A method for introducing an elongate medical instrument with a shaped portion into the body of a subject includes at least partially straightening the shaped portion from an exterior of the elongate medical instrument. A retention element may then be introduced into an interior of the shaped portion to maintain the shaped portion in an at least partially straightened configuration as the external force is removed from the shaped portion. With the retention element in place, the shaped portion may be introduced to a desired location within a hollow interior of an internal organ. The retention element may then be removed to enable the shaped portion to return to its desired shape. A straightening apparatus includes the retention element, as well as an external element that at least partially straightens the shaped portion of the elongate medical instrument from the outside. A system includes the elongate medical instrument and the straightening apparatus.
