Apparatus and methods for inhibiting the introduction of air into the body during a percutaneous procedure. The apparatus may include an instrument passage lumen defining a degassing region with a degassing region distal end and a degassing region proximal end, a fluid inlet port at the degassing region distal end, and a fluid outlet port at the degassing region proximal end. So configured, fluid will flow only from the degassing region distal end to the degassing region proximal end.
