reference is now made to fig1 which illustrates apparatus 10 , constructed and operative in accordance with a preferred embodiment of the present invention , for measurement of a spatial angle change of an orientation axis 12 of urethra 14 of a subject and diagnosis of urinary stress incontinence . apparatus 10 preferably includes a probe 16 which is suitably sized and shaped to be inserted into urethra 14 . probe 16 is preferably substantially rigid and constructed of a medically safe plastic or metal , such as polycarbonate or an austenitic stainless steel . at least one spatial angle sensor 18 is preferably attached to probe 16 , either at a proximal end of probe 16 as shown in fig1 or alternatively at any other position along probe 16 . angle sensor 18 , preferred embodiments of which will be described in greater detail hereinbelow , preferably senses changes in the angle of axis 12 relative to a reference , such as the gravitational vector or a horizontal plane . a fluid pressure sensor 20 is preferably attached to a distal end of probe 16 for sensing fluid pressure of a bladder ( not shown ). alternatively , pressure sensor 20 may be attached to the proximal end of probe 16 or to any other convenient location along the length of the probe , in which case sensor 20 is configured to measure the pressure at the distal end of probe 16 , for example , by providing a lumen in the probe between sensor 20 and the distal end of the probe . pressure sensor 20 may be any conventional type of miniature pressure sensor , such as a diaphragm or piezoelectric type of sensor , for example . a leakage detector 22 is preferably attached to probe 16 , most preferably on an outer surface of the probe adjacent angle sensor 18 . leakage detector 22 may be an electrical conductivity sensor which comprises two metallic rings 24 . if urine leaks from the bladder , a stream of urine flows over rings 24 and reduces the electrical resistance between them . the urine leak can be detected by detecting the change in resistance . angle sensor 18 , pressure sensor 20 and leakage detector 22 may be any sensor known in the art for sensing or measuring angles , pressures and leakage . in a preferred embodiment of the present invention , the angle sensor comprises one or more chip accelerometers , as are known in the art . angle sensor 18 , pressure sensor 20 and leakage detector 22 are preferably in wired communication with a central processing unit ( cpu ) 26 , such as by means of a cable 27 . alternatively , a transmitter 28 may be provided for wireless communication of the sensors 18 and 20 and detector 22 with cpu 26 . transmitter 28 may be mounted on the outside of angle sensor 18 or at the proximal end of probe 16 , for example . preferably a monitor 30 is electrically connected to cpu 26 for displaying information provided by cpu 26 , such as urethral angle , bladder pressure , or leak point pressure , for example . cpu 26 and monitor 30 may be powered either by a battery or external power source ( both not shown ). it will be appreciated that cpu 26 and monitor 30 may include other wired and / or wireless connections for receiving sensor inputs , as well as other function keys and display windows for processing and displaying information . in a preferred embodiment of the present invention , shown in fig1 a rectal pressure sensor 31 is inserted into the subject &# 39 ; s rectum . the rectal pressure is read and displayed simultaneously with the bladder pressure . fig2 a and 2b illustrate a preferred embodiment of angle sensor 18 . angle sensor 18 is preferably contained in a housing 38 , which is shown partially cutaway in fig2 a and 2b . angle sensor 18 comprises one or more hall effect sensors 40 , preferably two such sensors in substantially perpendicular mutual orientation , which are disposed in propinquity with a magnet 42 . magnet 42 preferably is fixedly mounted on a float 44 which floats in a liquid 46 . liquid 46 is preferably sealably contained in an inner container 48 . sensors 40 may be mounted on an outer wall of inner container 48 . as seen in fig2 b , a spatial angle change in axis 12 of urethra 14 , indicated by an arrow 50 , causes a corresponding movement of magnet 42 which is sensed by hall effect sensors 40 , thereby sensing spatial angle change 50 . fig3 a and 3b illustrate another preferred embodiment of an angle sensor 60 . angle sensor 60 preferably includes a resistive element 62 , such as a nichrome wire , partially submerged in a conductive fluid 64 , such as liquid mercury . conductive fluid 64 is preferably sealed in a generally cylindrical vial 66 . the portion of resistive element 62 which is covered by conductive fluid 64 varies with the angle of probe 16 . for example , as seen in fig3 a , a portion 68 of resistive element 62 is submerged in conductive fluid 64 . in fig3 b , a spatial angle change of axis 12 , indicated by an arrow 70 , causes a corresponding increase in the length of portion 68 . the electrical resistance of resistive element 62 varies with the amount of the portion submerged in conductive fluid 64 . the measured resistance is transmitted to cpu 26 ( not shown in fig3 a and 3b ) which converts the resistance into an angular value to determine the change in urethral angle . fig4 a and 4b illustrate yet another preferred embodiment of apparatus 10 , comprising a disposable probe 70 , which is inserted into urethra 14 , as described above , and a reusable sensor unit 72 , to which the probe is coupled , preferably by means of a quick - connect fitting , as is known in the art . probe 70 is preferably manufactured and supplied to users thereof as a sterile unit , along with a sterile sleeve 74 . sensor unit 72 , on the other hand , is not necessarily sterile , and therefore , after probe 70 is coupled to sensor unit 72 , sleeve 74 is unrolled over the sensor unit , to prevent contamination of the probe . probe 70 includes two lumens 78 and 80 , which are preferably concentric , both lumens communicating with respective ports at a distal tip 76 of the probe , which is inserted into the subject &# 39 ; s bladder . lumen 80 communicates with a diaphragm 84 at the proximal end of the probe , which is used in measuring pressure in the bladder , as described below . lumen 78 communicates with a fluid port 82 near the proximal end of probe 70 and is used to pump fluid into the bladder , so that bladder pressure can be controlled while diagnostic measurements are made as a function thereof . these measurements preferably include measuring leak point pressure using leakage sensor 22 , comprising rings 24 , as described above . as shown in fig4 b , diaphragm 84 forms a flexible fluid barrier between lumen 80 in disposable probe 70 and sensing circuitry 86 in reusable sensor unit 72 . the sensing circuitry detects pressure on or displacement of the diaphragm , in order to measure the pressure in the lumen ( and hence in the bladder ) without coming into contact with the fluid . after each use , probe 70 , including diaphragm 84 , is disposed of , while sensor unit 72 is reused . sensing circuitry preferably further includes a solid - state angle sensor , most preferably a chip accelerometer , as described above , and is electrically connected to rings 24 for measurement of bladder leakage . reference is now made to fig5 which is a simplified electronic block diagram of cpu 26 and monitor 30 useful in the apparatus of fig1 . in a preferred embodiment of the present invention , signals from angle sensor 18 , bladder pressure sensor 20 , leak detector 22 and rectal pressure sensor 31 are processed by an analog device 92 and transmitted to a multiplexer 94 . cpu 26 samples data from multiplexer 94 preferably via an analog - to - digital converter 96 . cpu 26 may alternatively sample data received from sensors 18 , 20 and 31 and leakage detector 22 , process the data and display pertinent information on monitor 30 . in preferred embodiments of the present invention , a physician inserts probe 16 ( or equivalently , probe 70 ) into urethra 14 of an incontinent subject , and then reads and analyzes angle , pressure and leakage data from display 30 to determine whether the incontinence is the result of urethral hypermobility or intrinsic sphincter deficiency ( isd ). preferably , rectal pressure sensor 31 is inserted into the subject &# 39 ; s rectum , and data are received therefrom and analyzed together with the data from probe 16 . alternatively or additionally , the cpu may be programmed to analyze the data and assess automatically the likely cause of the incontinence . it is appreciated that various features of the invention which are , for clarity , described in the contexts of separate embodiments may also be provided in combination in a single embodiment . conversely , various features of the invention which are , for brevity , described in the context of a single embodiment may also be provided separately or in any suitable subcombination . it will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove . rather the scope of the present invention is defined only by the claims which follow :
apparatus for diagnosing urinary stress incontinence of a subject , including a substantially rigid , disposable probe insertable into the urethra of the subject , generally along a longitudinal axis of the urethra . a reusable sensor unit , is removably coupled to the probe , for sensing physiological parameters of the subject . the apparatus preferably includes a fluid pressure sensor , contained in the sensor unit , in pressure communication with a distal end of the probe . the probe includes a flexible diaphragm in fluid communication with the distal end . the diaphragm provides the pressure communication between the pressure sensor and the distal end while substantially preventing fluid communication between the distal end and the pressure sensor .