Rouleaux formation correlates with an increased concentration of serum monoclonal proteins. Rouleaux may be seen as an artifact in the thicker portions of blood smears.

• The addition of a drop of saline to the blood smear will serve to disperse any artifactual rouleaux formation.
• The presence of rouleaux formation or RBC agglutination may result in a falsely decreased electronic red blood count and falsely increased MCV, as these clusters may be read as one cell.