Final answer:
In a femoro-femoral bypass, a Balfour retractor is used to maintain visibility and access to the surgical area.
Step-by-step explanation:
The retractor used during a femoro-femoral bypass is typically the Balfour retractor. This retractor is designed to hold open the incision, providing better visibility and access to the surgical site. The Balfour retractor has adjustable side blades that can accommodate different incision sizes and is commonly used in abdominal and vascular surgery, such as a femoro-femoral bypass.