A 70-year-old male with a history of diabetes, hypertension, and colon cancer status post a left hemicolectomy 10 years prior is brought to the emergency room from an outside hospital with a contained ruptured abdominal aortic aneurysm (AAA). On arrival he was hypotensive with a heart rate 115 bpm and blood pressure 85/55 mm Hg. He is taken emergently for endovascular aneurysm repair, which was uncomplicated. Postoperatively he is transferred to the surgical intensive care unit and remains stable overnight. Twelve hours later you are called to bedside as the patient is complaining of severe abdominal pain and distension. His vitals are as follows:
Laboratory test results are significant for:
Which is the MOST likely reason for the patients decline?A. Endoleak with bleeding
Correct Answer: D
Colonic ischemia complicates 1% to 3% of elective AAA repairs but up to 10% of ruptured AAA repairs. Physicians must have a high index of suspicion as no laboratory values are pathognomonic for colonic ischemia. Patients commonly develop abdominal pain with fever, elevated lactate, and leukocytosis, while only 30% will have the classic finding of bloody diarrhea. Colonic ischemia can occur in both open and endovascular repairs of AAA. Inferior mesenteric ligation (IMA) in open repairs and coverage of IMA with endovascular repairs likely leads to insufficient blood flow, and prior colon resections likely lead to decreased collaterals between the superior and inferior mesenteric arteries. Atheromatous embolization is also believed to be a culprit in colonic ischemia. Additional risk factors for colonic ischemia include longer operative time, renal insufficiency, and hypotension. Flexible sigmoidoscopy is the diagnostic modality of choice to confirm diagnosis and plan subsequent treatment. Mild forms of colonic ischemia limited to the mucosa may be treated with antibiotics, bowel rest, and serial sigmoidoscopies; however, transmural necrosis requires colectomy and carries a high mortality rate. Retroperitoneal hematoma and endoleak are complications of endovascular surgery and should be kept high on the differential; however, with a stable hemoglobin and signs of colonic ischemia, they are less likely. Ruptured AAAs can result in a large retroperitoneal hematoma before bleeding is controlled and can lead to significant third spacing resulting in abdominal compartment syndrome with signs of hypovolemia or shock; however, this would be unlikely to manifest as fever and leukocytosis.