Rouleaux formation is promoted by which flow condition?

Rouleaux formation is promoted by which flow condition?

• A. High shear rates
• B. Low shear rates
• C. High hematocrit
• D. Increased temperature

Answer: (B)

Rouleaux formation happens when red blood cells stack together as they flow, and this is favored when the forces tearing cells apart are weak. In slow, low shear flow, there isn’t enough mechanical force to disrupt these cell contacts, so the cells can come into close contact and align into coin-like stacks. Plasma proteins like fibrinogen and globulins can bridge neighboring cells, encouraging this stacking. In contrast, higher shear forces in faster flow actively break up these stacks, preventing rouleaux from forming. Temperature and hematocrit can influence blood viscosity or protein interactions, but the flow condition most directly promoting rouleaux is the low shear environment.

Rouleaux formation happens when red blood cells stack together as they flow, and this is favored when the forces tearing cells apart are weak. In slow, low shear flow, there isn’t enough mechanical force to disrupt these cell contacts, so the cells can come into close contact and align into coin-like stacks. Plasma proteins like fibrinogen and globulins can bridge neighboring cells, encouraging this stacking.

In contrast, higher shear forces in faster flow actively break up these stacks, preventing rouleaux from forming. Temperature and hematocrit can influence blood viscosity or protein interactions, but the flow condition most directly promoting rouleaux is the low shear environment.