A 56-year-old man with a recent diagnosis of acute myeloid leukemia was admitted 10 days ago for induction chemotherapy with cytarabine and anthracycline. Over the past 24 hours he has developed worsening abdominal pain and distension along with a fever of 38.8°C and watery diarrhea. CT shows bowel wall thickening of >10 mm in both the small and large intestine.
Which of the following statements is true regarding this patient’s likely diagnosis?
A. Enteral feeding helps to decrease complicationsCorrect Answer: B
Neutropenic enterocolitis (NE), also known as necrotizing enterocolitis or ileocecal syndrome, involves inflammation and necrosis of the gut in a neutropenic patient caused by an invasive infection. Patients with an absolute neutrophil count (ANC) <1,500 cells/µL are at risk, although generally the ANC is much lower. Any segment of the gastrointestinal (GI) tract may be involved. Patients being treated for acute leukemia appear to be at highest risk, but it has been documented in most neutropenic and immunocompromised populations. The lack of neutrophils allows overgrowth of gut organisms, particularly gram-negative bacilli. One proposed mechanism of NE is GI distension and impaired perfusion leading to decreased mucosal integrity, allowing entry of these organisms into the bowel wall. Bowel wall integrity can also be compromised by chemotherapy. This can lead to ischemic necrosis, perforation, and/or peritonitis. Signs include lower abdominal tenderness and distension, watery diarrhea, and occasionally GI bleeding. Bacteremia is common and many patients will present with sepsis. Gram-negative bacteria are the usual culprit, but other bacteria and fungi are not uncommon. Most experts suggest that the combination of abdominal pain and fever in a neutropenic patient warrants treatment for presumptive NE with imaging used to help confirm the diagnosis. CT often shows bowel wall thickening and edema, which is also common in C. diff colitis; pneumatosis intestinalis is more specific for either NE or ischemia. Other CT findings can include nonspecific ileus, phlegmon, pericecal inflammation, mesenteric stranding, free air, and extraluminal fluid collections. Histologic examination is the gold standard for diagnosis, but due to the risk of perforation and bleeding from colonoscopy in neutropenic, thrombocytopenic patients, tissue samples are rarely obtained. Colonoscopy can show thickened, edematous, hemorrhagic bowel with diffuse ischemic colitis present in the majority of cases. Treatment includes broad-spectrum antibiotics, bowel rest, nasogastric suction, parenteral nutrition, and IV fluids. Myeloid growth factors may also improve outcomes. Surgery is reserved for those with evidence of perforation, peritonitis, gangrenous bowel, or refractory GI hemorrhage. In fact, all febrile neutropenic patients should be started on empiric broad-spectrum antibiotics.
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