A 3-year-old boy develops pallor and oliguria five days after an episode of bloody diarrhea. Platelet count is 45,000/microL, creatinine 2.1 mg/dL, LDH markedly elevated. Which finding on peripheral smear confirms the mechanism of his anemia?

• A Spherocytes lacking central pallor
• B Fragmented helmet cells and triangular cells ✓
• C Sickle shaped elongated erythrocytes
• D Teardrop cells with nucleated red cells

Explanation

Shiga toxin associated hemolytic uremic syndrome injures endothelium, and red cells are sheared by fibrin strands in narrowed microvessels, producing schistocytes including helmet and triangular fragments. This microangiopathic process combines intravascular hemolysis, thrombocytopenia, and renal failure. Spherocytes indicate membrane loss from antibody or hereditary defects, sickled cells reflect polymerized hemoglobin S, and teardrop cells with nucleated red cells suggest a bone marrow infiltrative process.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.