Diagnosis of Acute Mesenteric Ischemia in a Patient with End-Stage Renal Disease with Normal Serum Lactate

Acute mesenteric ischemia (AMI) is a life-threatening vascular emergency and a diagnostic challenge for physicians. It represents a group of pathophysiologic processes that have a common end point, that is, bowel infarction, and has a nonspecific clinical picture and a high mortality rate. The most common underlying etiologies are arterial embolism, arterial thrombosis, nonocclusive mesenteric ischemia (NOMI), and mesenteric venous thrombosis. NOMI is caused by prolonged functional vasoconstriction of the visceral arterial vessels, leading to progressive intestinal ischemia, and could be defined by the absence of atherosclerotic thrombotic or embolic occlusion of the mesenteric arteries. The pathophysiology of NOMI remains poorly understood. It can occur in a wide range of critical systemic illnesses associated with hypotension and hypovolemia and in patients on hemodialysis. Elevation of serum lactate may not be present in a significant portion of patients with AMI, which creates an additional obstacle to the prompt diagnosis and often delays treatment. We present a case of a 35-year-old female with HIV and end-stage renal disease on hemodialysis who was admitted for complaints of vague nonspecific abdominal pain. Her initial lactic acid was normal, and due to renal function, she underwent CT of the chest and abdomen without contrast, which only revealed findings consistent with chronic constipation. She later developed vasopressor-dependent hypotension, but her serial lactic acids were all normal. Finally, CT of the abdomen and pelvis was performed with IV contrast, with findings of enterocolitis of the ileum and proximal ascending colon. There was also evidence of pneumatosis involving dilated loops of the small bowel in the lateral mid-abdomen. She underwent an exploratory laparotomy and was found to have gangrene of terminal ileum with associated perforation. Small bowel resection was performed, after which the patient clinically stabilized.