A method for introducing a shaped portion of an elongate medical instrument into a body of a subject includes at least partially straightening the shaped portion of the elongate medical instrument. A retention element may be introduced into an interior of the shaped portion of the elongate medical instrument to place and/or maintain the shaped portion in an at least partially straightened configuration. Such straightening may be accomplished without application of external force to an exterior of 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 a retention element that can place and/or maintain a shaped portion of an elongate medical instrument in an at least partially straightened configuration without assistance of external force.
