S1960 Acute Pseudomembranous Colitis, Microangiopathic Hemolytic Anemia, and Renal Injury After Pericardiectomy

Abstract

Introduction: Acute colonic ischemia following surgery is usually a result of colonic hypoperfusion, particularly in watershed regions; however, it is critical to maintain a broad differential diagnosis for alternate etiologies. Case description/methods: A 57-year-old man with lupus on hydroxychloroquine and prednisone underwent elective pericardiectomy for medically refractory constrictive pericarditis. On post-operative day (POD) 3, he developed abdominal pain, nausea, and non-bloody diarrhea. Hematochezia started on POD 4. Computed tomography showed rectosigmoid thickening and perirectal fat stranding (Figure 1A). Sigmoidoscopy revealed edematous, ulcerated, and discolored mucosa from the anal verge to 30 cm proximally that abruptly normalized thereafter (Figure 1B). Sigmoid histology showed lamina propria hemorrhage with crypt withering and focal pseudomembranes (Figure 1C). Clostridioides difficile testing was negative. Colonic ischemia was favored. Given persistent leukocytosis and low fevers, antibiotics were started. From POD 4 to 8, platelets dropped from 142 to 11 × 109/L, and creatinine rose from 1.1 to 2.0 mg/dL (Figure 2). On POD 6, labs showed lactate dehydrogenase 1,107 U/L, indirect bilirubin 2.7 mg/dL, and undetectable haptoglobin, with hemoglobin dropping from 14.0 to 12.9 g/dL from POD 7 to 8. Peripheral smear on POD 8 showed schistocytes (Figure 3). Serum ADAMTS-13, complement levels, and heparin-induced thrombocytopenia panels were normal. Stool PCR detected shiga-toxin producing E. coli and shiga toxin 2, and stool cultures did not grow the 0157:H7 E. coli strain. Antibiotics were stopped due to the diagnosis of shiga-toxin induced hemolytic uremic syndrome (ST-HUS). The hemolysis, thrombocytopenia, and renal injury resolved after one week of supportive measures. Discussion: Infection by shiga-toxin producing E. coli (STEC), especially with shiga toxin 2 (which disrupts protein synthesis, causing apoptosis), presents with hemorrhagic colitis in 80% of cases and ST-HUS in up to 15% of cases. STEC is often acquired from contaminated food/ water. In this case, a hamburger from an external vendor was the suspected source. After a 3-day incubation period, STEC classically presents with abdominal pain and non-bloody diarrhea, followed by bloody diarrhea 1-3 days later. If it occurs, ST-HUS presents 1-2 weeks later from thrombotic microangiopathy. Antibiotics are linked to shiga toxin production by the encoding bacteriophage in the STEC chromosome.Figure 1.: Acute pseudomembranous colitis. A) Rectosigmoid wall thickening (green arrow) and perirectal fat stranding. B) Rectosigmoid colon was edematous, cyanotic, ulcerated, with luminal narrowing by flexible sigmoidoscopy. There was an abrupt transition to normal sigmoid mucosa at 30 cm from anal verge (not shown). C) Pathologic specimens from sigmoid colon showed crypt withering (blue arrow), lamina propria hemorrhage (orange arrow), and pseudomembrane (yellow arrow).Figure 2.: Clinical course of shiga-toxin induced hemolytic uremic syndrome (ST-HUS). Non-bloody diarrhea started on POD 3, followed by bloody diarrhea on POD 4. The patient’s thrombotic microangiopathy, signified by reduction in platelets and renal injury, began 3-4 days later, illustrating the characteristic delay from diarrhea onset and thrombotic microangiopathy in ST-HUS.Figure 3.: Peripheral smear. Peripheral smear was notable for schistocytes (blue arrow), suggestive of hemolysis, and markedly diminished number of platelets (green arrow). The combination of these features was consistent with thrombotic microangiopathy.