrhage, AEE typically manifests as chronic, intermittent bleeding and may be accompanied by recurrent bacteremia from enteric organisms—strongly suggesting infection of an existing aortic graft.[18] On physical examination, findings vary based on the acuity of presentation. Patients may exhibit hemodynamic instability, tachycardia, hypotension, pallor, diaphoresis, or evidence of hemorrhagic shock. Abdominal examination can reveal localized tenderness, a pulsatile or tender mass, or occasionally signs of infection around a prior surgical incision. In cases of massive bleeding, peritoneal signs or abdominal distension may develop secondary to intraabdominal hemorrhage. Although no single physical finding is diagnostic, maintaining a high index of suspicion is paramount, especially in any patient with a history of aortic surgery or aneurysmal disease presenting with GI bleeding.[1][16][17][18]

When AEF is suspected in the hemodynamically unstable individual, one should proceed immediately to surgery without further diagnostic studies; however, if no history of abdominal aortic aneurysm (AAA) or prior surgical repair of the aorta is known, initial assessment of the abdomen by ultrasonography for aneurysmal disease in an unstable patient with ongoing resuscitation before proceeding to the operating room may be performed. A bedside ultrasound is useful for detecting an AAA. Still, because of bowel gas and the enteral distention commonly associated with AEF, it is a poor diagnostic tool for AEF. In an individual who is hemodynamically stable with ongoing GI bleeding, upper esophagogastroduodenoscopy (EGD) has been reported as the first procedure; unfortunately, EGD is a poor diagnostic tool for AEF, with a sensitivity of only approximately 50%.[19] Therefore, in a stable individual with ongoing bleeding and risk factors for AEF, the initial diagnostic test should be computed tomographic angiography (CTA), which is highly sensitive and specific.[8][20][21] CTA is also the preferred imaging modality compared to digital subtraction angiography (DSA).[22] Once a CTA has been performed to rule out AEF, it is appropriate to proceed with EGD in a hemodynamically stable individual to evaluate for other potential causes of GI bleeding. Colonoscopy has limited use in diagnosing AEF but may be considered when a patient’s presentation is more consistent with a lower GI bleed or when an alternative diagnosis of the colon is more likely.[23] Identifying AEFs remains difficult despite proper imaging, and many diagnoses are not made until autopsy.[24][25]

Managing AEF is centered on rapid diagnosis, aggressive surgical intervention, and meticulous infection control, as the condition remains uniformly fatal if untreated. Initial management focuses on hemodynamic stabilization, including airway protection, large-bore intravenous access, and balanced blood product resuscitation with a 1:1:1 ratio of packed red blood cells, platelets, and fresh frozen plasma.[26][27] Anticoagulation reversal should be performed if applicable. Blood cultures must be drawn promptly, and broad-spectrum antibiotics must be initiated and tailored once specific microbial growth is identified.[26] If Clostridium septicum is isolated, colonic evaluation for occult malignancy, typically via colonoscopy, is indicated.[28] Hemodynamically unstable individuals should proceed directly to the operating room, whereas those who can tolerate a brief diagnostic evaluation may undergo CTA to confirm the diagnosis and guide operative planning.[17][18] Definitive management requires controlling hemorrhage, eradicating infection, restoring aortic continuity, and repairing the enteric tract. Two major approaches are open surgical repair and endovascular aneurysm repair (EVAR). Open surgery remains the gold standard in patients with infection or those able to tolerate the physiologic stress of laparotomy. This approach allows complete debridement of infected tissue, primary repair of the enteric defect, and, when necessary, explantation of infected grafts. Open repair is associated with a lower rate of late sepsis (19%) than EVAR (42%), likely due to direct source control.[29][30] However, open repair carries a higher in-hospital mortality (33.9%) than EVAR (7%).[30] EVAR provides a less invasive alternative, particularly for those who are unstable, with prohibitive operative risk, or those with hostile abdominal anatomy.[31] While EVAR can rapidly control bleeding, it introduces prosthetic material into a contaminated field, predisposing patients to chronic infection, recurrent sepsis, and prolonged antibiotic dependence.[32][33] Consequently, EVAR is best employed as a bridging strategy in secondary AEF or infected cases, allowing stabilization until the patient can undergo definitive open reconstruction.[34][35] Long-term suppressive antibiotics and percutaneous drainage of abscesses may be required for chronic graft infections.

Open repair is associated with a lower rate of late sepsis (19%) than EVAR (42%), likely due to direct source control.[29][30] However, open repair carries a higher in-hospital mortality (33.9%) than EVAR (7%).[30] EVAR provides a less invasive alternative, particularly for those who are unstable, with prohibitive operative risk, or those with hostile abdominal anatomy.[31] While EVAR can rapidly control bleeding, it introduces prosthetic material into a contaminated field, predisposing patients to chronic infection, recurrent sepsis, and prolonged antibiotic dependence.[32][33] Consequently, EVAR is best employed as a bridging strategy in secondary AEF or infected cases, allowing stabilization until the patient can undergo definitive open reconstruction.[34][35] Long-term suppressive antibiotics and percutaneous drainage of abscesses may be required for chronic graft infections. The operative technique choice depends on the contamination severity and the patient's stability. In primary AEF with minimal contamination, in situ aortic replacement with cryopreserved homografts or antibiotic-soaked Dacron, combined with local debridement and prolonged antimicrobial therapy, is preferred. In cases of gross contamination or sepsis, optimal management involves aneurysm resection, extensive retroperitoneal debridement, omentoplasty, and extraanatomic bypass reconstruction. For secondary AEF, options include graft excision alone, in situ replacement, autogenous vein reconstruction (eg, neoaortoiliac system), or extraanatomic revascularization with lifelong suppressive antibiotics.[34] Prevention is essential. The United States Preventive Services Task Force recommends a 1-time screening ultrasound for all men aged 65 to 75 who have ever smoked to detect AAA early and allow elective repair before fistula formation.[36] During open AAA repair, the graft must be isolated from the duodenum by reapproximating the aneurysmal sac or creating an omental or vascularized pedicle flap to prevent erosion.[37] Survivors of AEF repair require lifelong aortic surveillance due to the risk of recurrent infection or graft complications.[38] Despite advances in surgical and endovascular techniques, early recognition, prompt intervention, and vigilant postoperative monitoring remain the cornerstones of improving survival in this highly lethal condition.

The differential diagnoses for AEF include: Graft infection Infected (mycotic) aortic aneurysm Septic aortitis Retroperitoneal fibrosis Inflammatory bowel disease Intestinal tubular adenomas Angiodysplasia Peptic ulcer disease Colon cancer

Despite advances in cross-sectional imaging and endovascular techniques, the prognosis for those who develop an AEF remains profoundly poor. In 1 review of those treated for aortoduodenal fistula in the 1980s, overall survival was an abysmal 14%, with 36% of patients undergoing treatment dying in the immediate perioperative period.[39] More recent analyses have shown some improvement in mortality, with 1 report demonstrating a 50% mortality rate among patients undergoing treatment for AEF within 60 days of repair, while another, slightly larger series reported a 30-day all-cause mortality rate of 43% among those who underwent repair.[40] Overall, the mortality rate for those developing AEFs is unknown. Still, it is certainly underestimated here as the aforementioned survival rates include only those patients for whom a diagnosis was made and surgical repair attempted. Many patients die before a correct diagnosis can be made, excluding them from the studies presented here.

Several complications can occur secondary to the development of an AEF and to the associated treatment. Here, the most common complications following AEF repair are presented: Hemorrhagic shock Septic shock and multiorgan failure Myocardial infarction and arrhythmias Aortic stump blowout Graft infection Enteral leak Recurrent bacteremia and sepsis [25]

Deterrence and patient education in the context of AEF primarily focus on risk mitigation, early recognition, and preventing recurrence. Because secondary AEFs most commonly arise as late complications following aortic reconstructive surgery, patient education should begin in the perioperative period and continue throughout long-term follow-up. Patients must be counseled on the importance of lifelong surveillance imaging, typically CTA or ultrasound, to monitor graft integrity, detect aneurysmal dilation, and identify signs of infection before catastrophic rupture or erosion. They should be educated to recognize warning symptoms such as new or recurrent GI bleeding (hematemesis, melena), unexplained fever, abdominal pain, or signs of sepsis, which may herald graft infection or fistula formation. Preventive strategies should also emphasize modification of underlying risk factors. Patients with atherosclerotic or aneurysmal disease should receive guidance on smoking cessation, blood pressure control, and lipid management to prevent progression of vascular disease. In cases of Clostridium septicum bacteremia, clinicians must educate patients about the need for colonoscopy to evaluate for malignancy and emphasize adherence to antibiotic regimens to eradicate the infection and prevent recurrence. For those undergoing aortic reconstruction, surgeons must reinforce the importance of routine follow-up, as secondary AEFs may manifest anywhere from 2 weeks to more than 10 years postoperatively.[18] Ultimately, deterrence and patient education are achieved through coordinated, multidisciplinary communication that links vascular surgeons, primary care clinicians, infectious disease specialists, and patients to ensure ongoing surveillance, prompt recognition of symptoms, and timely intervention, thereby improving survival outcomes.

The classic triad of AEFs, which includes GI bleeding, abdominal pain, and a palpable abdominal mass, is rarely seen in clinical practice. Not all AEFs bleed during their initial presentation, and many will never bleed during a patient’s illness. AEF must be kept in the differential diagnosis for any patient with a known history of aortic aneurysm or aortic repair who presents with GI bleeding, sepsis, abdominal pain, or hemorrhagic shock, even if an alternative source of GI bleeding has been identified.[8]

Effective management of AEF requires seamless interprofessional collaboration and rapid, coordinated decision-making among all healthcare team members. Clinicians, particularly vascular surgeons, interventional radiologists, and critical care specialists, must work together to establish the diagnosis, stabilize the patient, and determine the most appropriate repair strategy, whether endovascular or open.[41] Advanced practitioners and nurses play vital roles in early recognition of sentinel bleeding, ongoing hemodynamic monitoring, and postoperative surveillance for recurrent infection or hemorrhage. Clear, structured communication between teams ensures prompt activation of massive transfusion protocols, optimization of antibiotic coverage, and continuous assessment of end-organ perfusion, all directly influencing survival. Pharmacists ensure timely delivery and appropriate dosing of broad-spectrum antibiotics, anticoagulation management, and hemodynamic support agents. Anesthesiologists and critical care clinicians coordinate resuscitation and ventilatory strategies to minimize physiologic stress during and after repair. Postoperatively, multidisciplinary rounds enhance patient safety by facilitating shared updates on infection control, wound management, and nutritional support. By fostering real-time communication, mutual situational awareness, and adherence to evidence-based pathways, the interprofessional team improves outcomes and patient-centered care—ensuring that rapid intervention, continuity, and compassion remain central to managing this highly lethal vascular emergency.