Cancer-Associated Aorto-Enteric Fistula
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- Cite this article as:
- Singh, S., Ladabaum, U., Hovsepian, D.M. et al. Dig Dis Sci (2012) 57: 625. doi:10.1007/s10620-011-1945-y
Case Presentation and Evolution
A 46 year-old woman presented to the emergency department with hematemesis associated with syncope. The patient’s only complaint was severe and diffuse abdominal pain that prohibited her from providing further history. According to her family, she had melena while at home and was found in the bathroom unconscious. The patient spontaneously regained consciousness before arrival of the emergency medical services. She denied any NSAID or aspirin use, although she was on daily enoxaparin for deep vein thrombosis that was extending from her inferior vena cava to her femoral vein. On her arrival at the emergency department, gastroenterology, general surgery, interventional radiology, and intensive care unit teams were consulted about the emergency.
The patient’s prior medical history started with diagnosis with stage IIIC (T3N2M0) sigmoid adenocarcinoma two years previously, in the setting of rectal bleeding. She underwent a left hemi-colectomy, partial cystectomy, and left ovarian and left fallopian tube resection. She subsequently received adjuvant oxaliplatin, capcitabine, and bevacizumab. She was also treated with radiation therapy of the peri-aortic lymph nodes because, at the time of surgery, four out of 21 lymph nodes were positive. Four months before admission, the patient presented with a small bowel obstruction resulting in operative intervention that included lysis of adhesions, partial resection of the ileum with side-to-side entero-enterostomy, cystoscopy with left ureteral catheter, and lymph node dissection. The histology demonstrated involvement of the retroperitoneal and peri-aortic lymph nodes and ileal serosa. Consequently, she was treated with irinotecan and bevacizumab.
During the four weeks before this most recent admission, she had been hospitalized several times, most recently four days before admission, with nausea, vomiting, and abdominal pain that were attributed to gastroparesis secondary to narcotics, with chemotherapy and paraneoplastic phenomena considered as additional possible contributing factors. Specifically, the patient’s generalized abdominal pain was attributed to her metastatic disease and gastroparesis.
The patient did not have any other pertinent medical, social, or family history. Her medications included enoxaparin, dilaudid, pantoprazole, desipramine, compazine, gabapentin, lorazepam, lomotil, ondansetron, metoclopramide, and fentanyl patch.
She had several gastrointestinal studies leading to her most recent presentation. A colonoscopy performed one year before this admission did not demonstrate any abnormalities. A gastric emptying study performed two months before admission showed 52% retention at 4 h (normal <10%). During that same hospitalization, the patient had an upper endoscopy showing granular gastric mucosa with histology showing H. pylori-negative mild chronic gastritis. Two months before admission, a brain MRI scan did not reveal metastatic disease.
On examination in the emergency department, the patient was afebrile, tachycardic (HR 139), hypotensive (89/62), tachypneic (RR 28), with normal oxygen saturation (98%). During the examination, she experienced repeated bouts of hematemesis and hematochezia. Naso-gastric lavage yielded 500 mL bright red liquid blood that could not be cleared. She was anicteric and had no stigmata of chronic liver disease. Her cardiopulmonary exam was notable for regular tachycardia without any murmurs, rubs, gallops, and bilaterally clear lungs on auscultation. Her abdominal examination showed large well-healed laparotomy scars, soft, with tenderness on deep palpation, active bowel sounds, and no organomegaly. Rectal exam revealed maroon liquid blood.
Her complete blood count and basic metabolic panel were notable for a decrease in hemoglobin from 10.2 g/dL five days before admission to 5.2 g/dL, BUN 11 mg/dL, and creatinine 0.8 mg/dL. The patient’s INR was 1.8. She was transfused with 13 units of packed red blood cells, with a rise in hemoglobin to 8.0 g/dL, with fresh frozen plasma in accordance with procedures for massive blood transfusions.
After recovery, a CT scan revealed new liver metastases, multiple micro-abscesses within the small bowel mesentery, new superior mesenteric and splenic venous thrombosis that was occlusive, extension of her IVC thrombus into the right renal vein, and a new thrombus in her left subclavian vein. Over the next two weeks, she developed progressive renal failure and continued to clinically deteriorate resulting in transition to comfort care. She died in hospital three weeks later.
First described in 1839 by Sir Astley Cooper, aorto-enteric fistulae typically present with a characteristic triad of abdominal pain, pulsatile abdominal mass, and gastrointestinal bleeding, although all three features are only present in 11% of patients . Aorto-enteric fistula is a rare cause (<1:1,000) of gastrointestinal hemorrhage. Overall, one-third of patients with aorto-enteric fistulae in the setting of cancer have their primary malignancy arising in the gastrointestinal tract. The thoracic aorta is nine times more likely to be affected by an enteric fistula than is the abdominal aorta, because of the relative frequency of cancer in the nearby esophagus and the length of adjacency .
Aorto-enteric fistulae of the abdominal aorta are usually associated with atherosclerotic abdominal aortic aneurysms, radiation therapy, malignancy, infection, trauma, and tuberculosis. Fistulae that occur after abdominal aortic aneurysm repair are much more common, occurring in up to 1.6% of patients. They typically involve the duodenum (81%) and the ileum (10%), because of the close proximity of these two structures at these locations.
With myriad possible sources of gastrointestinal hemorrhage, diagnosis of aorto-enteric fistula can easily be overlooked but should be kept in mind. Although 25% of patients with aorto-enteric fistulae present with hemodynamic instability during their first episode of bleeding, most patients will have a “herald” or “sentinel” bleed hours to months before their index presentation. Ultimately, most patients (56%) are diagnosed when they present with hemorrhagic shock. Unfortunately, endoscopy, which is the primary modality for diagnosis and treatment of upper and lower gastrointestinal bleeding, has a disappointingly low yield and it can delay definitive intervention when the source is an aorto-enteric fistula .
The sensitivity of upper endoscopy is less than 40%, because the fistula may not be visualized in the absence of active bleeding or, in cases of prior AAA repair, an obvious rent with graft material or suture is not visible in the field. Laparotomy can only locate the point of bleeding in 50–73% of patients . Historically, diagnosis of aorto-enteric fistula has been made post-mortem in half of patients because of these challenges in diagnosis. Contrast-enhanced CT scanning is now the diagnostic modality of choice in this setting because of its superior sensitivity (80–90%) and specificity (100%) .
The placement of a balloon catheter for tamponade is an effective bridge to definitive therapy, but it is not effective by itself (as it may be with smaller arteries), so ultimately open surgery or endovascular repair are required. The choice of approach depends on the clinical setting and institutional expertise. Traditionally, the surgical steps involve aortic ligation above the fistula, removal of any graft material that is present, resection of the affected bowel and reanastomosis, and placement of an extra-anatomic bypass graft.
In this case, given the overall severity and extent of the disease, the high mortality of surgery (25–90%) and complications such as amputation (5–25%) and aortic stump rupture (10–50%) were prohibitive risks for a patient with incurable cancer. The development of endovascular stent–grafts in general has provided an expedient solution to this problem [6, 7].
However, for patients presenting with signs and symptoms of infection, 75% will develop infection after stent–graft repair, presumably because the field is contaminated. Even when there is no evidence of infection, 25% of patients will still develop infection postoperatively. Therefore, experts recommend antibiotics for all patients undergoing stent–graft placement in the setting of aorto-enteric fistula, although there is no consensus about the specifics or duration of treatment .
Overall, aorto-enteric fistulae treated by endografts are associated with initial mortality of up to 40%, and 51% of patients will still die of sepsis or recurrent bleeding despite successful surgery. In patients with a more favorable prognosis, conventional open surgical repair would seem to be the preferable option.
Aorto-enteric fistulae are potentially catastrophic causes of gastrointestinal bleeding that are easy to miss if not considered in the differential diagnosis.
Contrast-enhanced CT scanning is the diagnostic modality with the highest sensitivity and specificity for aorto-enteric fistulae.
Early diagnosis enables early intervention by either open surgery or endovascular repair, depending on case-related factors and institutional expertise