What does rouleaux formation on a blood smear indicate about the red blood cells?

Rouleaux formation is characterized by red blood cells clumping together in long chains or stacks, resembling a pile of coins. This phenomenon typically occurs due to an increase in plasma proteins, such as fibrinogen or globulins, which leads to a change in the charge on the red blood cell membranes, promoting aggregation.

The presence of rouleaux can be indicative of conditions affecting the plasma protein levels, such as inflammation, infections, or certain malignancies. It's important to recognize that while this agglomeration indicates a change in the behavior and interaction of red blood cells in the blood, it does not imply that the cells themselves have abnormal size, are immature, or are undergoing hemolysis. Thus, the accurate interpretation of rouleaux formation is essential in clinical diagnosis and hematological evaluation.