fig1 illustrates dual balloon catheter 10 of the present invention positioned within the male urethra 11 . inflatable location balloon 20 located at the bulbous urethra anchors the device 10 in place and secures it against significant movement in the longitudinal directions , particularly in the direction of the bladder . inflatable dilation balloon 18 is located at the prostate urethra 13 near the prostate 15 and extends into the bladder neck 17 . fig1 shows the location of the male urethra relative to the pubic bone 19 and the urogenital diaphragm ( or pelvic floor ) 21 . fig2 shows the device 10 comprising catheter tube 12 having proximal section 14 for location toward the center of the body on proper insertion of the device 10 in the body , and distal section 16 for location away from the center of the body on proper insertion of the device 10 in the body . the catheter tube 12 is formed of a material which is flexible enough to follow the bends in the urethra on insertion of the device 10 . the material should be rigid enough , however , to allow the device 10 to pass over any obstructions within the urethra on insertion of the device 10 . the catheter tube is composed of or covered by a biocompatible material to avoid irritations and complications in the urethra . suitable biocompatible materials which can be made into tubing of suitable flexibility and rigidity are silicone , polyester , polyvinylchloride , and polyurethane . mounted on the proximal section 14 is axial dilation balloon 18 and axial location balloon 20 . dilation balloon 18 is in communication with the interior of catheter tube 12 , as described in more detail with reference to fig3 . dilation balloon 18 may be replaced by multiple balloons , although one dilation balloon is preferred . the location balloon 20 is at a distance from dilation balloon 18 such that location balloon 20 is at the bulbous urethra when the dilation balloon 18 is at the prostate urethra . balloons 18 and 20 are formed of a biocompatible material such as silicone elastomer , polyvinylchloride , polyester , natural or synthetic rubber , or polyurethane . dilation balloon 18 in general is made such that it does not expand beyond a predetermined diameter . such limited expansion of the balloon 18 prevents overdilation and thus prevents damage to the prostate urethra during dilation . in one embodiment , the limited expansion is attained by making the dilation balloon of a non - distensible material such as polyvinylchloride , polyethylene terephthalate , or polyethylene . in the deflated state , such non - distensible balloon is in a folded configuration . such limited expansion , alternatively , may be attained by making the balloon 18 of a limited distensible composite material as defined above . multi - layer limited distensible materials of use in the present invention are described in cook u . s . pat . no . 4 , 637 , 396 with respect to dilation &# 34 ; balloon 12 &# 34 ; having a three layer wall . the inner layer is an elastic impervious polyurethane membrance , the middle layer is a knitted fabric tube , and the outer layer is an elastic impervious polyurethane membrance . other multi - layer limited distensible materials of use in the present invention are the bistable materials described in u . s . pat . no . 4 , 651 , 721 , the disclosure of which is incorporated by reference . the limited distensible material may be part of a three layer composite having an outer layer which is elastic and may be formed of silicone elastomer , a middle layer of a bistable material such as polyester / polyurethane fabric , and an inner layer which is elastic and impervious and may be formed of silicone elastomer . the bistable material may be a fabric made of yarns composed of non - distensible fibers such as polyester fibers and distensible fibers such as polyurethane fibers . the distensible fibers allow for collapse of the balloon to about the outer diameter of the catheter tube 12 , and the non - distensible fibers allow for inflation of the balloon to the predetermined diameter . the predetermined diameter of the dilation balloon 18 is generally about 25 mm to about 40 mm . the dilation balloon 18 has a proximal end 22 and a distal end 24 , and the location balloon 20 has a proximal end 26 and a distal end 28 . the distance between the distal end 24 of the dilation balloon 18 and the proximal end 26 of the location balloon 20 varies with the relative location of the prostate urethra and the bulbous urethra in a patient , and is usually from about 1 cm to about 4 cm , most typically 1 cm . the device 10 has a proximal end 30 and a distal end 32 . the proximal end 22 of the dilation balloon 18 is usually about 1 cm to about 3 cm from the proximal end 30 of the device 10 . optionally , the dilation balloon extends beyond the proximal end 30 . the length of the dilation balloon 18 , that is the distance between the proximal end 22 and the distal end 24 , depends on the size of the prostate urethra of a patient . in general , such length of balloon 18 is about 3 cm to about 6 cm , commonly 4 cm , in accordance with the general size of a male prostate urethra . the dilation balloon 18 may extend beyond the prostate urethra into the bladder neck , so allowing for some flexibility in use of a limited number of lengths of dilation balloons for different lengths of prostate urethras . the length of the location balloon 20 , that is the distance between the proximal end 26 and the distal end 28 , is such that the balloon fits in the bulbous urethra of a patient . the balloon 20 need not occupy the entire space of the bulbous urethra . the functions of the balloon 20 are locating the prostate urethra , and fixating the device 10 against movement within the urethra , particularly against movement in the direction of the bladder . as a general rule , the length of the location balloon 20 is about 1 cm to 6 cm . radiopaque markers 27 and 29 are conveniently used to guide fluoroscopy examination . fig3 shows one embodiment of the dilation balloon 18 , as attached to catheter tube 12 . drainage lumen 34 extends from the opening 31 at proximal end 30 through the catheter tube 12 to bladder drainage hole 36 . the drainage lumen is an optional feature of device 10 . a dilation lumen 38 communicates between a dilation balloon fill port 40 and the dilation balloon 18 through a dilation balloon opening 42 . an inflation lumen 44 communicates between a location balloon fill port 46 and the location balloon 20 through a location balloon opening 48 . each of balloon fill ports 40 and 46 have a catheter valve or syringe fitting 50 and 52 , respectively , to allow for connection of the fill ports with syringes for injection of fluid . before insertion into the urethra , device 10 is in a completely deflated state such that balloons 18 and 20 are collapsed against the exterior of catheter tube 12 . the device 10 is guided into and along the urethra . to facilitate insertion , the device 10 may be guided over a previously inserted guide wire or the drainage lumen 34 may contain a guide wire so increasing the stiffness of the device 10 . the location balloon 20 is properly located at the bulbous urethra . the doctor feels the bulbous urethra by rectal palpation or determines the position of the bulbous urethra by other means such as fluoroscopic guidance . conveniently , the location balloon 20 is inflated to at least some extent when it is in the vicinity of the bulbous urethra as determined by the doctor by rectal palpation or other known means . the location balloon 20 is inflated to its full extent after location at the bulbous urethra . for inflation of the balloon 20 , the inflation lumen 44 leading to the location balloon 20 is connected to an inflating means such as a syringe , and inflation fluid is injected to inflate balloon 20 by fluid pressure . the inflation fluid is preferably a radiopaque fluid for taking of post insertion x - ray , and viewing of the device while in the body . hypaque - 25 and renografin - 60 are examples of suitable radiopaque fluids . sufficient fluid is injected to secure the device 10 in its proper position . once the inflated location balloon 20 is properly located at the bulbous urethra distal from the external sphincter , the doctor knows that the dilation balloon 18 is at its proper location at the prostate urethra since the location balloon 20 of device 10 is at a distance from the dilation balloon 18 such that when location balloon 20 is at the bulbous urethra then the dilation balloon 18 is at the prostate urethra . in this manner , dilation of the external sphincter and the possible harmful effects of such dilation is avoided . the dilation balloon 18 is now connected to a pressure gauge through the dilation lumen 38 , and inflated . the proper inflation pressure for maximum dilation is attained by injecting a volume of fluid equal to the predetermined capacity of balloon 18 , or by determining the maximum pressure on the pressure gauge when exerting pressure on the balloon 18 . as is known in the dilation art in general , fluoroscopy aids in visualizing the extent of the balloon &# 39 ; s expansion and in monitoring the dilation procedure . in the preferred embodiment when the dilation balloon 18 is made of limited distensible material as described above , the balloon 18 expands to its predetermined maximum diameter . after dilation , balloons 18 and 20 are deflated , and the device 10 is removed .
an apparatus for dilation of the prostate urethra comprises a urinary catheter for insertion in the prostate urethra , dilation means mounted on the proximal section of the catheter and in communication with the interior of the catheter , location means mounted axially on the catheter at a distance from the dilation means such that the location means is at the bulbous urethra when the dilation means is at the prostate urethra , and activating means for activating said dilation means and said location means . a method for the treatment of benign prostatic hyperplasia comprises inserting a urinary catheter having dilation means and location means and removing the catheter after dilation .