What is the effect of ultrafiltration in the dialysis process?

In the dialysis process, ultrafiltration primarily serves to remove excess fluid from the blood, which is critical for patients with kidney failure or those undergoing dialysis. This process utilizes a pressure gradient to pull excess fluid through the dialysis membrane, effectively reducing blood volume and helping to prevent complications associated with fluid overload.

While ultrafiltration is primarily focused on fluid removal, it also contributes to the removal of certain small molecular weight toxins within that fluid. This is because the fluid being removed typically contains both excess water and waste products. However, the primary function that ultrafiltration is known for is the management of fluid balance.

Therefore, the correct answer highlights the important role of ultrafiltration in both functions — removing excess fluid and aiding in the removal of toxins — thus making it accurate to state that both aspects are covered by this process in the context of dialysis.