A method of retrieving calculus includes positioning an elongated member in the lumen of the living body, wherein the elongated member includes a sealing member positioned in the lumen of the elongated member and possessing an outer surface in sealing contact with the inner surface of the lumen of the elongated member. The method also involves proximally moving the sealing member while the outer surface of the sealing member is in contact with the inner surface of the lumen in the elongated member to cause fluid and calculus in the living body to pass through the inlet of the elongated member and be introduced into a retrieval space, discharging at least some of the fluid in the retrieval space out of the retrieval space by way of an outlet, and withdrawing the elongated member from the living body while the calculus in the retrieval space remains in the retrieval space.