Rouleaux is undetectable at which phase?

Rouleaux is undetectable at which phase?

• A. AHG
• B. Room temp
• C. IS
• D. All of the above

Answer: (A)

Rouleaux is a non-specific stacking of red blood cells caused by increased plasma proteins, not by antigen–antibody interactions. It tends to be visible at room temperature or during the immediate-spin phase, where the cells can rearrange into loose columns. During the antiglobulin (AHG) phase, cells are washed to remove unbound proteins and antibodies, and the reaction is read after adding anti-human globulin, which detects only specific IgG-coated cells or complement. Those washing steps and the nature of AHG disrupt or prevent rouleaux from appearing as true agglutination, so rouleaux is not detectable at the AHG phase.

Rouleaux is a non-specific stacking of red blood cells caused by increased plasma proteins, not by antigen–antibody interactions. It tends to be visible at room temperature or during the immediate-spin phase, where the cells can rearrange into loose columns. During the antiglobulin (AHG) phase, cells are washed to remove unbound proteins and antibodies, and the reaction is read after adding anti-human globulin, which detects only specific IgG-coated cells or complement. Those washing steps and the nature of AHG disrupt or prevent rouleaux from appearing as true agglutination, so rouleaux is not detectable at the AHG phase.