referring to fig1 there is shown a double ended needle enclosed within an anterior guard 10 and a posterior guard 12 . the junction therebetween is sealed with a band of conventional sealing tape 14 . as the two guards and sealing tape are essentially impermable , the double ended needle closed therein can be maintained sterile for an indeterminate period . the anterior guard includes a cap 16 having a tab 18 formed as part of the cap through a frangible boss 20 . a plug 22 extends from the tab for sealingly engaging the aperture formed in cap 16 upon disengagement of boss 20 therefrom . anterior guard 10 and posterior guard 12 are predominantly oval or oblong in cross section to minimize rolling upon a surface and to prevent rotation of the guards relative to the longitudinal axis of the enclosed needle . anterior guard 10 may include opposed flats 24 to assist in gripping the guard along with segmented grooves 26 to assist in a user gripping and manipulating the guard . similarly , posterior guard 12 may include opposed flats 28 and grooves ( not shown ). to expose the double ended needle for use , sealing tape 14 is removed and posterior guard 12 is translated posteriorly to expose hub 30 and the posterior needle enclosed within sheath 32 . the posterior end of the hub includes a threaded section 34 for engagement with the threads attendant a blood collection tube holder ( not shown ). thereafter , anterior guard 10 is griped to insert the posterior needle and sheath 22 within the blood collection tube holder and to attach hub 36 to the holder by means of threaded section 34 . after attachment of the hub ( the attachment is well known and is not shown for sake of clarity of illustration ), tab 18 is gripped and twisted , or otherwise manipulated with respect to anterior guard 10 to sever boss 20 from the end of cap 16 , as illustrated in fig3 . upon severance , an aperture 38 is formed in the cap . this aperture permits exteriorization of anterior needle 40 from within anterior guard 10 upon posterior axial translation of the anterior guard . fig4 illustrates certain details attendant cap 16 . the anterior end of anterior guard 10 may include a ramp 42 defining , in part , an annular depression 44 . cap 16 includes a radially inwardly oriented ramp 46 formed as part of skirt 48 to cooperatively engage with ramp 42 and guide cap 16 onto the anterior end of anterior guard 10 . a lip 50 of ramp 46 drops into and is retained within depression 44 upon attachment of the cap to secure the cap to the anterior guard . the junction between cap 16 and anterior guard 10 may be a force fit to establish a seal therebetween ; in addition , ultrasonic techniques or an adhesive may be employed to develope the point of attachment and seal . by employing a cap 16 to seal the anterior end of anterior guard 10 , initial assembly of the anterior guard upon the double ended needle may be from the posterior end of the needle . such assembly is preferred for reasons recited below . it may be noted that fig4 also illustrates sealing of aperture 38 after use of the double ended needle . after tab 18 has been severed , it is retained until use of the double ended needle has been completed . thereafter , plug 22 of the tab is inserted within aperture 38 . by suitable dimensioning , a force fit can be established to prevent leakage or seepage of any fluid or body substance associated with anterior needle 40 . referring jointly to fig5 to 9 , certain details attendant the structural and operational relationships between anterior guard 10 , posterior guard 12 and double ended needle 36 will be described . boss 20 , in combination with cap 16 define a cavity 56 which produces a frangible skirt 58 of the boss . this skirt is ruptured upon application of a force to tab 18 relative to anterior guard 10 ; moreover , cavity 56 , to the extent it is associated with cap 16 , will define aperture 38 in order to ensure that such aperture is functionally dimensioned to cooperate with plug 22 and effect a seal therebetween . hub 36 is generally oval in cross section in conformance with the cross section of anterior guard 10 and posterior guard 12 . tab 18 may have formed therein opposed depressions 52 , 54 to reduce the mass thereof for manufacturing purposes and to provide a more sure grip of the tab by a user . hub 36 includes an anterior oval shaped flange 60 . this flange serves a number of important functions . the interior dimension of anterior guard 10 tapers posteriorly ; this requires the initial assembly of the anterior guard to be from the posterior end of the hub . as the anterior guard is moved from the retracted to the extended position ( moved anteriorly ), the fit between flange 60 and interior surface 61 of the anterior guard becomes more and more tight . the tight fit between the flange and the anterior guard serves as support for the anterior guard to reduce any tendency of the anterior guard to wobble when in the extended position . to permit the flange to conform with the reduced taper of the anterior guard resulting in compression of the flange , a plurality of slots 62 are formed therein , as illustrated in fig9 . hub 36 includes a piston 64 oval in cross section and conforming , generally , with the interior cross section of anterior guard 10 . because of the taper of the anterior guard , extension of the anterior guard will result in a tendency of the anterior guard to compress piston 64 . such compression establishes a tight fit therebetween to prevent seepage of any fluids or blood substances dripping from a otherwise discharged from needle 40 after use of the needle . it also prevents the likelihood of separation between the hub and the anterior guard . accordingly , piston 64 precludes flow of body substances posteriorly toward hub 36 and the body substance becomes isolated within the anterior guard . piston 64 also provides the function of a robust support for the anterior guard . the combination of support provided by flange 60 and piston 64 to the anterior guard helps assure against wobble of the anterior guard when the latter is in the extended position and against disengagement between the anterior guard and the hub . hub 36 includes a plurality of axially oriented ridges 66 , 68 , 70 , 72 , 74 and 76 . these ridges are formed to reduce the mass of the hub and to facilitate certain manufacturing functions . primarily , the ridges provide six axially oriented surface areas for supporting anterior guard 10 upon axial translation of the anterior guard with respect to hub 36 . the posterior end of anterior guard 10 includes a radially inwardly oriented ridge 80 , which ridge , in cooperation with hub 36 , supports the posterior end of the anterior guard . in the first position of anterior guard 10 , the position prior to use , ridge 80 is located adjacent a ramp 82 extending radially from each of axial ridges 66 - 76 . these ramps discourage posterior translation of the anterior guard . however , the height of the ramps , in combination with the flexibility of the posterior end of the anterior guard permits translation of the anterior guard posteriorly therepast upon application of a modest force to the anterior guard . upon such translation , the anterior guard is retracted to expose anterior needle 40 . the posterior end of hub 36 includes a ramp 84 extending radially outwardly from each of ridges 66 - 76 and a lip 86 disposed upon each of the axial ridges and posteriorly displaced from ramps 84 by a space approximately equivalent to the width of annular ridge 80 of the anterior guard . upon retraction of the anterior guard , ridge 80 is forced past ramps 84 into abutting relationship with lips 86 . the effect of ramps 84 is that of discouraging annular ridge 80 from anterior movement therepast ; they will cause anterior guard 10 to be selectively retained adjacent lips 86 in a second position corresponding to retraction of the anterior guard . upon extension of the anterior guard from the second position , annular ridge 80 will accommodate translation past ramps 84 . upon further anterior translation of anterior guard 10 , side 88 of annular ridge 80 will abut sloping surface 90 of piston 64 . simultaneously , annular ridge 80 will become displaced within grooves 92 formed in each of axial ridges 66 - 76 . edge 94 of slots 92 is generally radially oriented to discourage posteriorly oriented movement of annular ridge 80 therepast . as discussed above , anterior guard 10 tapers posteriorly . accordingly , extension of the anterior guard posteriorly will produce an increasingly tighter fit between the anterior guard and each of flange 60 and piston 64 . this tight fit , and the friction resulting therefrom , in combination with the mechanical impediment presented by side 94 of slots 92 against annular ridge 80 will serve the function of locking the anterior guard in the third or extended position . to assist a user in translating the anterior guard , diametrically opposed grooves 26 , with the corresponding ridges formed thereby , provide a sure gripping surface . furthermore , flats 24 , which may be roughened , provide a further gripping surface for a user . as illustrated in fig5 posterior guard 12 may be secured to anterior guard 10 in an overlapping relationship . to assist in retaining the posterior guard secured in place , a shallow groove 100 may be formed in the posterior end of the anterior guard for receiving a similarly shallow radially inwardly oriented mound 102 . referring to fig1 , anterior guard 10 is shown in the second or retracted position with respect to hub 36 . in this position , annular ridge 80 is disposed in slots 96 formed in ridges 66 - 76 . anterior needle 40 has been exteriorized through aperture 38 of cap 16 . although a collection tube holder would normally be threadedly engaged with threaded section 34 , it is not shown for purpuses of clarity and illustration of the relationship between the anterior guard and the hub . in fig1 , anterior guard 10 is shown in the third or extended position with respect to hub 36 . in this position , anterior needle 40 is fully enclosed within the anterior guard . since it is not unusual for a fluid or body substance to be coated upon the needle or drip from the point of the needle , containment of such fluid or body substance must be assured . aperture 38 has been closed by insertion of plug 22 extending from tab 18 . accordingly , seepage of fluid or body substance through the aperture is precluded . in the extended or third position , annular ridge 80 is lockingly disposed in slots 92 attendant hub 36 , as described above . both piston 64 and flange 60 have been slightly compressed due to the posterior tapering of the inner surface of the anterior guard . this compression , with the resulting tight fit between piston 64 and the interior surface of the anterior guard will prevent leakage or seepage of any fluid or any body substance form within the anterior guard therepast . accordingly , any fluid or body substance attendant needle 40 will be isolated within the needle guard . it may also be noted that in the third or extended position of the anterior guard , it is stabilized by three annularly located and axially displaced points of support : flange 60 , piston 64 and slots 92 . such multipoint support will maintain the anterior guard stably located with regard to hub 36 and wobble thereof is essentially precluded and the likelihood of disengagement therebetween is substantially reduced . the use of a hub having a plurality of axially aligned ridges for supporting the anterior guard results in several advantages . first , manufacturing consideration attendant shrinkage , cooling and accuracy of the part formed are enhanced . second , unnecessary weight , without jeopardizing structural stability , is eliminated . third , less material is used which will reduce manufacturing costs . fourth , control of and support for translation of a guard therealong is more readily definable and controllable than that of a hub of solid mass . thus , a hub having a plurality of longitudinal ridges represents an advance in the state of the art . the use of a hub having a plurality of axially aligned ridges for supporting the anterior guard results in several advantages . first , manufacturing considerations attendant shrinkage , cooling and accuracy of the part formed are enhanced . second , unnecessary wait , without jeopardizing structural stability and weight , is eliminated . third , control of and support for translation of a guard therealong is more readily definable and controllable than that of a hub of solid mass . thus , a hub having a plurality of longitudinal ridges represents an advance in the state of the art . referring jointly to fig1 , 13 and 14 , there is shown a variant of the hub and a variant of the means for retaining the anterior guard in the first , second and third positions . certain other features to comport therewith have also been modified . specifically , hub 112 is essentially cylindrical in cross section . it includes an annularly expanded cylindrical section 114 and a truncated cone shaped segment 116 . anterior guard 118 includes a radially inwardly extending ridge 120 at the posterior end of the anterior guard . in the first position of the anterior guard , ridge 120 is disposed in a channel 122 formed intermediate annular ring 124 and annular ring 126 . the second position of anterior guard 118 is defined by an annular ring 128 disposed about hub 112 at the posterior end portion thereof . upon posterior translation of anterior guard 118 , ridge 120 will abut ring 128 and the ring prevents further translatory movement of the anterior guard therepast ; it also defines the second position of the anterior guard , as particularly illustrated in fig1 . the third position of the anterior guard is defined by channel 130 disposed intermediate ring 126 and section 114 . to discourage posterior displacement of the anterior guard posteriorly when it is in the third position , ring 126 may extend radially outwardly more than that of ring 124 to provide a greater impediment against passage of ridge 120 thereover . the interior of the annular guard includes a cone shaped band 132 force fitable with segment 116 upon translation of the anterior guard to the third position . accordingly , a sealed engagement between the inner surface and the anterior guard and segment 116 of hub 122 is established to prevent flow therepast of any fluid or body substance which might flow or drip from anterior needle 134 . as discussed above , a cap 16 and tab 18 is attached to the anterior end of anterior guard 118 to provide an initially sealed and after use sealable anterior end . this sealed anterior end of the anterior guard will preclude flow or seepage of any fluid or body substance that might drip or otherwise be dispensed from needle 134 . grooves 26 may be disposed along opposed sides of the anterior guard to assist in manipulating the guard to obtain translatory movement thereof . the needle illustrated with respect to variant 110 is a double ended needle usable primarily with a blood collection holder ( not shown ). such a holder is threadedly engaged with threaded section 34 to penetrably receive needle 136 disposed within but extentable from sheath 32 . as is well known , sheath 32 collapses axially upon insertion of needle 136 through the stopper of a collection tube placed within the collection tube holder . it is to be noted that with respect to variant 110 , a posterior guard , such as guard 12 shown in fig5 and 6 , is attachable to anterior guard 118 in an overlapping relationship adjacent edge 138 and cylindrical surface 140 ( see fig1 ). collection tube holders , used in conjunction with double ended needles , are generally reused . such reuse sometimes tends to wear the female threads disposed in the hub or boss of the collection tube holder . if the wear is sufficient or if the threaded engagement is not firm , disengagement of the double ended needle from the collection tube holder may occur . such unexpected and unwanted disengagement may cause spillage of the blood , or other fluid being collected . to ensure against such inadvertent disengagement , a variant of the above - described anterior guard 10 may be employed , as illustrated in fig1 . anterior guard 10 includes radially inwardly oriented ridge 80 at the posterior end thereof . the above - described corresponding ramp 84 , lip 86 and slot 96 in hub 30 shown in fig1 are eliminated in this variant . such elimination permits posterior translation of the anterior guard commensurate with engagement of the anterior end of the guard with the anterior end of hub 30 . collection tube holder 141 includes a boss 142 having a threaded passageway 143 disposed therein for threadedly engaging hub 30 of double ended needle 36 . the exterior surface of boss 142 defines an oval in cross section , commensurate with the internal cross section of anterior guard 10 , as illustrated in fig7 . such cross section of the boss permits penetrable engagement of the boss with the anterior guard upon posterior translation of the anterior guard to the position illustrated in fig1 . the boss also includes a groove 144 extending thereabout for receiving ridge 80 of anterior guard 10 . the capture of the ridge within the groove , in combination with a certain resiliency of the anterior guard , will tend to retain the anterior guard in locking engagement with boss 142 . because of the oval cross section of double ended needle 36 in combination with the oval cross section of anterior guard 10 , rotation therebetween about the respective longitudinal axis is mechanically precluded . the oval cross section of boss 142 , in combination with capture of anterior guard 10 therewith , will preclude rotation intermediate the boss and the anterior guard . disengagement of the double ended needle from the collection tube holder requires rotation therebetween to effect threaded disengagement . since such rotation is precluded by the engagement between boss 142 and anterior guard 10 , such threaded disengagement between the double ended needle and the collection tube holder is precluded . in the event double ended needle 36 is circular in cross section and anterior guard 10 is commensurately cross sectioned , boss 142 must be cylindrically shaped . engagement of anterior guard 10 with hub 142 , under such circumstances and as illustrated in fig1 , will not preclude rotation between the double ended needle and the collection tube holder . however , relative rotation therebetween may be impeded by dimensioning the anterior guard in such manner that the anterior end or cap thereof engages the anterior end of hub 30 upon engagement of ridge 80 with groove 144 . with such arrangement , any tendency for inadvertent rotation of the double ended needle with respect to the collection tube holder which might result in anterior translation of the double ended needle would be resisted by the anterior end of the anterior guard . thereby , threaded disengagement between the collection tube holder and the double ended needle would be restrained . an internally mounted proximal guard 146 extendable from hub 30 is illustrated in fig1 . the proximal guard may include a ramp 84 lip 86 and slot 96 , as described above , to receive ridge 80 of anterior guard 10 . proximal guard 146 includes a radially inwardly oriented ridge 147 to be retainingly received within a groove 148 disposed about hub 30 , as particularly illustrated in fig1 . it may be appreciated that by suitable dimensioning of proximal guard 146 in combination with the interior surface of anterior guard 10 , ridge 147 is restrained from disengaging with groove 148 when the anterior guard overlaps the proximal guard . accordingly , upon such overlap , the proximal guard is precluded from axial displacement . upon anterior translation of anterior guard 10 , as particularly illustrated in fig1 , proximal guard 146 can be translated posteriorly along hub 30 to enclose therein posterior needle 136 and a sheath 32 extending thereabout , if used . hub 30 includes a slot 149 extending about the posterior end of the hub for receivingly engaging ridge 147 upon posterior translation of the proximal guard . as particularly illustrated in fig1 , the proximal guard may include a plurality of resilient fingers 151 to permit accommodation of ridge 147 into and out of groove 148 and slot 149 . as particularly illustrated in fig2 , groove 148 may be disposed solely upon the upper and lower parts of hub 30 . it is to be understood that the groove may be segmented and extend across each of the ridges of the hub for engagement with commensurate parts of ridge 147 in the proximal guard . similarly , slots 149 may be disposed solely upon the upper and lower parts of the hub although the slots may be , in segmented form , extended about the hub . as particularly illustrated in fig1 , proximal guard 146 is generally oval in cross section to mate with the hub and the anterior guard . however , the proximal guard may be circular in configuration or of other cross section commensurate with the cross sections of a hub and an anterior guard with which it may be used . a single needle embodiment of the present invention is illustrated in fig2 - 24 . anterior guard 150 and attached tab 152 are functionally and structurally virtually equivalent with anterior guard 10 and tab 18 . similarly , posterior guard 154 is virtually the equivalent of posterior guard 12 . sealing tape 156 may be secured at the junction of the anterior and posterior guards to maintain the enclosed needle sterile . the single ended needle 160 , as partially shown in fig2 , includes a hub 162 which may have opposed flats 164 and the cross section of the hub may be generally oblong , as illustrated , to discourage rolling upon a surface . the posterior end of hub 162 includes a conventional luer lock mechanism 166 for engagement with an internally threaded shroud 168 extending from the anterior end of a barrel 170 of a syringe 172 . as is conventional , a hollow cone 174 extends from barrel 170 for mating sealed engagement with an equivalently configured passageway within the posterior end of hub 160 . after removal of posterior guard 154 , hub 162 on anterior guard 150 may be grasped to mate it with syringe 172 by mating luer lock 166 with threads 176 disposed within shroud 168 , as shown in fig1 . thereafter , tab 152 is separated from anterior guard 150 to develope aperture 178 . upon rearward axial translation of the anterior guard , it will be repositioned to it &# 39 ; s second position , as described in further detail with respect to the configuration shown in either fig5 or fig1 . in the second position , as illustrated in fig2 , anterior needle 180 is exteriorized from cap 182 and ready for use upon operation of syringe 172 . the anterior guard is retained in place , as discussed above with respect to fig1 or 14 . it may be noted that translation of the anterior guard is from a location posterior of the point of needle 180 to avoid possibility of inadvertent needle stick . after use of needle 180 , anterior guard 150 is translated anteriorly , also from a possession posterior of the point of the needle . such translation will result in relocation of the anterior guard in the third position , as illustrated in fig1 . thereafter , plug 184 of tab 150 is inserted within aperture 178 to seal it . for reasons discussed above , relocation of anterior chamber 150 in the third position will provide body substance isolation within the anterior guard . as is evident from the above discourse and inspection of the figures discussed , anterior translation of the guard past the anterior end the hub is precluded due to the interference between the anterior guard and the hub . this interference requires that the guard be initially mounted upon the hub from its posterior end before the cap is attached to the guard . such methodology for assembling either single ended or double ended needles is believed to be an advance in the state of the art . referring to fig2 , there is shown a further variant 190 . it includes a hub 192 , which may be similar to hub 112 shown in fig1 . a posterior guard 194 is usable to cover and shield posterior needle 196 of the double ended needle extendign from hub 192 . an anterior guard 198 shiels anterior needle 200 prior to and after use . the needle includes a stopper 202 from which a frangible cap 203 extends . referring jointly to fig2 to 29 , certain features attendant anterior guard 198 will be described in detail . a pair of ridges 204 and 206 extend annularly about the posterior end of hub 192 to define a channel 208 , which channel locates the second position of anterior guard 198 . a ramp 210 , in combination with an annular ridge 212 defines an annular channel 214 . an annular sidewall 216 , in combination with ridge 212 defines a further channel 218 . anterior guard 198 includes a skirt 220 disposed at the posterior end of the anterior guard . it includes a plurality of longitudinally oriented tangs 222 defined by slits 224 , as particularly shown in fig2 . in fig2 , each tang includes a radially inwardly extending flange 226 having a radially oriented sidewall 228 terminating at a point 230 of the flange . in the first position of anterior guard 198 ( fig2 ), flange 226 rests within channel 214 . after cap 203 is broken off from stopper 202 , the anterior guard may be axially translated posteriorly . as illustrated in fig2 , continuing translation of the anterior guard will locate it in the second position , as defined by flange 226 resting within channel 208 . in this position of the anterior guard , needle 200 has been exteriorized through aperture 232 formed within stopper 202 . after the needle has been used , anterior guard 198 is axially translated anteriorly to the extent that flange 226 has been located past channel 214 and into channel 218 . further anterior movement of the anterior guard is precluded by interference between sidewall 228 of the flange and sidewall 216 of hub 192 ( see fig2 ). posterior translation of the anterior guard is restrained by ridge 212 . to prevent an outflow of any fluid or body substance from or about needle 200 , cap 203 may be lodged within aperture 232 . posterior guard 194 encloses threaded section 234 from which a posterior needle 236 extends . as described above , section 234 is intended for mating with a collection tube holder . a sheath 238 , as described above , is mounted in cooperating relationship with posterior needle 236 . referring jointly to fig3 and 31 there is illustrated a variant of skirt 220 shown in fig2 to 29 . herein , skirt 240 defines a cylindrical section having a continuous radially inwardly and anteriorly oriented flange 242 extending from the posterior end of the skirt . this flange serves the same function as flanges 226 extending from tangs 222 of variant 190 . that is , they cooperate with the corresponding positioning elements of hub 192 to locate anterior guard 244 with respect to the hub in each of the first , second and third positions . referring jointly to fig3 , 33 , 34 and 35 a yet further variant of the mechanism for securing an anterior guard 250 upon a hub 252 will be described . an annular ridge 254 , in combination with an annular flange 256 define a channel 258 . an annular skirt 260 , defining an internal cone shaped annular surface 262 is displace anteriorly of flange 256 . a convoluted annular ridge 264 exends radially inwardly from anterior guard 250 . upon initial assembly of anterior guard 250 , the guard is translated posteriorly of needle 266 to enclose it therein . upon contact of convoluted ridge 264 with skirt 260 , the skirt will be bent radially inwardly and the convoluted ridge will be bent radially outwardly . upon further translation of the anterior guard , the convoluted ridge will extend radially inwardly and become seated within channel 258 , as illustrated in fig3 . this is the above - described first position of the anterior guard . upon further translation of the anterior guard posteriorly , convoluted ridge 264 will be compressed / bent sufficiently to override ridge 254 . at the posterior end of the hub , there will be located a further ridge which serves as an impediment or stop to further posterior translation of the anterior guard . this is the above - described second position of the anterior guard . upon anterior translation of the anterior guard , convoluted ridge 264 will be forced over ridge 254 and ridge 256 until it comes to rest within channel 268 disposed between ridge 256 and skirt 260 , as illustrated in fig3 . the interference between the convoluted ridge and the skirt will preclude further anterior translation of anterior guard 250 . thereafter , an aperture 268 formed in the anterior end of the anterior guard to permit exteriorization of needle 266 may be plugged by one of the above described elements . while the principles of the invention have now been made clear in an illustrative embodiment , there will be immediately obvious to those skilled in the art many modifications of structure , arrangement , proportions , elements , materials , and components , used in the practice of the invention which are particularly adapted for specific environments and operating requirement without departing from those principles .
a non - rotatable axially translatable anterior guard exposes , upon posterior translation along a needle supporting hub , the anterior end of the needle ready for use . upon anterior translation of the anterior guard , it lockingly engages the hub to retain the needle therein . a detachable tab creates an aperture in the anterior guard for exteriorizing the needle and upon attachment seals the aperture to isolate within the anterior guard , in combination with the fit between the hub and the anterior sleeve , any body substances remaining with the needle after use . a removable posterior guard encloses the posterior end of the hub to receivingly retain any body substances remaining therewith after use of the needle . the anterior and posterior guards , in combination with sealing tape , permit sterilizing the needle prior to use and isolating there within any body substances after use .