Abstract:
A device ( 10 ) for use within a woman&#39;s urethra for obstructing urine outflow when the pressure in the woman&#39;s abdomen is at or above a threshold pressure level (IAP1). The device ( 10 ) also allows urine outflow when the intra-abdominal pressure is below the threshold pressure level (IAP1). Device ( 10 ) includes a flexible tube ( 15 ) that is configured to be inserted into a urethra, wherein the tube ( 15 ) defines a lumen ( 14 ) that has inlet ( 19 ) and outlet openings. The tube ( 15 ) is configured to receive, conduct and discharge urine. The tube ( 15 ) is further configured such that the lumen ( 14 ) is at least partially obstructed when the pressure on the urethra surrounding the tube ( 15 ) at least meets the threshold pressure (IAP1), and the lumen ( 14 ) is more open when the pressure on the urethra surrounding the tube ( 15 ) is at a level below a second, lower, threshold pressure (IAP2).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation in part of and claims priority from PCT/US15/31446, filed on May 18, 2015, which itself claimed priority from Provisional Application 62/000,090, filed on May 19, 2014. 
     
    
     BACKGROUND 
       [0002]    This disclosure relates to devices for treating incontinence in human females, and in particular to devices that serve to inhibit or prevent the unwanted discharge of urine from the urinary tract. 
         [0003]    Urinary incontinence, or involuntary urine outflow, affects sixteen percent of women in the United States of America. In about seventy five percent of these women, urinary incontinence occurs when the pressure in their abdomen, called the intra-abdominal pressure, or IAP, rises above a threshold pressure, called IAP1; this is called stress urinary incontinence. In about twenty percent of incontinent women, the detrusor muscle of the urinary bladder involuntarily contracts, producing a sudden urge to urinate; this is called urge urinary incontinence. Women with both stress and urge urinary incontinence are said to have mixed urinary incontinence. 
         [0004]    While pharmaceutical treatment is available to relax the detrusor muscle and relieve urge urinary incontinence, there are no pharmaceuticals cleared by the U.S. Food and Drug Administration for treating stress urinary incontinence. Many surgical procedures have been developed to mechanically support the female urethra or to make it more rigid, but these are expensive, have side effects, often do not work and need to be repeated, and are chosen by few incontinent women. Devices to temporarily block urine flow using a urethral catheter whose proximal end expands inside the bladder need to be replaced every time the woman urinates, and are relatively expensive. Palliative measures, such as wearing an absorbent pad and changing it after every urination, are not only expensive but may leave the skin on the inner thighs wet, leading to abrasions and ulcers; while many pads contain deodorants, the residual urine odor is embarrassing for many incontinent women, leading to restricted social contacts and decreasing their quality of life. 
         [0005]    It is thus desirable to provide a device to automatically control urinary discharge during sudden elevation of intra-abdominal pressure, which functions without intervention by the user and which does not impede her normal activities. 
         [0006]    Prior art includes devices inserted through the female urethra into the bladder to seal the bladder neck until the devices are removed, and a device containing a manually operated drainage control valve that is inserted through the female urethra into the bladder. 
       SUMMARY 
       [0007]    This disclosure relates to devices, methods and tools that are involved with controlling human female urinary incontinence without any purposeful intervention by the user, and more particularly to a female incontinence control device which obstructs urine outflow only when the woman coughs, sneezes, laughs, lifts or otherwise causes the pressure in her abdomen to rise above a threshold level, and allows normal urine outflow otherwise when the woman desires to urinate. 
         [0008]    Disclosed herein is a device that automatically inhibits or prevents urinary discharge during elevation of intra-abdominal pressure, which functions without intervention by the user and which does not impede her normal activities. 
         [0009]    Among the features of the disclosure may be noted the provision of a female incontinence device which is automatically activated by increased intra-abdominal pressure, a female incontinence device which is entirely contained within the body of the user, a female incontinence device which can be easily installed and removed, a female incontinence device which can be operationally fixed within the female urethra, a female incontinence device which effectively prevents urinary discharge when such discharge is not desired and permits such discharge when the user desires and the intra-abdominal pressure is less than a threshold pressure, a female incontinence device manufactured of materials which prevent the growth of bacteria on their surfaces, and a method for controlling female stress urinary incontinence and female mixed urinary incontinence. 
         [0010]    Other features of the disclosure will be in part apparent and in part pointed out hereinafter. In accordance with the disclosure, the female incontinence device defines a passageway or lumen having inlet and outlet openings for receiving, conducting and discharging urine. The device is configured such that the lumen is obstructed when the pressure on the urethra surrounding it meets or exceeds a first threshold pressure (sometimes termed herein “IAP1”). The device is also configured such that the lumen defines a fluid path through the device when the pressure on the urethra surrounding it is below IAP1. In non-limiting examples the lumen opens when the IAP is at or below a second, lower threshold pressure (sometimes termed herein “IAP2”). 
         [0011]    In one embodiment, the device is located within the urethra and the device comprises a flexible, elastic tube. In use, the device is located such that at least some of the outer surface of the tube is in contact with the lining of the urethra. Intra-abdominal pressure elevations caused by, for example, coughing or sneezing, are transmitted through the urethra to this tube, causing the lumen within it to collapse and obstruct the flow of urine through the lumen. The tube can be made from an elastic material that returns to its initial inserted shape once intra-abdominal pressure returns to normal. The device thus serves as an elastic flow control valve that is normally open, but is automatically closed by a deformation of the valve due to increased intra-abdominal pressure, which typically results from the patient coughing, laughing, lifting, sneezing, and the like. The device thus inhibits or fully prevents involuntary urine leakage. The device may also include structure (such as a retaining ring) that holds the tube in a selected position within the urethra, ideally such that the proximal part of the device (closest to the urinary bladder) which is in contact with the lining of the urethra is also proximal to the part of the urethra that passes through the musculature of the pelvic floor, so that the musculature helps to retain the device in place in the urethra. 
         [0012]    All examples and features mentioned below can be combined in any technically possible way. 
         [0013]    Featured herein in one non-limiting example is a device for use within a woman&#39;s urethra for obstructing urine outflow when the pressure in the woman&#39;s abdomen rises at or above a threshold pressure level. The device allows urine outflow when the pressure in the woman&#39;s abdomen is lower than the threshold level, for example when the pressure is near the pressure when her abdominal muscles are relaxed. The device includes a flexible tube that is configured to be inserted into the urethra, wherein the tube defines a lumen that has inlet and outlet openings. The tube is configured to receive, conduct and discharge urine. The tube is configured such that the lumen is fully or partially obstructed when the pressure on the urethra surrounding the tube meets or exceeds the threshold pressure. The lumen is more open when the pressure on the urethra surrounding the tube is at a level below the threshold pressure. 
         [0014]    Embodiments may include one of the following features, or any combination thereof. The tube may comprise a material that is configured to return to its original shape after being deformed. The tube may be a hollow cylinder that may be generally in the shape of an elliptic cylinder. The lumen may define a cross-sectional shape that is generally biconvex lens-shaped, or generally elliptical-shaped. The tube may have a cross-sectional shape that is generally biconvex lens-shaped, or generally elliptical-shaped. The tube and the lumen may both have a major axis, where the two major axes are generally parallel or coincident. When the lumen is not constricted, its boundary may be in the shape of an ellipse, a circle, or an axial cross-section of a double-convex lens with sharp edges (hereinafter sometimes referred to as a “cat&#39;s eye” profile); other shapes of the tube and the lumen are possible and are contemplated herein. 
         [0015]    Embodiments may include one of the following features, or any combination thereof. The lumen may be open when the pressure on the urethra surrounding the tube is at about 10 cm of water. The first threshold pressure where the lumen is constricted or closed may be about 100 cm of water. At an intra-abdominal pressure of about 10 cm of water, the lumen may be sufficiently open such that urine is able to flow through the lumen. The tube may have a variable wall thickness around a circumference of the tube. The tube may be configured to collapse at a pressure that is at least as great as the threshold pressure level. The device may comprise a material that is configured to kill bacteria, or inhibit growth of bacteria that come in contact with the device. 
         [0016]    Embodiments may include one of the following features, or any combination thereof. The device may further comprise a retaining ring or another anti-migration feature disposed on the outside of the tube. The retaining ring may be disposed on a proximal end of the tube. The tube and the retaining ring may be unitary. The circumference of the retaining ring may be at least about 18 French. The retaining ring may be separate from the tube, and it may be more rigid than the tube. The retaining ring may comprise an inflatable structure coupled to the outside of the tube, and configured to be filled with a fluid in situ, so as to expand the retaining ring. The retaining ring may include within it a more rigid material, such as medical grade stainless steel. The retaining ring or other antimigration feature may be a separate structure that is coupled to the outside of the tubular section, or it may be formed of the same material and/or integral with the tubular section. The retaining ring/antimigration feature is preferably but not necessarily located on the proximal part of the tubular section. 
         [0017]    Featured herein in another non-limiting example is a method for inhibiting urine outflow in a female, comprising locating a device in the female&#39;s urethra, wherein the device comprises a flexible tube that defines a lumen that has inlet and outlet openings, the tube configured to receive, conduct and discharge urine. The tube is configured such that the lumen is fully or partially obstructed when the pressure on the urethra surrounding the tube meets or exceeds a threshold pressure, and the lumen is more open when the pressure on the urethra surrounding the tube is at a level below the threshold pressure. 
         [0018]    Embodiments may include one of the following features, or any combination thereof. The method may further comprise delivering the device to the urethra through a sheath. The device may be deployed from the sheath into the urethra using an insertion tool that is configured to engage and be released from the device. The insertion tool may (or may not) be further configured to remove the device from the urethra. 
         [0019]    Featured herein in another non-limiting example is a tool kit comprising a tool that is configured to insert into a female urethra, a device that comprises a flexible tube that defines a lumen that has inlet and outlet openings. The tube is configured to receive, conduct and discharge urine. The tube is further configured such that the lumen is fully or partially obstructed when the pressure on the urethra surrounding the tube meets or exceeds a threshold pressure, and the lumen is more open when the pressure on the urethra surrounding the tube is at a level below the threshold pressure. 
         [0020]    Embodiments may include one of the following features, or any combination thereof. The tool may comprise a sheath that carries the device within the sheath. The tool may further comprise a push rod that is configured to move within the sheath, to push the device out of the sheath. The push rod may be further configured to engage the device while the device is located in the urethra such that the device can be removed from the urethra using the push rod. The push rod may comprise a tip that is configured to pass through the device lumen. The tip may further comprise an expansion mechanism that is configured to be selectively expanded such that a largest dimension of the cross-section of the expansion mechanism is greater than the largest dimension of the lumen. The tool kit may further comprise a tool that is configured to remove the device from the urethra. The tool that is configured to remove the device from the urethra may comprise an inflatable structure that is configured to be passed through the device lumen and be inflated to a size that is larger than the lumen, such that the inflatable structure can be used to pull the device out of the urethra. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIGS. 1A, 1B, 1C, 1D and 1E  are top, proximal end, side, perspective and distal end views, respectively, of an embodiment of a device that is configured to inhibit stress urinary incontinence in human females. 
           [0022]      FIG. 2  shows another example of a device that is configured to inhibit stress urinary incontinence in human females. 
           [0023]      FIGS. 3A, 3B and 3C  are side views of an embodiment of a tool that can be used to insert the device of  FIG. 1  into, and remove such device from, the urethra of human females. 
           [0024]      FIG. 4  shows another example of a tool that can be used to insert the device that is configured to inhibit stress urinary incontinence in human females into the urethra of human females. 
           [0025]      FIG. 5  shows an example of a tool that can be used to remove the device that is configured to inhibit stress urinary incontinence in human females from the urethra of human females. 
           [0026]      FIG. 6  shows an example of a construction of a device that is configured to inhibit stress urinary incontinence in human females that facilitates removal of the device from the urethra. 
           [0027]      FIGS. 7A-7D  are side, perspective, proximal end and distal end views, respectively, of another embodiment of a device that is configured to inhibit stress urinary incontinence in human females. 
           [0028]      FIG. 8  shows an example of a device that is configured to inhibit stress urinary incontinence in human females, in place in the urethra. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIGS. 1A-1E  show one embodiment of a device  10  that is configured to inhibit or prevent stress urinary incontinence in a human female. Device  10  may also be used in non-human females, with appropriate modifications of sizes, device design and materials as needed, as would be apparent to one skilled in the technical field given the anatomy and the likely IAP levels in the species. Device  10  comprises a flexible elastic tube  15 , and a retaining ring (or other device retention feature)  16  that has a larger diameter than tube  15 . Tube  15  is configured to be inserted into a urethra. Tube  15  has a lumen with inlet and outlet openings for receiving, conducting and discharging urinary fluid. Tube  15  is configured such that the lumen is fully or partially obstructed when the pressure on the urethra surrounding the tube meets or exceeds a first threshold pressure (IAP1), and such that the lumen is more open when the pressure on the urethra surrounding the tube is at a level below this first threshold pressure. Tube  15  and ring  16  are connected (in one example, they are integral portions of a unitary molded structure) to form a structure. Device  10  can be manufactured as a single piece, or it can be a multi-piece construction. Retaining ring  16  preferably has a circumference that is about as large as or just larger than the circumference of the urethra; this can be but need not be about 18 French (which corresponds to a round tube with a diameter of 6 mm). Retaining ring  16  is constructed and arranged to maintain the location of the device along the long axis of the female urethra. Retaining ring  16  may be separate from tube  15  and made of a material that is more rigid than the tube. 
         [0030]    The cross section of the outside of tube  15  is preferably but not necessarily an ellipse, including the case where the major and minor axes of the ellipse are of equal length, commonly known as a circle. Tube  15  may thus be considered to be a hollow cylinder, preferably but not necessarily an elliptic cylinder. The wall thickness of tube  15  may be consistent around its circumference (as shown in  FIG. 1E ), or it may not be, as further described below. Tube  15  and/or its lumen may have a cat&#39;s eye cross-sectional shape, or a different shape such as elliptical. The tube and its lumen may both have a major axis  31 , and a minor axis  32 . Major axes  31  and/or minor axes  32  may be coincident, or may be parallel, or not. In one non-limiting example, the dimensions of device  10  may be as follows: overall length 19 mm, width of tube 6.7 mm, height of tube 4.3 mm, height of lumen 2.3 mm, width of lumen 4.5 mm, length of retaining ring 2.9 mm, diameter of retaining ring 7.3 mm. 
         [0031]    The distal end  17  (nearest the vulva when the device is inside the female urethra) in this embodiment is toward the upper right of  FIG. 1D . The proximal end  18  (nearest the urinary bladder when the device is inside the female urethra) in this embodiment is toward the lower left of  FIG. 1D . The circumference of the outside of tube  15  can be (but need not be) approximately equal to or just less than the circumference of the inside of the human adult female urethra. Various models with different tube diameters and/or retaining ring diameters may be designed so as to properly fit different women. 
         [0032]    Device  10  is meant to be placed in the mid-urethra of a woman. Device  10  should lie entirely within the urethra. Preferably but not necessarily retaining ring/device retention feature  16  is proximal to the part of the urethra that passes through the musculature of the pelvic floor, so that this musculature helps to retain device  10  in the urethra. When so placed, when her intra-abdominal pressure, abbreviated IAP, is low, the device will be generally tubular in shape, with lumen  14  open. When the woman initiates the micturition reflex, her bladder&#39;s detrusor muscles contract. This causes urine to flow from her bladder through her urethra and through the lumen  14  that is located along the longitudinal axis of device  10 , and exit outside her body. Tube  15  has a central entrance opening  19  to the device (i.e., the opening of lumen  14 ), into which urine flows from the bladder. The fluid pressure of her urine against the inner wall of tube  15  pushes the inner portions of this tube away from the device&#39;s longitudinal axis. This, along with the elasticity of the material from which tube  15  is made, creates a full-length lumen or passageway  14  for urine flow. 
         [0033]    When the woman is not micturating, but raises her IAP by coughing, laughing, sneezing, jogging, lifting or other means, the increased IAP presses her urethra against the outer surfaces of the tube  15 . This collapses the flexible tube, thereby occluding the device lumen  14  where it passes through the distal part of the device, thus blocking urine flow through the device. Once the IAP returns to normal, the flexible, elastic tube returns to its original shape and allows urine flow during micturition. 
         [0034]    In illustrative but non-limiting examples, IAP1 (the pressure which causes the lumen to collapse) is about 100 cm of water. IAP1 can have different levels depending on the person, the body makeup and other factors. It is believed but not required that IAP1 is likely to be in the range of from about 50 to about 100 cm of water. The device and its tube can be configured such that the lumen collapses at a design IAP1. Relevant tube design parameters include but are not limited to: material, wall thickness, wall cross-sectional shape and lumen cross-sectional shape. IAP2 (the lower pressure where the lumen reopens after having been closed) is preferably but not necessarily designed to be a normal IAP. This depends on whether the woman is standing, sitting or lying down, whether she is thin, average or obese, etc. IAP2 is believed to be anywhere from about 10 to about 40 cm of water. This disclosure, however, is specifically not limited by any values of IAP1 or IAP2. 
         [0035]    Device  10  can be constructed of a material that returns to its original shape after being deformed by the increased IAP. The material(s) may be biocompatible materials such as polydimethylsiloxane (PDMS), a silicone rubber, or alternatives like thermoplastic polyurethanes made by Bayer, such as Texin and Desmopan or other elastomers. Tube  15  along some or all of its length needs to have sufficient elasticity that it returns to its original shape after having been deformed. The more rigid parts of the device if present (e.g., the retaining ring) can be machined or molded from a biocompatible plastic such as polyetheretherketone (e.g., Zeniva PEEK from Solvay Advanced Polymers LLC in Alpharetta, Ga., USA) with polysulfone, polyphenylsulfone, ABS, high density polyethylene or polyetherimide as alternative biocompatible plastics. 
         [0036]    Ionic silver in a zeolite carrier from Agion Technologies, a brand of Sciessent LLC in Wakefield, Mass., USA, or equivalent antimicrobial compounds, can be incorporated into these flexible and more rigid materials to give them antimicrobial properties. Patterns may also be constructed on all surfaces of the device which prevent bacteria from adhering to such surfaces and thereby prevent the formation of biofilms, such as those produced by Sharklet Technologies Inc. of Aurora, Colo., USA, or other such patterns and surface finishes. To inhibit or prevent the growth of microbes on the surfaces of the device, an antimicrobial substance can be mixed or compounded into the materials before they are formed into the parts of the device. To inhibit or prevent urine crystals, if any, from adhering to the device all surfaces of the device in contact with urine can be coated with a highly lubricious material, such as a hydrophilic material, polytetrafluoroethylene (PTFE), parylene, polyvinylpyrrolidone-polyurethane interpolymers, or LubriLAST™ (AST Products, Billerica Mass., USA). 
         [0037]    Alternative embodiments of the tube include those with an oval outside diameter, and those with an inside diameter that includes geometric features that facilitate closure during an increase in IAP such as an ellipse or cat&#39;s eye profile. Also, the retaining ring may be made from a rigid or compliant material. 
         [0038]    The retaining ring may have a radial cross-section which is flat on the surface in contact with the tube and round on the surface in contact with the female urethral lining so as to inhibit or prevent damage to and/or erosion of such urethral lining. The retaining ring may be constructed of a single material, preferably a soft material. Alternatively, as shown by alternative device  100 ,  FIG. 2 , retaining ring  106  may be constructed as a flexible outer shell with an inner filling of a liquid such as distilled water, or another biocompatible fluid. If such retaining ring  106  is to be filled with a liquid, a means for filling ring  106  with liquid, in situ, and draining the fluid from the ring (so that the device may be removed from the urethra) may be provided. For example, fluid conduit  108  may be used to add fluid to and withdraw fluid from the inside of ring  106 . Device  100  includes elastic tube  102  with lumen  104 , which may be the same as tube  15  and its lumen  14  of device  10 ,  FIG. 1 . In one example, the device can be molded from a soft material such as a silicone rubber with a 10 durometer on the Shore A scale. The softness of this material means that the retaining ring might become twisted upon insertion, in which case it might not seat properly in the urethra. Additional stiffness and integrity may be provided by reinforcing the retaining ring. One manner in which the retaining ring could be reinforced would be to insert mold a medical grade stainless steel ring,  148 , into the retaining ring. The steel ring could also serve as an anchor point for the loop of suture material,  142 , that can be included to facilitate removal of the device from the urethra, as is explained below. 
         [0039]      FIGS. 3A-3C  shows one embodiment of a tool  70  that can be used to insert the device  10  into, and remove such device from, the urethra of human females. Tool  70  may be part of or may comprise a tool kit for inserting the device into and removing the device from the urethra. The insertion/removal tool  70  consists of a hollow tube or sheath  75  containing a push rod  78  which can move along its long axis within sheath  75 , a graduated insertion depth scale  79 , a ring  72  for advancing and withdrawing push rod  78  within sheath  75 , a tip  76  of the pushrod  78  containing an expansion mechanism  74 , a stop  77 , a finger grip  71 , and a mechanism  73  for operating the expansion mechanism  74 .  FIG. 3A  shows the device  10  inserted into the sheath  75  with the tip  76  passing within and extending from the device  10 . The device  10 , held within tool  70 , is inserted into the human female urethra until a mark on the graduated scale  79  is adjacent to her urethral meatus. The length of the corresponding urethra, measured separately, corresponds to one of the marks on the graduated scale  79 . The marks are located such that once the insertion process is completed the device  10  will be centered along the length of her urethra (or placed in another location in the urethra, as desired or as necessary).  FIG. 3B  shows the device  10  after the sheath  75  is withdrawn while the ring  72  is held still with respect to the woman&#39;s body until the stop  77  is touching the finger grip  71 . Not shown are the human female urethra and its sticky endothelial mucosa holding the device  10  in place while the sheath  75  is withdrawn. Once finger grip  71  touches stop  77 , the insertion/removal device  75  can be completely removed from the urethra. 
         [0040]    In order to remove the device  10  from the female urethra, tool  70  is inserted into the urethra and tip  76  is inserted into the lumen of device  10  until pushrod  78  touches the device&#39;s proximal end and further insertion is resisted.  FIG. 3B  also shows the relative positions of device  10  and tool  70  after tool  70  has been inserted into the urethra and through the lumen of device  10  just prior to removing such device from the urethra. The expansion mechanism  74  is then deployed to lock the device  10  between the pushrod  78  and itself,  74 .  FIG. 3C  shows the mechanism  73  moved towards the ring  72  so as to cause expansion of the expansion mechanism  74 ; this engages the device  10  with the pushrod  78  so that withdrawal of the tool  70  from the urethra will remove device  10  from the urethra. 
         [0041]    More generally and as shown in  FIG. 4 , a tool  110  for inserting into the female urethra a device  112  which is similar to device  10 . Device  112  is configured to inhibit or prevent stress urinary incontinence in a human female. Tool  110  may include a hollow cylinder  114  (preferably but not necessarily of round or elliptical cross-section) into which the device  112  is loaded, an indication such as markings (not shown) on the outside of such cylinder  114  of the distance between such indication and the end of the cylinder that will be closest to the woman&#39;s bladder. There is also a plunger  115  (e.g., a hollow cylinder with an elliptical cross-section that can act as a pushrod) that fits into and can slide within the hollow cylinder  114 , and fits over the stein of device  112  so as to rest against the retaining ring of device  112 . There are also means, such as stop  120 , for holding the indication adjacent to the female urethral meatus while the plunger is pushed via end  116  into the cylinder to expel the device, and a means, such as bilateral finger grips  118 , for use in withdrawing the cylinder from the female urethra. As the hollow cylinder  114  introduces the device into the female urethra, it may be called an introducer sheath. The introducer sheath may be made of or its inside may be coated with a slippery material such as Teflon® to reduce the friction force between the device and the inside of such sheath. 
         [0042]    A different tool  130 ,  FIG. 5 , may be used to remove from the female urethra a device  132  which is similar to device  10 . Device  132  is configured to inhibit or prevent stress urinary incontinence in a human female. Tool  130  may consist of a hollow tube  134  with a balloon  136  at its far end. With the balloon  136  deflated, tube  134  is inserted into the urethra and into the lumen in device  132  until balloon  136  is on the other (facing the patient&#39;s bladder) side of device  132 . The balloon  136  is then inflated with a liquid or gas via inlet  138  so that its outside diameter is greater than the largest dimension of the lumen of device  132 . Tube  134  is then pulled away from the patient&#39;s body, withdrawing the device  132  with it. 
         [0043]    Alternatively or additionally and as shown in  FIG. 6 , a loop  142  of biocompatible material may be fixed (e.g., glued to) to the distal end of device  144  which is similar to device  10 . Device  144  is configured to inhibit or prevent stress urinary incontinence in a human female. Loop  142  facilitates removing device  144  by inserting a tool (not shown) into the female urethra to engage this loop (e.g., using a hook that engages in space  146  behind loop  142 ) and using such tool to pull the device  144  out of the urethra. Loop  142  may be engaged with the steel ring that is in the retaining ring of the device. Loop  142  may be made from a suture material, and may extend to about 10 mm distal to the device so it can be grasped and used to pull the device out of the urethra. 
         [0044]      FIGS. 7A-7D  illustrate another arrangement of the disclosed device. Device  90  is configured to inhibit or prevent stress urinary incontinence in a human female. Device  90  comprises tube  92  that has central lumen  97  with the urine inlet opening in proximal end  95  and outlet opening in distal end  93 . Proximal end  95  can include a domed end portion  94  to facilitate insertion of the device into the female urethra. As can be seen in the end views, lumen  97  is generally shaped as a biconvex lens with sharp edges. Alternatively, the lumen may be more elliptical-shaped. Since tube  92  is round or elliptical, the lumen creates thinner wall portions at locations  97   a  and  97   b  (along the major axis  101  of lumen  97 ) as compared to the thicker wall portions along the minor axis  102  of lumen  97 . This construction causes the tube to preferentially collapse toward major axis  101  (along arrows A and B,  FIG. 7C ) when inward pressure is applied around the circumference of tube  92 . Projection  96  (which in this case is like an integral O-ring) accomplishes a greater diameter near the proximal end that creates a tight fit with the urethra, to help hold or retain the device in place in the urethra. Projection  96  could alternatively be a separate piece that is affixed to the tube. 
         [0045]      FIG. 8  shows device  150  that is configured to inhibit or prevent stress urinary incontinence in a human female in place in urethra  160  that leads from bladder  162  to urethral meatus  164 . Device  150  has retaining feature  154  that indents the urethral wall, and tube  152  that sits close to or against the urethral wall. Urine flows in the direction of arrows  170  and  172 . When IAP increases to IAP1, tube  152  collapses as described above. When IAP subsequently decreases below IAP1 (e.g., to a normal level (IAP2)), tube  152  reopens to allow the flow of urine. 
         [0046]    A number of implementations have been described. Nevertheless, it will be understood that additional modifications may be made without departing from the scope of the inventive concepts described herein, and, accordingly, other embodiments are within the scope of the following claims.