Abstract:
An apparatus and method for locking a catheter within a patient enables the catheter to be easily and securely locked and prevents the catheter from being inadvertently unlocked. The locking catheter includes an elongated body member including a proximal portion and a distal portion, a first proximal member, an elongated flexible member, and a second proximal member releasably couplable to the first proximal member to allow selective locking and unlocking of the elongated flexible member therebetween. The second proximal member includes a channel. The elongated flexible member extends from the distal portion of the elongated body member, through the first proximal member, and through the channel of the second proximal member. The elongated flexible member is slidable through the channel thereby allowing the distal portion of the elongated body member to be drawn toward the proximal portion of the elongated body member to form a loop in the distal portion of the elongated body member.

Description:
CROSS REFERENCE TO RELATED CASE 
     This claims priority to and the benefit of Provisional U.S. patent application Ser. No. 60/195,931 filed Apr. 10, 2000, the entirety of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The invention relates generally to catheters and more particularly to pigtail locking catheters. 
     BACKGROUND INFORMATION 
     Kidney catheterization and bladder catheterization are medical procedures that permit drainage of the kidney or bladder after surgery or when the urinary system is blocked by an obstruction. Catheters designed for draining the bladder can be inserted percutaneously by first piercing the lower abdominal wall with a large hypodermic needle, fitting a cannula over the needle, and then placing the catheter within the bladder. The kidney can be accessed percutaneously through the middle of the back of the patient. Catheters are also used to drain other viscera such as the abdominal cavity, the stomach, and the biliary system. 
     To ensure drainage and inhibit movement of the catheter from its placement in a kidney or bladder, a catheter with a pigtail loop at its distal end is often used. After the catheter is inserted into the kidney or bladder, the pigtail loop is formed at a distal section of the catheter by pulling on a proximal end of a suture. The suture extends through and out of the catheter. A proximal portion of the suture is then secured to hold it in place and retain the loop shape at the distal section of the catheter. 
     One such lockable pigtail loop catheter was available from Boston Scientific Corporation of Natick, Mass. under the name “Microvasive Special Percutaneous Nephrostomy Catheters.” With the Special Percutaneous Nephrostomy Catheter, the suture was secured by screwing a separate, loose cap onto the proximal end of the catheter, thereby trapping the suture and securing it. Other locking arrangements also are known. 
     SUMMARY OF THE INVENTION 
     The invention relates generally to locking catheters and methods for using such locking catheters. In one aspect, the invention involves a locking catheter. The locking catheter includes an elongated body member which defines a central lumen. The elongated body includes a distal portion and a proximal portion where at least a portion of the elongated body is for placement within a patient. The locking catheter further includes a first proximal member disposed at the proximal portion of the elongated body member and defines a central passageway which extends therethrough and is coaxial with the lumen. The locking catheter further includes an elongated flexible member. The elongated flexible member includes a first end and a second end. The first end is coupled to the distal portion of the elongated body member and extends through both at least a portion of the central lumen of the elongated body member and the central passageway of the first proximal member. The second end is disposed external to the elongated body member. The locking catheter further includes a second proximal member releasably couplable to the first proximal member to allow selective locking and unlocking of the elongated flexible member therebetween. The second proximal member defines a central passageway which extends therethrough and a separate channel which also extends therethrough. The elongated flexible member extends through the separate channel and is slidable therethrough to allow the distal portion of the elongated body member to be drawn toward the proximal portion of the elongated body member to form a loop in the distal portion when the first and second proximal members are decoupled. The central passageway of the second proximal member extends coaxially from the central passageway of the first proximal member and the elongated flexible member is compressed between the first and second proximal members and is non-slidable through the separate channel to secure the loop when the first and second proximal members are coupled together. 
     In one embodiment the locking catheter further comprises a grommet which defines a central passageway extending therethrough. The grommet is disposed between the first proximal member and the second proximal member with the central passageway of the grommet coaxial with the central passageway of the second proximal member. The grommet creates a seal between the first proximal member and the second proximal member when the first proximal member is coupled to the second proximal member. 
     In another embodiment, the grommet also defines a channel extending therethrough and the elongated flexible member extends through the channel of the grommet. 
     In still another embodiment, the first proximal member is a female luer connector and the second proximal member is a male luer connector. 
     In yet another embodiment, the central lumen of the elongated body member, the central passageway of the first proximal body, and the central passageway of the second proximal body are configured to receive a stylet. 
     In other embodiments, the elongated member comprises plastic. 
     In still other embodiments, the elongated member includes a plurality of apertures for allowing fluid to flow into and out of the central lumen of the elongated member. 
     In yet other embodiments, the first proximal member includes a valve which is open when the first proximal member is coupled to the second proximal member, and which is closed when the first proximal member is decoupled from the second proximal member. 
     In another embodiment, the first proximal member includes a ratchet and the second proximal member includes teeth. The ratchet engages the teeth when the second proximal member is coupled to the first proximal member and prevents the second proximal member from inadvertently decoupling from the first proximal member. 
     In another embodiment, the first proximal member includes one of a male and female latch and the second proximal member includes the other of a male and female latch. The male latch includes a prong and the female latch includes a notch. The male latch engages the female latch when the first proximal member is coupled to the second proximal member and prevents the first proximal member from inadvertently decoupling from the second proximal member. 
     In yet another embodiment, the first proximal member includes a first latch which includes a first set of teeth and the second proximal member includes a second latch which includes a second set of teeth. The first set of teeth engages the second set of teeth when the first proximal member is coupled to the second proximal member and prevents the first proximal member from inadvertently decoupling from the second proximal member. 
     In still another embodiment, the second proximal member includes a spool to wind the elongated flexible member therearound when the second proximal member is coupled to the first proximal member. 
     In yet another embodiment, the locking catheter further includes a second elongated body member which defines a central lumen extending therethrough. The elongated body member includes a first port and a second port. The first port is removably couplable to the second proximal member and extends coaxially from the central passageway of the second proximal member. The second port is connectable to a device external to the patient. 
     In other embodiments, the first port includes a valve for sealing the central passageway of the second proximal member when the second port is decoupled from the device external to the patient. In some embodiments, the valve is a stopcock. 
     In another aspect, the invention involves a method of locking a catheter in a patient. The method includes providing a locking catheter. The locking catheter includes an elongated body member which defines a central lumen. The elongated body includes a distal portion and a proximal portion where at least a portion of the elongated body member is for placement within a patient. The locking catheter further includes a first proximal member which is disposed at the proximal portion of the elongated body member and defines a central passageway which extends therethrough and is coaxial with the lumen. The locking catheter further includes an elongated flexible member which includes a first end and a second end. The first end is coupled to the distal portion of the elongated body member. The elongated flexible member extends through both at least a portion of the central lumen of the elongated body member and the central passageway of the first proximal member with the second end disposed external to the elongated body member. The locking catheter further includes a second proximal member releasably couplable to the first proximal member to allow selective locking and unlocking of the elongated flexible member therebetween. The second proximal member defines a central passageway extending therethrough and a separate channel also extending therethrough. The elongated flexible member extends through the separate channel and is slidable therethrough to allow the distal portion of the elongated body member to be drawn toward the proximal portion of the elongated body member. 
     The method further includes inserting at least the distal portion of the elongated body member into the patient and pulling the elongated flexible member through the separate channel of the second proximal member to draw the distal portion of the elongated body member toward the proximal portion of the elongated body member and thereby forming a loop in the distal portion. The method further includes coupling the first and second proximal members together to compress and lock the elongated flexible member and secure the loop. 
     In still another aspect, the invention involves a locking catheter. The locking catheter includes an elongated body member defining a central lumen and comprising a distal portion and a proximal portion, where at least a portion of the elongated body member is for placement within a patient. The locking catheter further includes a first proximal member disposed at the proximal portion of the elongated body member and defines a central passageway extending therethrough and a separate channel extending therethrough. The central passageway of the first proximal member is coaxial with the lumen. The locking catheter further includes an elongated flexible member. The elongated flexible member includes a first end and a second end. The first end is coupled to the distal portion of the elongated body member and the elongated flexible member extends through at least a portion of the central lumen of the elongated body member, the central passageway of the first proximal member, and the separate channel. The elongated flexible member is slidable through the separate channel to allow the distal portion of the elongated body member to be drawn toward the proximal portion of the elongated body member to form a loop in the distal portion, with the second end disposed external to the elongated body member. The locking catheter further comprises a second proximal member releasably couplable to the first proximal member to allow selective locking and unlocking of the elongated flexible member therebetween. The second proximal member defines a central passageway extending therethrough, and the central passageway of the second proximal member extends coaxially from the central passageway of the first proximal member. The elongated flexible member is compressed between the first and second proximal members and is non-slidable through the separate channel and secures the loop when the first and second proximal members are coupled together. 
     The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description, the drawings, and from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. 
     FIG. 1A is an illustrative diagram of a locking-pigtail catheter according to one embodiment of the invention. 
     FIG. 1B is an illustrative perspective pulled-apart view of the male and female luer connectors of the locking-pigtail catheter shown in FIG.  1 A. 
     FIG. 1C is an illustrative diagram of the locking-pigtail catheter disposed within a patient in an unlocked position according to one embodiment of the invention. 
     FIG. 1D is an illustrative diagram of the locking-pigtail catheter disposed within a patient in a locked position according to one embodiment of the invention. 
     FIG. 2 is an illustrative perspective view of a locking-pigtail catheter and a connection tube according to one embodiment of the invention. 
     FIG. 3A is an illustrative perspective view of a possible arrangement of the components of the lock and the elongated flexible member of the locking-pigtail catheter shown in FIG.  1 A. 
     FIG. 3B is an illustrative perspective view of a possible arrangement of the grommet and the elongated flexible member according to another embodiment of the invention. 
     FIG. 3C is an illustrative perspective view of a possible arrangement of the grommet and the elongated flexible member according to yet another embodiment of the invention. 
     FIG. 3D is an illustrative perspective view of a possible arrangement of the grommet and the elongated flexible member according to still another embodiment of the invention. 
     FIG. 3E is an illustrative perspective view of a possible arrangement of the grommet and the elongated flexible member according to yet another embodiment of the invention. 
     FIG. 3F is an illustrative perspective pulled-apart view of the male and female luer connectors of the locking-pigtail catheter according to another embodiment of the invention. 
     FIG. 3G is an illustrative perspective pulled-apart view of the male and female luer connectors of the locking-pigtail catheter according to still another embodiment of the invention. 
     FIG. 3H is an illustrative perspective pulled-apart view of the male and female luer connectors of the locking-pigtail catheter according to yet another embodiment of the invention. 
     FIG. 3I is an illustrative perspective pulled-apart view of the male and female luer connectors of the locking-pigtail catheter according to still another embodiment of the invention. 
     FIG. 4 is an illustrative diagram in partial longitudinal cross-section of a coupled male and female luer connector according to one embodiment of the invention. 
     FIG. 5 is an illustrative diagram in partial longitudinal cross-section of a coupled male and female luer connector with a mechanism to prevent inadvertent decoupling according to one embodiment of the invention. 
     FIG. 6 is an illustrative diagram in partial longitudinal cross-section of a coupled male and female luer connector with a mechanism to prevent inadvertent decoupling according to another embodiment of the invention. 
     FIG. 7A is an illustrative diagram of a coupled male and female luer connector with a mechanism to prevent inadvertent decoupling according to yet another embodiment of the invention. 
     FIG. 7B is an illustrative diagram in partial longitudinal cross-section of the mechanism to prevent inadvertent decoupling shown in FIG.  7 A. 
     FIG. 7C is an illustrative diagram of a coupled male and female luer connector with a mechanism to prevent inadvertent decoupling according to another embodiment of the invention. 
     FIG. 7D is an illustrative diagram in partial longitudinal cross-section of the mechanism to prevent inadvertent decoupling shown in FIG.  7 C. 
     FIG. 7E is an illustrative top view diagram of the female luer connector portion of the mechanism to prevent inadvertent decoupling shown in FIG.  7 C. 
     FIG. 8 is an illustrative diagram in partial longitudinal cross-section of a decoupled male and female luer connector with a mechanism to prevent inadvertent decoupling according to still another embodiment of the invention. 
     FIG. 9 is an illustrative diagram in partial longitudinal cross-section of a male and female luer connector with a mechanism to prevent inadvertent decoupling according to another embodiment of the invention. 
     FIG. 10A is an illustrative diagram of a coupled male and female luer connector with a mechanism to prevent inadvertent decoupling in an unengaged position according to another embodiment of the invention. 
     FIG. 10B is an illustrative diagram of a coupled male and female luer connector with the mechanism to prevent inadvertent decoupling shown in FIG. 10A in an engaged position. 
     FIG. 10C is an illustrative diagram of the mechanism to prevent inadvertent decoupling shown in FIGS. 10A and 10B being disengaged. 
     FIG. 11A is an illustrative diagram of a locking-pigtail catheter including a spool according to one embodiment of the invention. 
     FIG. 11B is an illustrative diagram a suture wound around the spool of the locking-pigtail catheter shown in FIG.  11 A. 
    
    
     DESCRIPTION 
     The present invention is used to drain viscera such as the kidneys, bladder, abdominal cavity, the stomach, and the biliary system. Referring to FIG. 1A, FIG. 1C, and FIG  1 D, in one embodiment, the pigtail-locking catheter  100  includes an elongated body member  102 , a female luer connector  106 , a male luer connector  112 , and an elongated flexible member  104 . The elongated body member  102  includes a plurality of apertures  110  disposed along the length of the elongated body member  102  and in the distal portion  125 , and a central lumen  131  that extends the entire length of the elongated body member  102 . The plurality of apertures  110  provide access to the central lumen  131  to facilitate fluid flow into and/or out of the elongated body member  102 . The female luer connector  106  includes an opening  108  and a rim  308 . The male luer connector  112  includes an inner wall  134  and a cap  122 . 
     The elongated flexible member  104  is coupled to a distal portion  125  of the elongated body member  102 , extends outside of the elongated body member  102  through a distal opening  130 , and reenters the elongated body member  102  through another opening  128  disposed in a middle section of the elongated body member  102 . The elongated flexible member  104  extends inside the elongated body member  102  through the opening  128  and along the central lumen  131  of the elongated body member  102  to the proximal end  126  of the elongated body member  102 . In one embodiment, the elongated flexible member  104  tied to the distal portion  125 . In other embodiments, the elongated flexible member  104  can be glued to the distal portion  125  or formed in the distal portion  125 . 
     In another embodiment, the elongated flexible member  104  is coupled to the female luer connector  106  and extends through the elongated body member  102  to the distal portion  125 . The elongated flexible member  104  extends outside the elongated body member  102  through the distal opening  130  and reenters the elongated body member  102  through another opening  128  disposed in a middle section of the elongated body member  102 . The elongated flexible member  104  extends inside the elongated body member  102  from the opening  128  and along the central lumen  131  of the elongated body member  102  to the proximal end  126  of the elongated body member  102 . In other embodiments, the elongated flexible member  104  can be glued to the female luer connector  106  or formed in the female luer connector  106 . 
     Referring to FIGS. 1C and 1D, the distal portion  125  of the elongated body member  102  straightened with a stiffening stylet  166  disposed within the central lumen  131  of the elongated body member  102  is inserted into a patient&#39;s bladder, for example, over a guidewire  168 . The stiffening stylet  166  and the guidewire  168  are removed from the patient&#39;s body leaving the distal portion  125  of the elongated body member  102  disposed within the patient&#39;s bladder. The male luer connector  112  is decoupled from the female luer connector  106 . The elongated flexible member  104  is pulled through a channel  118  in the male luer connector  112  to draw the distal portion  125  of the elongated body member toward the proximal portion  126  of the elongated body member to form a loop in the elongated body portion  102 . As the elongated flexible member  104  is pulled through the channel  118 , the male luer connector  112  is moved toward the female luer connector  106  until the male luer connector  112  engages the female luer connector  106 . When the male luer connector  112  engages the female luer connector  106 , an inner wall  134  of the male luer connector  112  is inserted into an opening  108  of the female luer connector  106 . The elongated flexible member  104  is compressed between the rim  308  of the opening  108  and the cap  122  of the male luer connector  112  thereby locking the elongated flexible member  104  in place and locking the distal portion  125  of the elongated body member  102  in the looped position. 
     Referring to FIGS. 1A,  1 B, and  2 , the female luer connector  106  is coupled to the proximal portion  126  of the elongated body member  102  and includes a central passageway that extends therethrough which is coaxial with the central lumen  131  of the elongated body member  102 . The elongated flexible member  104  extends through the central passageway of female luer connector  106  and out of a proximal opening  108 . In one embodiment, the elongated flexible member  104  is a suture thread made of nylon or other similar material of comparable strength. In other embodiments, the elongated flexible member  104  can be a thread or a flexible metal wire. 
     The male luer connector  112  includes an inner wall  134  defining a central passageway  120  that extends therethrough, a cap  122  defining a space  132  between the inner wall  134 , and a channel  118  located in a wall of the cap  120 . The elongated flexible member  104  extends into the space  132  of the male luer connector  112  and exits through the channel  118 . The elongated flexible member  104  includes a knot  105  disposed at the proximal end of the elongated flexible member  104  to prevent the elongated flexible member  104  from sliding out of the channel  118  or the male luer connector  112  from being loose or lost. The elongated flexible member  104  slides through the channel  118  and allows the distal portion  125  to be drawn toward the proximal portion  126  to form a loop in the distal portion  125 . As the elongated flexible member  104  is drawn through the channel  118 , the male luer connector  112  is moved toward the female luer connector  106  until the male luer connector  112  engages the female luer connector  106 . When the male luer connector  112  engages the female luer connector  106 , the inner wall  134  is inserted into the opening  108  of the female luer connector  106  with the central passageway  120  being coaxial with the central passageway in female luer connector  106 . The elongated flexible member  104  is compressed between the rim  308  of the opening  108  and the cap  122  thereby locking the elongated flexible member  104  in place and locking the distal portion  125  of the elongated body member  102  in the pigtail position. By compressing the elongated flexible member  104  between the rim  308  of the opening  108  and the inner wall  134 , the elongated flexible member  104  does not interfere with the seal between the male luer connector  112  and the female luer connector  106  when these two parts are coupled together and does not cause wicking along the elongated flexible member  104  and out of the catheter  100 . 
     In one embodiment, the male luer connector  112  and the female luer connector  106  are made of molded bio-compatible plastic. In other embodiments, the male luer connector  112  and the female luer connector  106  are made of metal, such as surgical steel or aluminum. In still other embodiments, the male luer connector  112  and the female luer connector  106  need not be used and instead, other similar interference fit connectors can be used that will provide a seal and compress the elongated flexible member  104 . The luer connector, male or female, is fitted on the elongated body member  102  by force fitting, gluing, or molding. In some embodiments, the elongated body member  102  can be made of plastic, nylon, polyethylene, ethylene-vinyl acetate co-polymer, or similar material. 
     Referring to FIGS. 1B,  2 , and  3 A, in another embodiment, a grommet  116  made of compressible material is placed inside the space  132  of the cap  122  surrounding the inner wall  134 . When the male luer connector  112  engages the female luer connector  106 , the grommet  116  is compressed between the rim  308  of the opening  108  and the cap  122  and creates a seal between the male luer connector  112  and the female luer connector  106 . As shown in FIGS. 1B and 3A, the elongated flexible member  104  may radially extend through a channel  124  in the grommet  116 . When the male luer connector  112  engages the female luer connector  106 , the grommet  116  is compressed and the grommet  116  thereafter compresses the elongated flexible member  104  (as shown in FIG. 4) thereby locking the elongated flexible member  104  in place and locking the distal portion  125  of the elongated body member  102  in the pigtail position. 
     The elongated flexible member  104  may also be compressed and thereby locked by the grommet  116  in a variety of ways. Referring to FIG. 3B, in one embodiment, the elongated flexible member  104  extends through the central passageway  302  of the grommet  116  and is compressed between the interior surface  310  of the grommet  116  and the exterior surface of inner wall  134 . Referring to FIG. 3C, in another embodiment, the elongated flexible member  104  extends between and is compressed by the exterior surface  312  of the grommet  116  and an interior surface  136  of the cap  122 . Referring to FIG. 3D, in still another embodiment, the elongated flexible member  104  extends longitudinally through the wall of the grommet  116 . When the grommet  116  is compressed, the elongated flexible member  104  is compressed. Referring to FIG. 3E, in yet another embodiment, the elongated flexible member  104  is compressed between the distal face  306  of the grommet  116  and the rim  308  of the female luer connector  106 . In one embodiment, the grommet  116  is made of latex. In other embodiments, the grommet  116  can be made of silicone or foam. 
     The benefit of using the grommet  116  between the male luer connector  112  and the female luer connector  106  is that a better seal is created between the male luer connector  112  and the female luer connector  106 , wicking is prevented in the case where the elongated flexible member  104  is inadvertently compressed between the male luer connector  112  and the female luer connector  106 , and the elongated flexible member  104  is held more securely thereby maintaining the loop in the distal portion  125  of the elongated body member  102 . 
     Referring to FIGS. 3F,  3 G, and  3 H, the positions of the female luer connector  106  and the male luer connector  112  may be reversed. In such embodiments, the male luer connector  112  is coupled to the proximal portion  126  of the elongated body member  102 , and the female luer connector  106  is releasably couplable to the male luer connector  112 . The elongated flexible member  104  may also be compressed and thereby locked by the grommet  116  in a variety of ways as shown in FIGS. 3F,  3 G, and  3 H. 
     Referring to FIG. 3I, in another embodiment, the elongated flexible member  104  exits the central passageway  120  of the male luer connector  112  through an opening  320  in the inner wall  134 . The elongated flexible member  104  pass through the channel  124  in the grommet  116  and then passes through a passageway  322  in the female luer connector  106 . 
     Referring again to FIGS. 1A and 2, the male luer connector  112  includes proximally a female luer portion  114  which is used to mate with a male luer connector  204  of a connection tube  202 . The connection tube  202  is used to connect the locking-pigtail catheter  100  with a medical device such as a collecting bag, for example. 
     Referring to FIG. 4, typically, the male luer connector  112  and the female luer connector  106  are threaded and are held together when the threads  402  of the male luer connector  112  engage the threads  404  of the female luer connector  106 . The male luer connector  204  of connection tube  202  and the female luer portion  114  of the male luer connector  112  are also similarly threaded. The male luer connector  204  and the female portion  114  are held together when the threads  406  of the male luer connector  204  engage the threads  408  of the female luer portion  114 . When a patient attempts to disconnect the connection tube  202  from the locking-pigtail catheter  100 , the patient may accidentally disengage the male luer connector  112  from the female luer connector  106  instead of disengaging the male luer connector  204  from the female portion  114  and thereby unlock the loop in the distal portion  125  and increase the risk of dislodging the catheter  100  from the body cavity. To prevent the male luer connector  112  from being inadvertently disengaged from the female luer  106 , various safety features may be incorporated into the male luer connector  112  and the female luer connector  106  and are discussed below. 
     Referring to FIG. 5, in one embodiment the male luer connector  112  includes a cap  504  which includes one or more prongs  506 . The female luer connector  106  includes one or more notches  502 . When the male luer connector  112  and the female luer connector  106  engage each other (by pushing or screwing them together, for example), the prongs  506  engage the notch  502  and prevent further rotational motion of the male luer connector  112  or the female luer connector  106  and the male luer connector  112  from being inadvertently disconnected from the female luer connector  106 . The male luer connector  112  can only be disengaged from the female luer connector  106  when the cap  504  is squeezed radially and simultaneously at two diametrically opposed positions disposed at a ninety-degree angle from the prongs  506  thereby causing the prongs  506  to lift out of the notch  502 . Alternatively, the notch  502  and the prongs  506  may extend circumferentially, and fitting and release may be done through rigorous pushing together and pulling apart. When the notch  502  is circumferential groove, the male luer connector  112  freely rotates in either a clockwise or counterclockwise direction. 
     Referring to FIG. 6, in another embodiment, the cap  602  includes an outside portion  608  and an inside portion  610 . The outside portion  608  includes teeth  604  disposed on the inside proximal face and extending longitudinally. The inside portion  610  includes teeth  606  disposed on the outside proximal face and extending longitudinally but in the opposite direction of teeth  604 . When the male luer connector  112  and the female luer connector  106  engage each other by screwing them together, the teeth  604  engage the teeth  606  and allow the outer portion  608  to turn the inner portion  610  and thereby tighten the coupling of the male luer connector  112  and the female luer connector  106 . The outer portion  608  spins freely in the opposite (loosening) direction which prevents the male luer connector  112  from being inadvertently unscrewed and disconnected from the female luer connector  106 . The male luer connector  112  can only be disengaged from the female luer connector  106  when the cap  602  is pressed toward the female luer connector  106  and turned in the loosening direction at the same time. Pressing the cap  602  toward the female luer connector  106  causes the outer portion  608  to move toward the inner portion  610  which causes the teeth  604  to engage the teeth  606  and allows the outer portion  608  to turn the inner portion  610  in the loosening direction. 
     Referring to FIGS. 7A and 7B, in still another embodiment, the cap  708  includes a spring-loaded slidable ratchet  702  with a spring  706  and the slidable ratchet  702  mounted over a slide  710 . The female luer connector  106  includes teeth  704  disposed on a proximal face and extending longitudinally. When the male luer connector  112  and the female luer connector  106  engage each other by screwing them together, the teeth  712  in the spring-loaded ratchet  702  engage the teeth  704  and prevent the male luer connector  112  from being inadvertently unscrewed and disconnected from the female luer connector  106 . The male luer connector  112  can only be disengaged from the female luer connector  106  when the spring-loaded ratchet  702  is pressed proximally so that the teeth  704  and  712  disengage while male luer connector  112  is turned. 
     Referring to FIGS. 7C,  7 D, and  7 E, in still another embodiment, the cap  718  includes a spring-loaded slidable ratchet  702  with a spring  706  and the slidable ratchet  702  mounted over a slide  710 . The female luer connector  106  includes holes (or notches)  716  disposed on a proximal face. When the male luer connector  112  and the female luer connector  106  engage each other by screwing them together, the pin  714  in the spring-loaded ratchet  702  engages one of the holes  716  and prevents the male luer connector  112  from being inadvertently unscrewed and disconnected from the female luer connector  106 . The male luer connector  112  can only be disengaged from the female luer connector  106  when the spring-loaded ratchet  702  is pressed proximally so that the pin  714  disengages from one of the holes  716  while male luer connector  112  is turned. 
     Referring to FIG. 8, in yet another embodiment, the cap  808  includes teeth  804 , and the female luer connector  106  includes a flexible but resilient ratchet  802  which includes a tongue  810 , a landing  812 , and a pivot  814 . When the male luer connector  112  and the female luer connector  106  engage each other by screwing them together, the tongue  810  engages the teeth  804  and prevents the male luer connector  112  from being inadvertently unscrewed and disconnected from the female luer connector  106 . The male luer connector  112  can only be disengaged from the female luer connector  106  when the landing  812  is pressed down radially thereby causing the tongue  810  to raise (outwardly via pivot  814 ) and then turning the male luer connector  112 . 
     Referring to FIG. 9, in yet another embodiment, the female luer connector  106  includes right-hand threads  906  and the female portion  114  of the male luer connector  112  includes left-hand threads  904 . The male luer connector  112  and the female luer connector  106  engage each other by screwing together in one direction, and the male luer connector  204  on the connection tube  202  and the female portion  114  engage each other by screwing together in the opposite direction. When the connection tube  202  is disconnected from the female portion  114  of the male luer connector  112 , the male luer connector  204  is turned in a direction that tightens the connection between the male luer connector  112  and the female luer connector  106 , thus preventing the male luer connector  112  from being inadvertently unscrewed and disconnected from the female luer connector  106  and releasing the elongated flexible member  104 . 
     In another embodiment, the female luer connector  106  includes a rotatable connector  910  coupled to the proximal portion  126  of the elongated body member  102 . The rotatable connector  910  includes a first rotating portion  912 , a second rotating portion  914  coaxial with the first rotating portion  912 , and rotation point  916  coaxial with rotating portions  912  and  914 . Rotating portion  912  and  914  are independently rotatable in both the clockwise and counterclockwise directions. The male luer connector  112  and the female luer connector  106  are coupled together by screwing the male luer connector  112  to the female luer connector  106  while holding the rotating portion  912 . After the male luer connector  112  and the female luer connector  106  are coupled together, the male luer connector  112  and the female luer connector  106  will rotate freely about the rotating point  916 , The male luer connector  112  can only be disengaged from the female luer connector  106  by holding the rotating portion  912  while unscrewing the male luer connector  112 . Inadvertently holding any other portion besides rotating portion  912  will prevent decoupling of the male luer connector  112  and the female luer connector  106 . 
     Referring to FIGS. 10A,  10 B, and  10 C, in another embodiment, The cap  1010  includes teeth  1002  extending longitudinally from a distal face, and the female luer connector  106  includes a compressible member  1004  which includes teeth  1006 . When the male luer connector  112  and the female luer connector  106  engage each other by screwing them together, the teeth  1002  engage the teeth  1006  and prevent the male luer connector  112  from being inadvertently unscrewed and disconnected from the female luer connector  106 . The male luer connector  112  can only be disengaged from the female luer connector  106  when the compressible member  1004  is compressed in a direction indicated by arrow  1008 . Compressing the compressible member  1004  causes the teeth  1002  to disengage the teeth  1006  and allows the male luer connector  112  and the female luer connector  106  to be unscrewing. 
     In other embodiments, other safety locking mechanisms can be used to prevent the male luer connector  112  from being inadvertently unscrewed and disconnected from the female luer connector  106  and releasing the elongated flexible member  104 . Additionally, all the components of the safety locking mechanisms previously described above that are part of the male luer connector  112  can be instead part of the female luer connector  106 . Likewise, all the components of the safety locking mechanisms that are part of the female luer connector  106  can be instead part of the male luer connector  112 . 
     In another embodiment, a stopcock valve is connected to and located between the connection tube  202  and the female portion  114  of the male luer connector  112 . The stopcock valve is used to prevent leaking from the locking-pigtail catheter  100  when the connection tube  202  is disconnected from the female portion  114  or from a medical device. 
     Referring to FIGS. 11A and 11B, in still another embodiment, the male luer connector  112  includes a spool  1102  for winding any excess elongated flexible member  104  extending out of the channel  118  of the male luer connector  112  when the male luer connector  112  is coupled to the female luer connector  106 . The end  1104  of the elongated flexible member  104  is coupled to spool  1102 . As the spool  1102  is turned, the elongated flexible member  104  is wound around the spool  1102 . Additionally, the spool  1102  can include a ratchet which prevents the spool  1102  from unwinding unless the ratchet is released, by pushing or pulling the spool  1102  longitudinally, for example. In another embodiment, the spool  1102  may be a circumferential groove disposed in the male luer connector  112  with a slit in the side of the groove to secure the end  1104  of the elongated flexible member  104 . 
     In yet another embodiment, the female luer connector  106  includes a valve disposed in the central passageway of the female luer connector  106 . The valve is closed when the male luer connector  112  is decoupled from the female luer connector  106 . When the male luer connector  112  engages the female luer connector  106 , the inner wall  134  is inserted into the opening  108  of the female luer connector  106  thereby opening the valve disposed in the central passageway in female luer connector  106 . 
     Variations, modifications, and other implementations of what is described herein may occur to those of ordinary skill in the art without departing from the spirit and scope of the invention. Accordingly, the invention is not to be defined only by the preceding illustrative description.