Variable Diameter Surgical Drains and Sheaths

A system comprising:

• an elongated structure comprising:
• a distal end configured to be placed in an body cavity and change in diameter when present in the body cavity from a first diameter to a second diameter that is smaller than the first diameter, wherein the change in diameter is mediated by a diameter-varying element;
• a proximal end configured to be outside of the body when the distal end is present in the body cavity;
• a lumen configured to drain a substance from the body cavity;
• a syringe attached to the lumen;
• and
• a drainage apparatus.

A method of draining a body cavity in a body, the method comprising:

• positioning a distal end of an elongated structure in a body cavity, wherein the elongated structure comprises:
• a distal end configured to be placed in a body cavity and change in diameter when present in the body cavity from a first diameter to a second diameter that is smaller than the first diameter, wherein the change in diameter is mediated by a diameter-varying element;
• a proximal end configured to be outside of the body when the distal end is present in the body cavity;
• and
• a lumen configured to drain a substance from the body cavity;
• draining a substance from the body cavity via the positioned surgical drain;
• decreasing the diameter of the distal end of the elongated structure prior to removal of the elongated structure;
• and
• removing the distal end of the elongated structure from the body cavity,
• wherein the body cavity is an abdominal body cavity or a cavity in an extremity of the body.