DEVICE FOR INTRAMURAL ACCESS TO THE GASTROINTESTINAL TRACT - Patent application

Abstract

A gastrointestinal intraluminal device (10) for deploying markers (42, 44, 46) in the gastrointestinal tract of a patient, the device being optionally as defined in any of the preceding claims, comprising a flexible tube (12) retrievably insertable into the gastrointestinal tract and capable of following the tortuous path of the small intestine and introduceable into the gastrointestinal tract of a patient, the tube being in an at least partially invaginated state, the tube having a fixed end (12d) and a movable lumen (14), the tube being adapted to expand or contract the fixed end by expanding an expandable region (16) of the tube about the lumen. The device comprises a flexible tube that is extendable within the tube without substantial movement, and whereby expansion causes a distal-most invaginated material (12c) to evert outwardly, whereby the everted material extends the deployed length of the tube distally along the path of the gastrointestinal tract, and whereby the luminal invaginated material (12b) is retracted distally within the deployed tube to provide a distal extension, and a plurality of marker elements (42, 44, 46) detectable by fluoroscopic imaging, optionally at least one of the marker elements being deployable from a collapsed state to an expanded state.

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates to the field of intraluminal access to a vessel or lumen within a patient's body, particularly, but not exclusively, the gastrointestinal tract. Some embodiments relate to access to assist in the creation of an anastomosis in the gastrointestinal tract or other body tract. [Background technology]

[0002] 2. Background of the Invention An anastomosis is a surgical cross connection or bridge between two different sections of a body conduit lumen. The gastrointestinal tract is the luminal pathway in the body from the esophagus to the anus. Anastomoses formed along or anywhere in the gastrointestinal tract are a form of therapy used to treat digestion-related problems such as diabetes, obesity, bowel disease and blockages. Anastomoses can be used to bypass parts of the gastrointestinal tract, such as parts of the small intestine, to avoid sensitive areas or to affect or reduce the absorption of nutrients. Summary of the Invention [Problem to be solved by the invention]

[0003] Currently, laparotomy provides the most comprehensive access to internal anatomical structures for creating an anastomosis. However, laparotomy is highly invasive and not suitable for many patients and conditions to be treated. Although minimally invasive procedures have been proposed, significant challenges remain in creating anastomoses equally effectively through minimally invasive procedures, especially endoluminally. In endoluminal procedures, one or more instruments are introduced into the body, primarily through the body tract where the anastomosis is to be performed. Current endoluminal techniques are best suited for relatively shallow anastomosis procedures in body tracts. This limits the versatility of the procedure for, for example, the small intestine, which can have a length of up to six or seven meters in most adults and is folded to follow a very tortuous path in the abdomen. [Means for solving the problem]

[0004] Summary of the Invention It would be desirable to address and / or alleviate one or more of the above problems.

[0005] Aspects of the invention are defined in the claims. Additionally or alternatively, an aspect of the present invention provides an intraluminal gastrointestinal device for assisting in the creation of an anastomosis between spaced apart locations within a patient's gastrointestinal tract, the device being or being retrievably insertable into the gastrointestinal tract and capable of following the tortuous path of the small intestine.

[0006] The device comprises a flexible tube introduceable into the gastrointestinal tract of a patient, the tube being in an at least partially invaginated state, the tube having a fixed end and a movable lumen. The tube is extendable within the tract without substantially moving the fixed end by expanding an expandable region of the tube about the lumen. The expansion everts a distal-most invaginated material outwardly, whereby the everted material extends a deployed length of the tube distally along a path of the gastrointestinal tract. The invaginated material of the lumen is retracted distally within the deployed tube to provide a distal extension.

[0007] Such an arrangement can provide significant advantages over conventional catheter or endoscopic devices.

[0008] One advantage is the reduction of frictional sliding contact between the device and the gastrointestinal tissue. The tube has a fixed end that is generally immobile. Extension of the deployed length of the tube is accomplished by everting the invaginating material from within the tube, rather than advancing the outside of the tube. As a result, there is little or no frictional sliding resistance as the tube advances, even deep in the tube, and even through the tortuous turns of, for example, the small intestine. In contrast, a conventional catheter or endoscope comprises a tubular shaft having an outer surface that slides against the tissue wall as it advances. The frictional resistance increases as the shaft advances through the tube, contacting progressively more tissue. The frictional resistance also increases with the tortuosity of the tube, which can limit the depth to which some conventional devices can be navigated, for example, in the small intestine.

[0009] Another advantage is that the tube is highly conformable and can be easily advanced through, for example, the folded, tortuous turns of the small intestine. In contrast, conventional catheters or endoscopes have shafts that are more resistant to bending, which can limit the depth to which some conventional devices can be navigated.

[0010] In some embodiments, the tube can be retrieved by retracting the inner portion of the tube, optionally the lumen, proximally, causing the tube to collapse and / or invaginate from its most distal region. Such removal techniques can achieve the same advantages during removal as those described above for introduction.

[0011] When preparing one or more target sites for anastomosis, the present invention can greatly aid in measuring distances between specific points in the gastrointestinal tract to ensure that specific distances within the tract are bypassed. Additionally or alternatively, locations can be marked to facilitate preparation and formation of the anastomosis.

[0012] In some embodiments, the tube comprises at least one marker element for marking a predetermined length or location along the deployed portion of the tube. Optionally, the marker element is radiopaque to facilitate detection by fluoroscopic imaging. Additionally or alternatively, the marker element may be expandable from a collapsed configuration to an expanded configuration.

[0013] In addition to or instead of marker elements on the tube, the device may further comprise a guidewire insertable through the lumen toward the distal end of the tube, The guidewire may be configured to remain in place when the tube is withdrawn.

[0014] In some embodiments, the guidewire carries at least one marker element for marking a predetermined length or location along the guidewire. Optionally, the marker element is radiopaque to facilitate detection by fluoroscopic imaging.

[0015] In some embodiments, the marker element is expandable from a collapsed state on the guidewire to an expanded state that is laterally larger than the main portion of the guidewire. The marker element may comprise (i) an anchor for expansion against tissue of the gastrointestinal tract, and / or (ii) an expandable cage.

[0016] Even if at least one marker element is implemented on the tube and / or guidewire, multiple marker elements may be provided. The first and second marker elements may be spaced apart by a predetermined distance. Additionally or alternatively, at least some of the marker elements are spaced apart by a uniform repeating separation.

[0017] Additionally or alternatively to any of the above, in some embodiments the lumen comprises a non-evertable region that is pulled distally within the tube as the tube elongates, optionally until the non-evertable region reaches a distal-most portion of the tube. The non-evertable region may define a working channel for inserting a guidewire and / or one or more instruments.

[0018] A second aspect of the invention, optionally in combination with any of the features of the first aspect, may provide an intraluminal gastrointestinal device for deploying a marker in the gastrointestinal tract of a patient, the device being retrievably insertable into the gastrointestinal tract and capable of following the tortuous path of the small intestine. The device comprises: a flexible tube introduceable into a patient's gastrointestinal tract, the tube being in an at least partially invaginated state, the tube having a fixed end and a movable lumen, the tube being extendable within the tract without substantial movement of the fixed end by expanding an expandable region of the tube about the lumen, the expansion everting a distal-most invaginated material outwardly, whereby the everted material extends a deployed length of the tube distally along a path of the gastrointestinal tract, and the invaginated material of the lumen is retracted distally within the expanded tube to provide a distal extension; a plurality of marker elements detectable by fluoroscopic imaging, optionally at least one of the marker elements being deployable from a folded state to an expanded state; It may comprise:

[0019] At least one of the marker elements may be carried by the tube. Additionally or alternatively, the device may further comprise a guidewire insertable through the lumen of the tube, the guidewire carrying at least one of the marker elements.

[0020] A third aspect of the invention provides a method of introducing a device into the gastrointestinal tract of a patient. The device may optionally include any of the features described in the first and second aspects. Additionally or alternatively, the device may comprise a flexible tube introduceable into the gastrointestinal tract of a patient, the tube being at least partially invaginated, the tube having a fixed end and a movable lumen.

[0021] The method includes expanding an expandable region of the tube about the lumen, the expansion everting the distal-most invaginated material outwardly, whereby the everted material extends the deployed length of the tube distally along the path of the gastrointestinal tract, and the luminal invaginated material is retracted distally within the expanded tube to provide a distal extension whereby the tube is extendable within the tract without substantial movement of the fixed end.

[0022] In some embodiments, the method includes or further includes deploying at least one marker element to indicate the predetermined length or position. The deploying step may optionally occur as part of and / or as a result of the expansion of the tube as it gradually stretches. Additionally or alternatively, the deploying step may be an additional step to or include the expansion of the tube.

[0023] The marker element may optionally be radiopaque to facilitate identification by medical imaging techniques.Deploying the marker element may include causing the marker element to expand.

[0024] In some embodiments, the method includes or further includes deploying at least a second marker element.

[0025] Another aspect of the invention provides a method for identifying a target location within a gastrointestinal tract of a patient, the method comprising: - providing an apparatus comprising a flexible tube introduceable into the gastrointestinal tract of a patient, the tube being at least partially invaginated, the tube having a fixed end and a movable lumen, the apparatus optionally according to the first and / or second aspect above; expanding an expandable region of the tube about the lumen, the expansion everting the distal-most invaginated material outwardly, whereby the everted material extends the deployed length of the tube distally along the path of the gastrointestinal tract, and the luminal invaginated material is retracted distally within the expanded tube to provide a distal extension; deploying at least one marker element for identifying the target site; Includes.

[0026] Another aspect of the invention provides a method for measuring distance within a gastrointestinal tract of a patient, the method comprising: - providing an apparatus comprising a flexible tube introduceable into the gastrointestinal tract of a patient, the tube being at least partially invaginated, the tube having a fixed end and a movable lumen, the apparatus optionally according to the first and / or second aspect above; expanding an expandable region of the tube about the lumen, the expansion everting the distal-most invaginated material outwardly, whereby the everted material extends the deployed length of the tube distally along the path of the gastrointestinal tract, and the luminal invaginated material is retracted distally within the expanded tube to provide a distal extension; deploying at least a first marker element and a second marker element having a predetermined spacing; Includes.

[0027] In any of the above embodiments, the device may be introduced or configured to be introduced into the patient's intestine through the patient's mouth and / or stomach.

[0028] Another aspect of the invention extends the use of the invention for use with other vessels within a patient's body. An apparatus may be provided for assisting in the formation of an anastomosis between spaced apart locations within a patient's body vessel, the apparatus being retrievably insertable within the vessel (e.g., intraluminally) and capable of following the vessel's curved path. The apparatus may comprise a flexible tube introduceable within the patient's vessel, the tube being in an at least partially invaginated state, the tube having a fixed end and a movable lumen, the tube being extendable within the vessel without substantial movement of the fixed end by expanding an expandable region of the tube about the lumen, the expansion everting a distal-most invaginated material outwardly, whereby the everted material extends the deployed length of the tube distally along the path of the vessel, and the invaginated material of the lumen being retracted distally within the deployed tube to provide a distal extension.

[0029] Optionally, this aspect may use any of the features described for the previous aspects. In any of the above embodiments, a distal direction will be understood to be a direction extending deeper along a body canal or duct, relative to the point of entry of the device into the body canal or duct, and / or relative to a fixed end of the tube, and / or relative to an operator of the device.

[0030] Although certain ideas, features and advantages have been emphasized above and in the appended claims, protection is claimed for any novel feature or idea described in this specification and / or shown in the drawings, whether or not emphasis is given. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an invagination tube device. [Diagram 2] 1 is a schematic cross-sectional view illustrating the stretching of an invaginating tube device to increase its deployed length. [Diagram 3] FIG. 2 is a schematic cross-sectional view showing full deployment of the tube. [Figure 4] FIG. 1 is a schematic cross-sectional view showing the introduction of a tube device into the gastrointestinal tract. [Diagram 5] FIG. 13 is a schematic cross-sectional view showing the deployment of a tube into the small intestine. [Figure 6] FIG. 1 is a schematic cross-sectional view showing a guidewire positioned in the small intestine by introduction through an deployed tube. [Figure 7] 13 is a schematic cross-sectional view showing a further example of a guidewire having an expandable anchor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Non-limiting embodiments will now be described, by way of example, with reference to the accompanying drawings, in which like reference numbers denote the same or equivalent features, whether or not explicitly described in detail, and in which:

[0033] 1-3 illustrate the deployment principle of one embodiment of a gastrointestinal device 10 that is configured to assist in the creation of an anastomosis between spaced apart locations within a patient's gastrointestinal tract and that is capable of following the tortuous path of the small intestine.

[0034] The device comprises a flexible tube 12 introduceable into the gastrointestinal tract of a patient, the tube being in an at least partially invaginated state, the tube 12 including an outer everted material 12a, an invaginating material 12b defining a lumen 14, a distal-most invaginating material 12c at the distal tip of the tube and in communication with the everted material 12a and the invaginating material 12b, and a normally fixed end 12d.

[0035] In use, the tube 12 can be stretched in the gastrointestinal tract by applying an inflation pressure around the lumen 12b within the expandable region 16 of the tube 12. Any suitable inflation fluid can be used, e.g., a liquid (such as saline) or a gas (such as air). With reference to FIG. 2, inflation causes the distal-most invaginated material 12c to evert outwardly (represented by arrow 18), whereby the everted material extends the deployed length of the tube distally. The invaginated material 12b of the lumen 14 is retracted distally to provide a distal extension (represented by arrow 20). The invaginated material 12b includes sufficient excess material that allows the tube to adopt an expanded, everted diameter without substantial elastic stretch. The excess material may be loosely folded in the lumen 14.

[0036] Optionally, the section of the lumen may further comprise a non-evertable region 12e, e.g., a region having insufficient lateral dimension to evert outwardly. When the non-evertable region reaches the distal-most portion of the tube, further distal extension stops. In other words, the tube 12 has reached a fully deployed state (FIG. 3).

[0037] An advantage of the deployment technique for tube 12 is that the tube can extend into the gastrointestinal tract with little or substantially no frictional resistance. The exterior of tube 12 does not substantially slide against surrounding body tissue, but instead remains fixed relative to fixed end 12d. Also, the absence of a central support or spine allows tube 12 to be very flexible and conformable, allowing it to extend along and around the bends of the unpredictable and tortuous path of the small intestine, for example.

[0038] The device may optionally further comprise a sheath 22 that carries the tube 12. The fixed end 12d of the tube 12 may, for example, be near or attached to a distal region 22a of the sheath 22, with the adjacent invaginated tubing 12b contained within the sheath 22 and extending proximally relative to the distal region 22a of the sheath 22. The sheath 22 may facilitate initial introduction of the tube 12 into the gastrointestinal tract and, in combination with and / or collectively with the tube, may define a portion of a conduit passageway.

[0039] 4 to 7 show an example of the operation of the device 10. FIG. 4, the device 10 is introduced into the patient's gastrointestinal tract 30, for example via the mouth and esophagus, through the stomach 32 and towards the small intestine 34. Navigating the device 10 through the esophagus and stomach 32 is relatively straightforward as the gastrointestinal tract is relatively large and non-tortuous. This portion of the introduction may be performed by the sheath 22, which may have a length that extends to approximately the fundus of the stomach 32. At this initial stage, the invaginated tube 12 is at least partially contained within the sheath 22 and extends proximally within the sheath 22. The tube 12 does not protrude substantially beyond the distal end region 22a of the sheath 22, and only a small distal-most invaginated region 12c of the tube is shown in FIG.

[0040] 5, tube 12 is extended into small intestine 34 by expanding tube 12 to evert the distal-most invaginated material, as described above. The deployed length of tube 12 extends as more invaginated material everts from the tip, until tube 12 reaches its fully deployed state shown in FIG. 5. The lumen formed by the non-evertable portion of material defines a working channel 38 that extends from the distal end of tube 12 to the distal end 22a of sheath 22, with the working channel extending further within sheath 22 to the sheath proximal end (not shown), and optionally outside the body.

[0041] 6, device 10 further comprises a guidewire 40 insertable through working channel 38. Tube 12 can then be removed by pulling on the tube proximal end to collapse the tube inward from its distal end. Guidewire 40 may remain in place within the small intestine, as shown in FIG. 6. Optionally, sheath 22 may remain within the esophagus and stomach 32.

[0042] When preparing one or more target sites for anastomosis, the guidewire 40 can greatly aid in measuring distances between specific points in the gastrointestinal tract 30 to ensure that a specific distance in the tract is bypassed. For example, the guidewire may carry at least one, optionally at least two, and optionally more than two marker elements 42 for marking a predetermined length or location along the guidewire 40. The marker elements are preferably radiopaque to facilitate detection by fluoroscopic imaging. The marker elements 42 may comprise a different material (e.g., more radiopaque) than the guidewire 40 and / or the marker elements 42 may be larger so as to be identifiable. In the illustrated example, the marker elements 42 are approximately uniformly distributed along the length of the guidewire 40 and have a uniform separation between adjacent marker elements 42 to enable distances to be measured by counting the marker elements 42.

[0043] In addition to or instead of the marker element 42, one or more deployable marker elements 44 may be provided on the guidewire 40. For example, the deployable marker element 44 may be in the form of a deployable anchor or cage. The deployable marker element 44 may be self-expandable, for example, when the tube 12 is removed from the guidewire 40, or the deployable marker element 44 may be manually deployed by an operator using a remote deployment mechanism (not shown). First and second deployable marker elements 44 are shown and are set a predetermined distance apart to identify the location where they will be joined together by the anastomosis and to achieve a predetermined bypass length. The deployable marker elements 44 may be made of a radiopaque material to facilitate detection by fluoroscopy.

[0044] Regardless of whether a guidewire 40 is used, one or more marker elements 46 may optionally be disposed on the tube 12. The or each marker element 46 is collapsible and expandable by the material of the tube, and expands outward when the portion of the tube 12 carrying the marker element 46 everts outward to increase the deployed length of the tube 12. The or each marker element 46 may include a radiopaque material to facilitate detection by fluoroscopy. The multiple marker elements 46 may define a measurement boundary in a manner similar to marker element 42 described above, or may define a predetermined location marker similar to marker element 44 described above.

[0045] While the above embodiments have been described in the context of a gastrointestinal endoluminal device, and the embodiments provide significant advantages in facilitating access deep within the small intestine and in deploying marker elements to assist in anastomosis creation, it will be appreciated that these concepts may be more broadly applied to other body lumen, particularly those that follow curved or tortuous paths.

[0046] It will be understood that the foregoing is merely illustrative of exemplary embodiments of the invention, and that many modifications and equivalents may be used within the principles of the invention.

Claims

**Claim 1** A gastrointestinal tract luminal device (10) for assisting in the formation of an anastomosis between spaced-apart locations within a patient's gastrointestinal tract, the device being insertable into the gastrointestinal tract in a retrievable manner and capable of following a tortuous path of the small intestine, a flexible tube (12) introducible into a patient's gastrointestinal tract, the flexible tube being at least partially in a collapsed state, the flexible tube having a fixed end (12d) and a movable lumen (14), the flexible tube being extensible within the lumen by expanding an expandable region (16) of the flexible tube around the movable lumen without substantial movement of the fixed end, the expansion turning the most distal collapsed material (12c) outwardly inside out, the inside-out material extending the deployed length of the flexible tube distally along the path of the gastrointestinal tract, and the collapsed material (12b) of the movable lumen being drawn distally within the deployed tube to provide a distal extension, flexible tube (12) comprising a gastrointestinal tract luminal device (10). **Claim 2** The device according to claim 1, wherein the flexible tube (12) is retrievable by pulling proximally an inner portion of the flexible tube, optionally of the movable lumen, to fold and / or collapse the flexible tube from its most distal region. **Claim 3** The device according to claim 1, further comprising a sheath (22) coupled to the fixed end (12d) of the flexible tube to facilitate introduction of the device into the gastrointestinal tract. **Claim 4** The device according to claim 1, wherein the flexible tube (12) comprises at least one marker element (46) for marking a predetermined length or position along the deployed portion of the flexible tube. **Claim 5** The device according to claim 4, wherein the marker element is radiopaque to facilitate detection by fluoroscopic imaging. **Claim 6** The device according to claim 4, wherein the marker element (46) is expandable from a folded configuration to an expanded configuration. **Claim 7** The movable lumen is a non-invertible region (12e), and the non-invertible region (12e) is optionally pulled distally within the tube as the flexible tube extends until the non-invertible region (12e) reaches the most distal portion of the flexible tube. The non-invertible region (12e) defines a working channel (38) for inserting a guide wire and / or one or more instruments. The device according to claim 1.

8. The device according to claim 1, further comprising a guide wire (40) insertable through the movable lumen towards the distal end of the flexible tube, and optionally, the guide wire is configured to remain in a predetermined position when the flexible tube is retracted.

9. The device according to claim 8, wherein the guide wire carries at least one marker element (42, 44) for marking a predetermined length or position along the guide wire.

10. The device according to claim 9, wherein the marker element is radiopaque to facilitate detection by fluoroscopic imaging.

11. The device according to claim 9, wherein the marker element (44) is expandable from a folded state on the guide wire to an expanded state that is laterally larger than the main portion of the guide wire.

12. The device according to claim 11, wherein the marker element (44) comprises (i) an anchor for expanding against gastrointestinal tissue and / or (ii) an expandable cage.

13. The device according to claim 4, comprising a plurality of the marker elements (42, 44, 46).

14. The device according to claim 13, wherein the first and second marker elements are spaced apart by a predetermined distance.

15. The device according to claim 13, wherein at least some of the markers are spaced apart by uniform repetitive separation.

16. The device according to claim 1, configured to be introduced into a patient's intestine through the patient's stomach.

17. A gastrointestinal luminal device (10) for deploying markers (42, 44, 46) in a patient's gastrointestinal tract, the device being optionally a device as defined in claim 1, the device being insertable retractably into the gastrointestinal tract and capable of following a tortuous path in the small intestine. A flexible tube (12) that can be introduced into a patient's gastrointestinal tract, wherein the flexible tube is at least partially in a retracted state, the flexible tube has a fixed end (12d) and a movable lumen (14), and the flexible tube is expandable by expanding an expandable region (16) of the flexible tube around the movable lumen, so that it can be extended within the tube without substantial movement of the fixed end, and the expansion turns the most distal retracted material (12c) outwardly, whereby the turned-back material extends the deployed length of the flexible tube distally along the path of the gastrointestinal tract, and the retracted material of the movable lumen (12b) is drawn distally within the deployed tube to provide the distal extension, a flexible tube (12); A plurality of marker elements (42, 44, 46) detectable by fluoroscopic imaging; A gastrointestinal tract lumen device (10) comprising the same. **Claim 18** The device according to claim 17, wherein at least one of the marker elements is deployable from a folded state to an expanded state. **Claim 19** The device according to claim 17, wherein at least one of the marker elements is carried by the flexible tube. **Claim 20** The device according to claim 17, further comprising a guide wire insertable through the movable lumen of the flexible tube, wherein at least one of the marker elements is carried by the guide wire. **Claim 21** The device according to claim 17, configured to be introduced into the patient's intestine through the patient's stomach. **Claim 22** A method of introducing a device into a patient's gastrointestinal tract, wherein the device is optionally according to any of claims 1 to 20, the device comprises a flexible tube introducible into the patient's gastrointestinal tract, the flexible tube is at least partially in a retracted state, the flexible tube has a fixed end and a movable lumen, and the method comprises: Expanding an expandable region of the flexible tube around the movable lumen, wherein the expansion turns the most distal retracted material outwardly, whereby the turned-back material extends the deployed length of the flexible tube distally along the path of the gastrointestinal tract, and the retracted material of the movable lumen is drawn distally within the deployed tube to provide the distal extension, whereby the tube is extendable within the tube without substantial movement of the fixed end; A method comprising the above. **Claim 23** The method according to claim 22, further comprising the step of deploying at least one marker element for indicating a predetermined length or position.

24. The method according to claim 23, wherein the step of deploying the marker element includes expanding the marker element.

25. The method according to claim 23, further comprising the step of deploying at least a second marker element.

26. The method according to claim 22, further comprising the step of introducing the flexible tube through the patient's mouth and stomach into the gastrointestinal tract, optionally partially into the intestine.

27. A method for identifying a target position within a patient's gastrointestinal tract, the method comprising: providing an apparatus comprising a flexible tube introducible into the patient's gastrointestinal tract, the flexible tube being at least partially in a retracted state and having a fixed end and a movable lumen; expanding an expandable region of the flexible tube around the movable lumen, the expansion causing the most distal retracted material to be turned inside out, whereby the turned inside out material extends the deployed length of the flexible tube distally along the path of the gastrointestinal tract and the retracted material of the movable lumen is drawn distally within the deployed tube to provide a distal extension; deploying at least one marker element for identifying the target site and.

28. A method for measuring a distance within a patient's gastrointestinal tract, the method comprising: providing an apparatus comprising a flexible tube introducible into the patient's gastrointestinal tract, the flexible tube being at least partially in a retracted state and having a fixed end and a movable lumen; expanding an expandable region of the flexible tube around the movable lumen, the expansion causing the most distal retracted material to be turned inside out, whereby the turned inside out material extends the deployed length of the flexible tube distally along the path of the gastrointestinal tract and the retracted material of the movable lumen is drawn distally within the deployed tube to provide a distal extension; deploying at least a first marker element and a second marker element having a predetermined interval and.

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