Rouleaux refers to which phenomenon?

• A. Rupture Of Red Blood Cells
• B. Stacking Of Red Blood Cells
• C. Proliferation Of White Cells
• D. Swelling Of Plasma Proteins

Answer: (B)

Rouleaux is the stacking of red blood cells into coin‑like columns. This happens when plasma proteins, especially fibrinogen or immunoglobulins, are elevated and reduce the negative charge between red blood cells, allowing them to align and adhere in rows rather than stay as single cells. It’s different from true cell clumping caused by antibodies. On a smear you’d see linear stacks of red cells, and clinically it’s often seen with increased plasma protein levels from inflammation, infection, or monoclonal gammopathies. Rouleaux can also raise the erythrocyte sedimentation rate because these stacks settle more rapidly.