A device and method for testing for the presence of liquid in a cannula of a medical instrument is described. The device includes a flexible guide member having a first end, a second end and a length extending from the first end to the second end, an elongated member arranged within the flexible guide member, and an absorbent material attached to one of the elongated member. The flexible guide member is inserted into the cannula, the flexible guide member is manipulated to cause the absorbent material to move through the cannula. The absorbent material is analyzed for the presence of liquid.