Survival After a Primary Ilio-Enteric Fistula and Cardiac Arrest in a Man Who Had Renal and Pancreatic Transplants

Abstract

Background: Gastrointestinal bleeding (GIB) is a frequent emergency department (ED) presentation with rare but life-threatening causes, including arterio-enteric fistulas (AEF), which account for less than 1% of GIB cases. Ilio-enteric fistulas are even more rare but have similar morbidity and mortality. Methods: This case report describes a 51-year-old male with a history of type 2 diabetes mellitus, diabetic retinopathy, and pancreas–kidney transplantation who presented to the ED with a massive hemorrhage from an ilio-enteric fistula. Despite initial stability, the patient became hypotensive and deteriorated to pulseless electrical activity (PEA) arrest. Despite multiple arrests, he survived and was discharged to a rehabilitation facility. Results: AEFs, particularly iliac-enteric fistulas, are diagnostically challenging and often present with nonspecific symptoms. Diagnostic imaging, especially CT angiography, is crucial, although initial non-contrast CT may miss the diagnosis. Early consultation with vascular surgery is essential for managing these patients. Conclusions: This case underscores the need to consider AEF in the differential diagnosis of GIB, particularly in post-transplant patients, and highlights the importance of prompt intervention.

1. Introduction

Gastrointestinal bleeding (GIB) is a common reason patients visit the emergency department (ED), with 397.5/100,000 ED visits related to a GIB in 2019 [1]. Rare but significantly lethal causes include arteriovenous malformations, bleeding gastric ulcers, and arterio-enteric fistulas (AEF), with AEFs accounting for less than 1% of all GIB [2,3].

AEFs are typically the result of atherosclerotic aortic aneurysm erosion into the adjacent bowel, most commonly the third and fourth portions of the duodenum [4]. Primary AEFs occur in patients with aortic wall infections, seeding due to bacteremia, or tumors that exacerbate mechanical degradation [5]. Secondary AEFs occur after surgical intervention on the aorta or one of its branches, typically following the placement of a synthetic graft material [6]. Further characterizations are described below (Table 1).

Under-represented in medical literature but increasing in incidence are secondary AEF complications in patients who underwent organ transplantation [7,8,9,10,11,12,13,14]. In the published cases, patients frequently underwent either pancreatic transplants or simultaneous pancreas–kidney transplantations (SPK) with subsequent AEFs occurring at the site of surgery [15,16,17,18,19]. What sets this case apart from all the others is that despite the history of a pancreas–kidney transplantation, the ilio-enteric fistula did not arise at anastomosis or aneurysm.

Table 1. Comprehensive summary table: aortoenteric fistulas (AEFs).

Category	Key Findings	References
Etiology	- Primary AEFs arise from aortic aneurysms, infections, or chronic inflammation. - Secondary AEFs occur postoperatively, particularly after aortic grafts or abdominal organ transplants (e.g., pancreas, kidney). - Rare causes include pelvic irradiation, malignancies, and anti-VEGF therapy (e.g., bevacizumab).	[4,5,6,14,20,21,22]
Clinical Presentation	- ‘Herald bleed’: small self-limiting bleed preceding massive hemorrhage. - Classic triad (infrequently seen): GI bleeding, abdominal pain, palpable mass. - Often presents as unexplained or recurrent GI hemorrhage, sometimes after recent vascular intervention.	[23,24,25]
Transplant- Associated AEFs	- Seen in pancreas/kidney transplant patients, particularly with failed or infected grafts. - Fistulas often occur between iliac artery anastomoses and the adjacent bowel. - Treatment includes graft removal, embolization, or endovascular repair, often requiring multidisciplinary coordination.	[9,10,11,12,13,17,19]
Diagnosis	- CT angiography (CTA) is the most sensitive imaging modality: Use of IV contrast is critical for identifying extravasation, pseudoaneurysms, or air adjacent to vessels; Non-contrast CT is useful to identify hyperdense blood or gas bubbles but has limited sensitivity. - Endoscopy may help in excluding other GI sources, though limited in identifying AEFs. - MR angiography and contrast-enhanced ultrasound may assist in equivocal cases or in renal impairment.	[25,26,27]
Management Strategies	- Endovascular treatment (e.g., stent-graft placement): Rapid bleeding control, especially in unstable patients; Serves as a bridge to definitive surgical repair. - Surgical treatment: Excision of infected graft or pseudoaneurysm; Extra-anatomic bypass (e.g., axillobifemoral) to re-establish blood flow; Direct aortic reconstruction with homograft or rifampin-soaked graft; Bowel resection if significant enteric contamination or ischemia.	[8,18,22,28,29,30]
Prognosis	- Mortality remains high, especially in secondary AEFs or delayed diagnosis. - Prognosis improves significantly with early recognition and multidisciplinary intervention.	[23,24,25]
Trends & Evolution	- Increasing cases arising from transplants, oncologic therapy, and endovascular procedures. - Shift toward minimally invasive interventions as first-line management, particularly in unstable patients. - Hybrid approaches (endo + open surgery) are gaining traction.	[1,2,6,18]

Table 1. Comprehensive summary table: aortoenteric fistulas (AEFs).

Category	Key Findings	References
Etiology	- Primary AEFs arise from aortic aneurysms, infections, or chronic inflammation. - Secondary AEFs occur postoperatively, particularly after aortic grafts or abdominal organ transplants (e.g., pancreas, kidney). - Rare causes include pelvic irradiation, malignancies, and anti-VEGF therapy (e.g., bevacizumab).	[4,5,6,14,20,21,22]
Clinical Presentation	- ‘Herald bleed’: small self-limiting bleed preceding massive hemorrhage. - Classic triad (infrequently seen): GI bleeding, abdominal pain, palpable mass. - Often presents as unexplained or recurrent GI hemorrhage, sometimes after recent vascular intervention.	[23,24,25]
Transplant- Associated AEFs	- Seen in pancreas/kidney transplant patients, particularly with failed or infected grafts. - Fistulas often occur between iliac artery anastomoses and the adjacent bowel. - Treatment includes graft removal, embolization, or endovascular repair, often requiring multidisciplinary coordination.	[9,10,11,12,13,17,19]
Diagnosis	- CT angiography (CTA) is the most sensitive imaging modality: Use of IV contrast is critical for identifying extravasation, pseudoaneurysms, or air adjacent to vessels; Non-contrast CT is useful to identify hyperdense blood or gas bubbles but has limited sensitivity. - Endoscopy may help in excluding other GI sources, though limited in identifying AEFs. - MR angiography and contrast-enhanced ultrasound may assist in equivocal cases or in renal impairment.	[25,26,27]
Management Strategies	- Endovascular treatment (e.g., stent-graft placement): Rapid bleeding control, especially in unstable patients; Serves as a bridge to definitive surgical repair. - Surgical treatment: Excision of infected graft or pseudoaneurysm; Extra-anatomic bypass (e.g., axillobifemoral) to re-establish blood flow; Direct aortic reconstruction with homograft or rifampin-soaked graft; Bowel resection if significant enteric contamination or ischemia.	[8,18,22,28,29,30]
Prognosis	- Mortality remains high, especially in secondary AEFs or delayed diagnosis. - Prognosis improves significantly with early recognition and multidisciplinary intervention.	[23,24,25]
Trends & Evolution	- Increasing cases arising from transplants, oncologic therapy, and endovascular procedures. - Shift toward minimally invasive interventions as first-line management, particularly in unstable patients. - Hybrid approaches (endo + open surgery) are gaining traction.	[1,2,6,18]

2. Case

A 51-year-old male patient with a past medical history of diabetes mellitus type 2 with diabetic retinopathy causing complete blindness and a pancreas–kidney transplantation in 2007 secondary to end-stage renal disease was presented to the ED by the Emergency Medical Services (EMS) complaining of generalized weakness, loose stools, and mild pressure-like discomfort in his lower abdomen, worsening over the previous three days. Initial vital signs included a blood pressure of 144/89 (108) mmHg, heart rate of 90 beats per minute, oxygen saturation of 92% on room air, and an oral temperature of 99 °F. He was mildly diaphoretic and pale. EMS noted they found him with dried blood on his feet and perineal region. His stool was guaiac-positive without frank blood. He was uncertain how long his stools had been bloody due to his blindness. His abdominal exam was without tenderness, guarding, or rigidity, and no pulsatile masses were appreciated. The remainder of the physical exam was unremarkable.

Shortly after the initial evaluation, the patient became hypotensive with MAPs in the 50 s. However, he maintained normal mentation without tachycardia. Two units of emergency-release blood were administered, and the patient’s blood pressure improved to 105/65 mmHg. A point-of-care Rapid Ultrasound for Shock and Hypotension exam did not demonstrate free intraperitoneal fluid, pericardial effusion, or an apparent aortic aneurysm. Laboratory results were notable for a hemoglobin of 5.7 g/dL, hematocrit of 18.1%, platelets at 333 K/µL, a WBC of 21.0 c/µL with neutrophilic predominance, and a BUN of 38 mg/dL with creatinine of 2.1 mg/dL.

Due to his renal history, the patient underwent a non-contrasted abdominal/pelvic CT scan. The scan demonstrated mild fat stranding of the small bowel in the right lower quadrant, suspicious for an infectious process. There was no evidence of bowel obstruction, bowel perforation, intraperitoneal free fluid, or an aortic aneurysm. Atherosclerotic calcifications were also present within the aortoiliac arteries.

After returning from radiology, the patient became more diaphoretic, tachycardic into the 110 s, and hypotensive with an MAP in the 50 s, and he developed altered mentation. The patient had a sizeable maroon-colored bowel movement and became pulseless despite electrical cardiac activity on telemetry (PEA). Advanced Cardiac Life Support was initiated and return of spontaneous circulation (ROSC) was achieved after 1 mg of epinephrine and 3 min of compressions. A massive transfusion protocol was initiated, and the patient was intubated for airway protection.

The patient was sent back to radiology for a CT angiogram of the abdomen/pelvis to help determine the source of the bleeding. This CT revealed contrast extravasation extending from the right common iliac artery into the small bowel, consistent with an iliac–enteric fistula and a significant, active bleed (Figure 1 and Figure 2). The CT imaging also showed atrophic native kidneys, consistent with the patient’s history of renal failure and a transplanted kidney in the left lower quadrant.

Vascular surgery emergently stented his right common iliac. Owing to his complicated history and renal transplant, he was transferred to a transplant center care center for continued management. Before transfer, he experienced two additional PEA arrests, with ROSC achieved shortly after each. The patient was ultimately discharged to a rehab center and continues to do well.

3. Discussion

AEFs are an uncommon cause of GIB and can be challenging to diagnose, particularly in patients who present with non-specific complaints [20]. The classic triad consists of abdominal pain, melena, and a pulsatile abdominal mass, although this complete triad only occurs in about 11% of cases [31]. Of patients who were ultimately diagnosed with an AEF, a range of 20–75% experienced a herald bleed followed by minor or intermittent GI bleeding [23]. Clinical manifestations of AEFs vary from gastrointestinal bleeding and abdominal pain to heart failure, which can be misattributed to other conditions [32]. AEFs have been estimated to have 30-day mortality as high as 58% in primary AEFs, even with appropriate intervention [33]. Advances in diagnostic imaging and surgical techniques have likely lowered this number, although mortality without treatment is 100%, which is why prompt identification and treatment can drastically improve outcomes [20].

An iliac–enteric fistula (IEF), a specific type of AEF, is an even more rare condition with experience limited to case reports and series [8]. A case series of 30 IEFs from 1987 found that 55% of primary AEFs were associated with aneurysmal disease and risk factors included prior arterial or bowel surgery, mycotic aneurysms, malignancy, foreign bodies, and radiation therapy [21,28]. A review of 932 aortoiliac repairs identified only one IEF that developed after surgery 28]. Fortunately, there is no difference in mortality between AEFs and IEFs [6,28].

Our patient did have a history of abdominal surgery and SPK, but no known aneurysm. Additionally, while he likely did have a herald bleed, this information was not known due to his blindness, attributing the frank blood as a seemingly innocuous history of “loose stools” during his initial history. Case reports have described an association of patients with simultaneous pancreas–kidney transplantations (SPK) or single-organ transplants with an AEF. Presentations vary, as previously described; however, in each of these prior cases, the cause of the AED was related to their transplant surgery or aortic anastomosis. Five to ten percent of SPK complications are related to vascular etiology, including renal artery or vein thrombosis, renal stenosis, lymphoceles, and aneurysms. The time of bleeding onset after an SPK ranges from two months to 18 years [9,10,11,13,14,15]. Each prior case noted fistulas involving the donor site or a location proximal to the surgical site, while our case was not related to either.

Evaluation of the patient with suspected AEF is challenging. The differential for this particular patient population includes but is certainly not limited to graft infection without fistula, gastrointestinal ulceration or perforation, transplant organ rejection with necrosis, pseudoaneurysm rupture, and bleeding from staple lines or surgical anastomoses. History and physical examination can help narrow the differential; however, the most effective way to assess the patient is via imaging. It should be noted that a patient with significant risk factors for an AEF who is unstable should ideally be taken to surgery immediately without further diagnostic studies. If medically stable, a CT angiography of the aorta (CTA) is the imaging modality of choice. Non-contrast CT scans are often the initial imaging method in evaluating suspected abdominal complaints, particularly in elderly patients, those with renal disease, or those with a history of renal transplant. In the absence of intravenous contrast, vascular structures, including AEFs, are challenging to evaluate, underscoring this imaging technique’s limitation [26,27].

CTAs have been reported to have a sensitivity as high as 93%, but it may be as low as 85.7% in diagnosing an AEF, and they are not without limitations [22,24]. One caveat is that CT technology has dramatically advanced over the last few decades, and the specificity and sensitivity may be improved with modern technology. Exploratory laparotomies have the highest specificity and sensitivity, but are reserved for high-risk patients [25].

While a CTA may not always identify the fistula, there are secondary findings that can be made on a CT that should raise concern, including the effacement or blurred borders of fatty planes around arteries, soft tissue collections around the aorta, ectopic gas within or adjacent to the aorta, and intravenous contrast within the gastrointestinal lumen or around the aorta, among other less likely and more non-specific findings [23]. Unfortunately, a CTA cannot adequately rule out an AEF. For patients with significant gastrointestinal bleeding and a history of aortic surgery, early consultation with vascular surgery is recommended, even if CTA results are equivocal [27].

Treatment for AEFs includes open surgery with debridement and the reconstruction of the vessel, the in situ replacement of the graft, endovascular aortic repair with stent-grafts, embolization of the bleeding artery, and temporary tamponade of the bleed with balloon-catheter artery occlusion [29]. Endovascular techniques have been employed in managing AEFs, including in emergent situations. While these techniques can stabilize patients, the overall prognosis remains poor, often due to comorbidities or rebleeding [29]. Rebleeding is possible and can be managed by various methods, including rectal tamponade, artery embolization, and laparotomy with ligation of the bleeding branches of affected iliac arteries.

Ultimately, this patient was managed appropriately, and survived because of coordinated care amongst a multi-specialty team. While management options do include direct operative intervention, imaging modalities including contrasted computed tomography, non-contrasted computed tomography, and ultrasonography can aide in localizing the site of bleeding, thus guiding surgical approach [30]. This case highlights the benefit of using contrasted computed tomography in a patient with prior pancreas–kidney transplantation.

4. Conclusions

AEFs are diagnostically challenging. Without treatment, mortality is 100%. The patient discussed in this case highlights this difficulty, as the patient lacked usual risk factors, contrast infusion was a relative contraindication with his renal transplant history and elevated creatinine, and even after diagnosis, his AEF was not proximal to his surgical site, nor did it involve the donor grafts. Despite this, in addition to multiple cardiac arrests, the patient was fortunate to undergo excellent recovery without sequelae.