Method and apparatus for uterine cavity length measurement

1. A uterine cavity length measuring device, comprising:

a first elongate member including a lumen and a plurality of apertures extending between the lumen and an exterior surface of the first elongate member, the first elongate member configured for insertion through a cervical canal with at least a portion of the first elongate member extending into a uterine cavity; and

a second elongate member including a lumen, a distal end, and at least one aperture located at the distal end extending from the lumen of the second elongate member to an exterior surface of the second elongate member, where the second elongate member is positioned within and is configured to move within the lumen of the first elongate member;

wherein the first elongate member and second elongate member provide a fluid path from a proximal end of the lumen in the second elongate member, through the lumen in the second elongate member to the at least one aperture located at the distal end of the second elongate member and to at least one of the plurality of apertures in the first elongate member, the first elongate member and second elongate member being configured such that fluid flow through the fluid path and into the uterine cavity is permitted when the distal end of the second elongate member is positioned within a portion of the first elongate member that is positioned within the uterine cavity and such that fluid flow through the fluid path is restricted when the distal end of the second elongate member is positioned within a portion of the first elongate member that is positioned within the cervical canal.

2. The uterine cavity length measuring device of claim 1 , further comprising:

a fluid flow sensor configured to indicate a change in fluid flow through the fluid path.

3. The uterine cavity length measuring device of claim 1 , where a distal end of the first elongate member includes an atraumatic tip.

4. The uterine cavity length measuring device of claim 1 , where the distal end of the second elongate member further comprises:

a first ring positioned distally of the at least one aperture and configured to provide a substantially airtight seal between the distal end of the second elongate member and an interior surface of the first elongate member; and

a second ring positioned proximally of the at least one aperture and configured to provide a substantially airtight seal between the distal end of the second elongate member and an interior surface of the first elongate member.

5. The uterine cavity length measuring device of claim 1 , where the first elongate member further comprises:

one or more exhaust lumens extending from approximately a proximal end to a distal end of the first elongate member; and

one or more exhaust holes, each exhaust hole extending between the exterior surface of the first elongate member and at least one of the one or more exhaust lumens.

6. The uterine cavity length measuring device of claim 1 , further comprising:

an air input port coupled to a proximal end of the second elongate member.

7. The uterine cavity length measuring device of claim 6 , further comprising:

a fluid flow sensor positioned at the proximal end of the second elongate member and fluidly coupled to the air input port.

8. The uterine cavity length measuring device of claim 7 , where the fluid flow sensor comprises a paddlewheel.

9. The uterine cavity length measuring device of claim 1 , further comprising:

graduations marked on at least a portion of the length of the second elongate member configured to indicate a measurement of a length of the uterine cavity.

10. The uterine cavity length measuring device of claim 1 , further comprising:

graduations marked on at least a portion of the length of the first elongate member configured to indicate a measurement of from an external cervical os to a fundus of the uterus.

11. The uterine cavity length measuring device of claim 1 , where the fluid is air.

12. A uterine cavity length measuring device comprising:

a first elongate member including a lumen, the first elongate member configured for insertion through a cervical canal with at least a portion of the first elongate member extending into a uterine cavity;

a second elongate member including a lumen, where the second elongate member is positioned within the lumen of the first elongate member and is configured to move within the lumen of the first elongate member; and

a fluid flow sensor configured to indicate a change in fluid flow through the lumen in the second elongate member, where the fluid flow decreases when a distal end of the second elongate member is positioned within a portion of the first elongate member that is positioned within the cervical canal as compared to the fluid flow when a distal end of the second elongate member is positioned within a portion of the first elongate member that is positioned within the uterine cavity.

13. A uterine cavity length measuring device, comprising:

a first elongate member including a lumen, the first elongate member configured for insertion through a cervical canal with at least a portion of the first elongate member extending into a uterine cavity;

a second elongate member including a lumen, where the second elongate member is positioned within the lumen of the first elongate member and is configured to move within the lumen of the first elongate member;

an end cap connected to the distal end of the first elongate member, the end cap being in a closed position when the first elongate member is inserted into the uterine cavity and switching into an open position when a force applied to a distal tip of the end cap by uterine tissue exceeds a threshold force, where a surface area of the end cap projected onto a plane substantially perpendicular to the longitudinal axis of the first elongate member is enlarged in the open position as compared to in the closed position, and where the open position resists penetration of the end cap into uterine tissue; and

a fluid flow sensor configured to indicate a change in fluid flow through the lumen in the second elongate member.

14. The uterine cavity length measurement device of claim 13 , wherein the end cap includes one or more fin members, where the fin members are positioned along a longitudinal axis of the first elongate member when the end cap is in the closed position and deploy laterally from the longitudinal axis when switching into the open position.

15. The uterine cavity length measurement device of claim 13 , further comprising:

a deployment mechanism, configured to switch the end cap from the closed position to the open position upon a force on the distal tip of the end cap exceeding the threshold force.

16. The uterine cavity length measurement device of claim 15 , wherein:

the end cap includes one or more fin members, where the fin members are positioned along a longitudinal axis of the first elongate member when the end cap is in a closed position and deploy laterally from the longitudinal axis when switching into the open position;

the first elongate member includes a rod connected to the distal tip of the end cap; and

the deployment mechanism includes a spring positioned about the first elongate member, the spring preloaded to exert the threshold force on a first face of a retainer connected to the rod, where the threshold force exerted by the spring prevents the rod from translating in a direction away from the end cap and where the retainer includes a second face abutting a housing preventing translation of the rod in a direction toward the end cap,

wherein when a force on the distal end of the end cap by uterine tissue exceeds the threshold force, the rod translates axially compressing the spring and thereby translating the distal end of the end cap causing the one or more fin members to deploy laterally switching the end cap into the open position.

17. The uterine cavity length measuring device of claim 13 , further comprising;

an indicator configured to provide an indication to a user when the end cap has switched from the closed to the open position.