Specimen Analysis Device

Abstract

A device is provided for separating a biological fluid specimen into liquid and solid constituents for analysis. The illustrated device includes a receptacle for containing a quantity of the specimen in overlying relation to a filter in sheet form supported on a flat surface, and a vacuum source positioned beneath the filter to draw the liquid portion of the specimen through the filter while leaving the solid constituents on the upper surface of the filter for subsequent microscopic analysis.

Description

The present invention is directed to a device for separating a biological fluid specimen such as urine into solid and liquid components for subsequent analysis.

It is desirable to collect and test fresh urine for biochemical content and sediment. Generally, this involves separating the solid and liquid constituents by centrifugation, performing numerous chemical tests in which selected reagents are separately exposed to small portions of the liquid to determine the presence of albumin, sugar, protein, etc. in the sample, and placing the sediment, if any, upon a slide for microscopic examination. A conventional urinalysis, therefore, is quite time-consuming in that it entails numerous steps and involves not only frequent handling of the centrifuged liquid but the application of the sediment to a slide as well.

A principal object of the present invention is to provide an improved device for separating a fluid sample such as a urine specimen into its solid and liquid components.

Another object of the invention is to provide a device for separating the solid and liquid components of a urine sample in such a manner as to provide in the process a slide containing a thin film of sediment suitable for microscopic analysis.

These and other objects of the invention will become apparent with reference to the following detailed description and accompanying drawings, in which:

FIGS. 1 and 2 are prespective views of two separable elements of a device showing various of the features of the present invention;

FIG. 3 is a perspective view of the elements shown in FIGS. 1 and 2 in working relationship with each other and with a third element illustrating how the device may be used;

FIG. 4 is a perspective view showing the form in which the solid and liquid constituents of a sample are supported and contained after the device has been used in accordance with FIG. 3;

FIG. 5 is an enlarged sectional elevational view taken along line 5--5 of FIG. 3;

FIG. 6 is an elevational view of a device constituting an alternate embodiment of the invention;

FIG. 7 is an enlarged sectional elevational view taken along line 7--7 of FIG. 6;

FIG. 8 is an enlarged fragmentary top plan view of the device of FIG. 6; and

FIG. 9 is a perspective view of a portion of the device of FIG. 6 as it might appear being prepared for storage or shipment.

Very generally, there is shown in FIGS. 1-5 of the drawings a device 10 comprising a substantially flat plate 12 defining a recessed grid 14 adjacent its upper surface and having a hollow needle 16 depending from its lower surface. A passageway 18 extends from the grid 14 to and through the needle 16. A filter in the form of a microporous sheet 20 overlies the grid 14, and a retainer 22 having upstanding walls which encircle the grid is positioned on top of the plate 12. The retainer 22 is adapted to contain a quantity of the fluid sample above the filter sheet 20.

In a preferred method of using the device, a sample of a liquid such as urine is placed within the cavity defined by the retainer 22 and the needle 16 is inserted through the puncturable self-sealing closure 24 of a previously evacuated or vacuumized tube 26. This brings the passageway 18 into fluid communication with the interior of the tube 26, causing the liquid portion of the sample to be drawn through the filter sheet 20 into the tube, from which it can be removed as needed for biochemical analysis. Any sediment within the sample, however, is retained on the surface of the filter sheet 20 where it is available without further transfer for microscopic analysis.

More particularly, the plate 12 is preferably formed of a transparent plastic material such as styrene, polypropylene or the like and, in a preferred embodiment, includes a generally rectangular main body portion 28 and a tab 30 which projects from one end edge of the body portion 28 and is of a lesser width. The body portion 28 approximates in size the standard microscope slide, i.e., it is approximately three inches in length by 1 inch in width. The side edges of the tab 30 are provided with a notch 32 at the juncture of the tab and body, and a groove 34 is provided in the lower surface of the plate and interconnects the lower ends of the notches 32. the notches 32 and groove 34 define a line of weakness along which the tab may be fractured or broken away from the body 28 for reasons which will become apparent shortly.

The grid 14 provides support for the filter sheet 20 while at the same time providing for movement of the filtered liquid beneath the sheet to and through the passageway 18. While the grid may be defined in various ways, in the illustrated embodiment, it is formed by providing a plurality of parallel V-shaped small passageways or grooves 36 (FIG. 5) in a generally square area of the upper surface of that end of the body 28 of the plate 12 which is adjacent the tab 30. The grooves are closely spaced and are separated by ridges terminating in peaks 38. The filter sheet 20 rests upon and is supported by the peaks as well as by the rim of the body portion 28 surrounding the grid. Fluid communication between the grooves and throughout the grid 14 is provided by channels 40 (FIGS. 2 and 4) which extend transversely of the grooves and interconnect the ends thereof. Thus, liquid passing through the filter sheet 20 flows into the grooves 36 and channels 40 of the grid 14, from which it is free to flow through the passageway 18 and, ultimately, into the evacuated tube 26, as hereinafter described.

While the above-described grid formation has proven to be quite satisfactory, it would also be possible to insert a pre-formed grid into a shallow cavity provided in the plate 12, or to roughen the surface of the plate, as by sandblasting or etching, to provide for the desired fluid flow beneath the filter sheet 20.

Extending through the tab 30 between its top and bottom surfaces is a hole 42, and secured to the lower surface of the tab is the needle 16. The needle is hollow and its bore 44 defines a portion of the passageway 18, as does the hole 42 which is coaxial with the needle bore. The needle is of a stiff, rigid construction, is reinforced by a hub 46 at its upper end, and terminates in a sharpened point 48 which defines the outlet of the passageway 18. It is thus strong enough and sharp enough to penetrate the sealed closure 24 of the evacuated tube 26. A canal 50 (FIGS. 2, 4 and 5) provided in the upper surface of the plate 12 extends between the upper end of the hole 42 and the grid 14, thus connecting the grooves 36 and channels 40 of the grid with the bore of the needle 16 and, thus, with the interior of the evacuated tube 26 when the needle has penetrated the stopper 24.

Secured to the upper surface of the palte 12 in overlying relation to the grid 14, the rim of the plate which encircles the grid, and tab 30 is the filter sheet 20. The filter sheet rests upon and is supported by the peaks 38 defined by the ridges between the grooves 36 and is secured by a layer 51 of a suitable permanent adhesive to the rim of the plate and to the tab 30 (FIG. 5). Desirably, the filter sheet 20 is a microporous membrane of the millipore type and is comprised of cellulose nitrate, cellulose acetate or a mixture thereof. The pores of the membrane are small enough to be impervious to the passage of the liquid specimen therethrough solely under the influence of gravity and the liquid can thus be supported above the membrane without leakage through the membrane. However, the pores are of a size which will permit the liquid portion but not the sediment of the specimen to pass through the membrane under the additional influence of the pressure differential applied to the specimen when the passageway 18 is placed in communication with the interior of the evacuated tube 26. The sheet is preferably optically transparent so that it is capable of forming a part of a microscopic slide through which light will pass during the examination of the sediment retained by the filter.

Disposed above the filter sheet 20 in overlying relation to the rim of the plate 12 which surrounds the grid 14, and also in overlying relation to the canal 50 and hole 42 of the plate, is the retainer 22. The retainer comprises four interconnected upstanding walls 52 and a flange 54 extending horizontally from the lower edges thereof. The retainer is so proportioned that when properly positioned upon the upper surface of the plate 12, the walls 52 extend upwardly from adjacent the outer edges of the grid 14 and the flange 54 extends laterally outwardly to the adjacent side edges of the plate 12. At its forward end, the flange is contoured to the configuration of the tab 30. As thus positioned, the walls 52, together with the plate 12 and filter sheet 20, define a fluid reservoir 56 above the filter sheet 20 which is adapted to contain a quantity of the liquid specimen, while the flange 54 not only provides an area of contact between the upper surface of the plate (or filter sheet) and the retainer walls 52, but also overlies and seals off the exposed upper end of the hole 42 and the upper portion of the canal 50, thereby sealing these potential openings and preventing air from being drawn therethrough in place of the fluid from the reservoir 56, as is intended. In a preferred embodiment, the reservoir is dimensioned so as to enable it to conveniently contain approximately 5 ml. of the specimen.

To facilitate attachment of the retainer 22 onto the upper surface of the plate 12, it is preferably distributed to the user with a layer or coating 58 of a releasable or contact adhesive applied to the lower surface of the flange 54 and protected by a suitable backing sheet. The user can thus peel the sheet 60 from the flange 54 and place the retainer on the plate in a relatively secure manner. However, the releasable nature of the adhesive permits the retainer to be removed from the plate after the liquid specimen has been drawn out of the reservoir 56 through the filter sheet 20, thereby rendering the plate and filter sheet conveniently usable as a microscope slide.

As an alternative to the adhesive coating 58 referred to above for facilitating the positioning of the retainer 22 on the plate 12, the lower surface of the flange 54 and the upper surface of the rim of the plate surrounding the grid 14 can be provided with interfitting grooves, and suitable means could also be provided for clamping the flange 52 to the plate.

The evacuated tube 26 and closure 24 are of the type frequently used in obtaining blood samples. The tube 26 is in the form of a conventional test tube and is therefore compatible with other laboratory equipment. It has been previously evacuated prior to delivery to the user, and its interior is under a partial vacuum maintained by the closure 24. The closure 24 is formed of a soft rubber which can be readily penetrated by the sharp needle 16, is capable of maintaining a partial vacuum in the tube 26, and seals the opening occupied by the needle when the needle is withdrawn, thereby maintaining the filtered liquid within the tube and preventing bacteria or other contaminants from entering the tube.

While the use of a previously evacuated tube 26 having a self-sealing soft rubber closure 24 is preferred because of the ease with which it can be used and the economy which it provides, it would be possible in the alternative to employ a previously evacuated tube having a closure provided with a valve adapted to be opened upon the insertion of a needle or other tubular member into the closure. In such an instance, the needle would not have to be capable of puncturing the closure but the tube would still collect the liquid portion of the specimen. As still another alternative, the vacuum source could be a chamber continuously evacuated by a pump, with the chamber being adapted to be connected to the needle 16 or other tubular member through a valve, and with suitable means provided for collecting the liquid portion of the specimen.

The use of the device 10 can best be described with reference to the sequence illustrated in FIGS. 1-4 of the drawings. Assuming a specimen of urine has been obtained in the usual manner, the user removes a plate 12 with needle 16 and filter sheet 20 permanently attached, a retainer 22, and an evacuated closed tube 26 from a suitable kit or carton. The backing sheet 60 is removed from the lower surface of the flange 54 of the retainer (FIG. 1) and the retainer is placed in overlying relation to the filter sheet 20, with side edges of the flange contiguous to the side edge of the plate and with the suitably contoured extension of the flange overlying the tab 30 of the plate, including the canal 50 and hole 42. The adhesive layer 58 maintains the retainer on the plate. When so positioned, the walls 52 of the retainer extend upwardly from adjacent the side edges of the grid 14 and define a reservoir 56 into which a quantity such as 5 ml. of the liquid sample is placed. Because of the microporous nature of the filter sheet 20 and the adhesive interconnection between the flange of the retainer and filter sheet, the liquid specimen will remain in the reservoir and neither pass through the filter sheet by gravity nor pass between the flange 54 of the retainer and the filter sheet.

With the capped evacuated tube 26 held in one hand and the assembled plate 12 and filled retainer 22 held in the other, the point 48 of the needle 16 is placed in contact with the center portion of the top surface of the closure 24 and is forced through the closure by the application of a force, as with the thumb, to the upper surface of the extension of the flange 54 which overlies the tab 30. This brings the bore 44 of the needle 16 and, hence, the hole 42 of the tab 30, the canal 50 of the plate, and the grooves and channels 36 and 40 of the grid 14 into communication with the interior of the evacuated tube, creating a pressure differential across the filter sheet 20 and causing the liquid in the reservoir 56 to be drawn through the filter sheet and into the tube. However, the sediment or solid particles, if any, in the specimen will not pass through the filter sheet but will accumulate in a thin layer on the upper surface thereof, as illustrated in FIG. 4.

After the liquid has passed through the filter sheet, which will generally be accomplished in a very short period of time, the needle 16 is withdrawn from the closure 24 and, because of the self-sealing nature of the closure, the liquid is thereby encapsulated in a sealed tube and can be set aside or shipped to an appropriate laboratory for subsequent analysis. The retainer 22, being only releasably bonded to the plate 22, is then removed from the plate and the tab portion 30 of the plate, to which the needle 16 is attached, is fractured from the remainder or body 28 of the plate along the line of weakness defined by the notches 32 and groove 34. This leaves the filter sheet 20, containing the sediment, supported on the upper surface of the plate body 28 (FIG. 4) which is of the size and shape of a conventional microscope slide, permitting and greatly facilitating microscopic examination of the sediment.

There is illustrated in FIGS. 6-9 a device 120 which constitutes an alternate embodiment of the invention. Referring to these figures, there is provided a plate 122 which preferably measures 1 inch by 3 inches, the dimensions of a conventional slide used for microscopic examination. Located generally centrally of the plate 122 is an opening 124, and encircling the opening is a raised ring 125 formed by a flange reversed upon itself to provide an upwardly extending inner, generally central wall 126, a generally flat annular ledge 128, and a depending, generally cylindrical skirt 130. The inner wall 126 and the skirt 130 define therebetween a generally cylindrical socket 131, the surfaces of which taper inwardly slightly toward the ledge 128 to permit the upper cylindrical wall of a base 132, hereinafter described, to be wedged into the socket with a sufficiently tight fit to provide an essentially airtight seal. A taper of 1.degree. has been found to be satisfactory. Preferably, the ring 125 forms an integral part of the plate 122, which is molded from a suitable plastic. The portions of the plate 122 surrounding the ring are strengthened against warping and bending by a rib 134 which is provided on the lower surface of the plate and extends longitudinally thereof adjacent each of its longitudinal side edges.

Secured to the annular ledge 128 of the ring 125, and spanning the cavity defined thereby in vertically spaced relation to the opening 124, is a filter sheet 136. The filter sheet 136 is of the millipore type previously referred to and is cemented or welded to the shoulder 128. In the embodiment of FIGS. 6-9, the filter sheet is not supported by a grid, as in the embodiment previously described. However, a thin plastic grid could be secured to the shoulder 128 beneath the filter sheet 136, if desired.

A retainer 138 is also provided and is adapted to be placed in overlying relation to the ring 125 and to contain a quantity of fresh urine for passage through the filter sheet 136 while leaving behind on the upper surface of the filter sheet any residue or sediment in the urine. The retainer is preferably molded from a plastic such as polyethylene and includes a genrally cylindrical side wall 140 defining a liquid retaining chamber which is tapered so as to be of slightly greater diameter at its lower end than at its upper end.

The lower edge of the side wall 140 of the retainer is offset outwardly and then downwardly to provide a generally annular, horizontally disposed shoulder 142 and a depending, generally cylindrical flange 144. The retainer is so proportioned that it will seat with a watertight seal on the ring 125 of the plate 122, with the flange 144 encircling the skirt 130 of the ring and resting upon the peripheral portion of the filter sheet 136 secured to the ledge 128, and with the inner surface of the wall 140 in generally vertical alignment with the innter surface of the inner wall 126 of the ring. In order to insure such a seal, the outer surface of the skirt 130 and the innter surface of the flange 144 are preferably tapered slightly to permit a wedging action. This can be most easily achieved by flaring the skirt and flange outwardly slightly, thereby providing the desired taper to the generally cylindrical socket 131 as well. A taper of 1.degree. has been found to be satisfactory.

The upper portion of the side wall 140 of the retainer is flared outwardly significantly to provide the upper portion of the retainer with a lip 146 defining a wide mouth which facilitates the introduction of the fresh urine into the retainer.

It is desirable that a fixed quantity of urine be passed through the filter sheet 136 so that the amount of sediment per unit volume can be determined and compared with known standards, so that a fixed quantity of liquid urine will be available for analysis, and so that the amount of urine placed in the retainer will not exceed the capacity of the vacuumized tube or the ability of the vacuum to withdraw the entire amount of urine from the retainer. Accordingly, the lip 146 of the retainer is provided with a spill-over aperture 148 (FIG. 8) which assures that the upper level of the liquid in the retainer will not rise above the lower edge of the lip 146, and thereby assures that the quantity of liquid in the retainer available for passage through the filter sheet 136 will not exceed a predetermined amount. In a preferred embodiment, this amount is 3cc. The liquid which spills over from the lip through the aperture 138 is caught in a trap 150 in the form of a pocket formed adjacent one side of the lip and side wall 140. Thus, it is not necessary to pre-measure a precise quantity of urine for deposition into the retainer but merely to fill the retainer until liquid begins to spill over into the trap 150.

The base 132 is adapted to facilitate the placing of the lower surface of the filter sheet 136 into fluid communication with a vacuum source such as the vacuumized tube previously referred to. The base is also adapted to rest on a flat surface and support the plate 122 and retainer 138 supported on the plate, as when the two are interconnected and the retainer is filled with a urine specimen.

The base includes a generally cylindrical tubular body 152, the upper edge of which is proportioned so as to enable it to be wedged into the socket 131 of the plate 122 to provide a vacuum-tight fit, thereby preventing leakage of air adjacent the periphery of the filter sheet and inefficient use of the vacuum. Disposed internally of the body 152 is a generally funnel-shaped partition 154 which extends downwardly and inwardly from the inner surface of the body wall and terminates in an axial conduit 156 having a vertically extending bore within which is secured a needle 160. The needle may be secured within the bore of the conduit 156 by any suitable bonding agent such as, for example, a potting resin. The needle terminates short of the lower edge of the tubular body 152 so that when the base is supported on a flat surface such as a table top, the point of the needle is disposed above such surface and will not interfere with a stable disposition of the base on the surface.

As in the previously described embodiment, the needle 158 is adapted to penetrate the closure 24 of a suitably evacuated tube 26 when the tube and needle are moved in the direction of each other. To guide the base 132 and tube 26 during such relative movement, the inner walls of the body 152 are provided with inwardly projecting guide wings 162. In the illustrated embodiment, four such wings spaced circumferentially 90.degree. are provided, and the space defined by the wings is slightly greater than the diameter of either the closure 24 or tube 26. The inner edges of the wings converge slightly from their lower ends toward their upper ends, and the lower ends of the wings are cut at an angle to facilitate the introduction of the tube 26 into the interior of the body 152. In order to facilitate gripping of the base for subsequent separation of the base and tube 26, and for subsequent separation of the device into its three components, the lower portion of the outer surface of the tubular body 152 is provided with a plurality of closely spaced, longitudinally extending ribs 164.

In use, the device 120 is assembled by placing the retainer 138 on top of the plate 122, adnd by placing the plate and retainer on top of the base 132, these three components of the device 120 being securely held together by virtue of the wedging action previously described. The device is then supported on a flat surface, this being made possible by the fact that the lower end or point of the needle 160 is recessed upwardly relative to the lower edge of the base.

A freshly passed urine sample is poured into the retainer 138 until the sample begins to overflow into the trap 150. At this point, there will be a predetermined quantity, e.g., 3 cc. of urine, above the filter sheet 136. The device is then carefully raised and with a previously evacuated tube 26 provided with a penetrable closure 24 supported on a flat surface and stabilized with one hand, and with the device 120 grasped firmly in the other, the device is forced downwardly relative to the tube until the needle 160 penetrates the closure, creating a pressure differential across the filter sheet and drawing the fluid portion of the specimen through the sheet while leaving any sediment including cells, crystals, and bacteria supported on the sheet. The liquid portion of the specimn is thus collected in the tube 26 for subsequent chemical and physical testing.

The device is then separated from the tube 26 and disassembled into its three components. The ribs 164 facilitate grasping of the base 132 to aid in such separation and disassembly. The retainer 138 and base 132 may then be discarded. A small amount of stain preservative is then preferably placed on the filter sheet 136 to preserve all elements of the sediment and provide a clear specimen for microscopic examination. The following formula for a stain preservative has been found preferable:

Part I Crystal violet 0.03gm Ammononium oxalate 0.05gm No. 600 Polyox carbowax 10.00gm Part II Safranin 0 0.2gm Ethyl alcohol 10.0gm Glyoxal 2.0gm

The two parts are mixed togther in 100 ml of water.

The stain preserved sediment slide and sealed tube 26 are then shipped to a laboratory for chemical, physical and microscopic examination. To protect the sediment supported on the filter sheet 136 during such shipment, a cap 166 is preferably provided (FIG. 9) which snaps onto the ring 125 of the plate 122 in overlying relation to the upper surface of the filter sheet, with the lower surface of the central portion of the cap spaced slightly from the sediment to avoid contact therewith. Alternatively, provision may be made for fracturing the plate 122 so as to separate the ring from the remainder of the plate, thereby rendering the ring of a suitable size for accommodation within an automatic analysis apparatus. As a still further alternative, provision could be made for rendering the ring 125 fracturable from the remainder of the plate 122 and adapting it for attachment as a cap to the tube 26 and closure 24, thereby permitting shipment of the sediment and liquid portions of the specimen together as a unit to provide added assurance that they will be properly identified during laboratory analysis.

It should be apparent from the above description that devices formed in accordance with the present invention are suitable for use in the analysis of a wide range of liquid specimens and that their use is not confined to the separation of urine into its liquid and solid components. Also, devices formed in accordance with the present invention can be employed in various manners to achieve different desired results.

For example, devices formed in accordance with the present invention could be used to separate bacteria from virus when both are contained in a liquid specimen, or in a specimen previously diluted with liquid, by using a membrane or filter which will pass the virus but not the bacteria. When the invention is employed to separate bacteria from a liquid specimen, the device employed is preferably gas sterilized, as with ethylene oxide, prior to use and a cover, such as that indicated by the numeral 168 in FIG. 6, seals the inlet of the retainer until the device is used. Fluid for bacterial analysis, such as a "clean catch" urine specimen, would be deposited into the retainer immediately after the cap 168 has been removed and is subsequently drawn through the membrane in the manner previously described. The bacteria is retained on the surface of the membrane and a thin layer of nutrient agar is then poured onto the surface of the membrane to a thickness of 1 or 2 millimeters. The nutrient agar supports bacterial growth in an incubator, and colony count or other bacteriologic processes can follow incubation.

A device formed in accordance with the present invention can also be effectively used in connection with the flotation technique for separating solid but very minute particles from a specimen. For example, in separating parasites or ova from a stool specimen, the retainer of a device embodying the present invention is filled with a salt solution of the proper specific gravity and a small amount of the stool specimen is added. The parasites and ova, being of a lighter specific gravity, rise to the top of the liquid. If a cap, such as the cap 168, is applied and the device inverted, the parasites and ova will be immediately beneath the membrane. If a vacuum is then applied through the membrane, liquid will be drawn through the membrane and draw the parasites and ova against the membrane where they will be retained for examination after the device is disassembled.

Also, chemical testing could be conducted on a liquid specimen to determine such characteristics as the pH value of the specimen by placing a suitable indicator (e.g., a piece of chemically impregnated paper) on or adjacent the membrane or within the receiving tube 26.

Various of the features of the invention are set forth in the following claims.

Claims

What is claimed is:

1. A device for separating a biological fluid specimen such as urine into liquid and solid constituents for analysis, said device comprising: plate means including a hollow needle portion defining an elongated passageway having an inlet at one end and an outlet at its opposite end, said needle portion being adapted to connect said elongated passageway to a source of vacuum, said plate means including a generally flat light transmitting plate portion provided with a grid area spaced laterally from said needle portion, a liquid transporting canal interconnecting said grid area and said elongated passageway in said hollow needle portion, a filter in sheet form supported by said grid area, said filter sheet being light transmitting impervious to the passage of the biological fluid therethrough under the influence of gravity alone but being pervious to the passage of the fluid but not solids contained in the fluid under the influence of a pressure differential created when said outlet of said elongated passageway is connected to a vacuum source, wall means defining a reservoir adapted to contain a quantity of the biological fluid specimen in fluid communication with said elongated passageway inlet through said filter sheet, said grid area being adapted to support said filter sheet in generally planar form, and means to facilitate fracturing of said plate means so as to permit said needle portion to be separated from said grid area and the portion of the filter sheet overlying said grid area to render the remaining portion of said plate means usable as a slide for the microscopic examination of solids which have accumulated on the surface of said filter sheet after the outlet of said elongated passageway has been connected in fluid communication with a vacuum source and the liquid portion of the sample has passed through said filter sheet.

2. A device in accordance with claim 1, wherein said wall defining a reservoir is proportioned so as to extend upwardly from said plate in encircling relation to said filter sheet.

3. A device in accordance with claim 1, wherein said generally flat plate portion is further provided with a rim encirclinG said grid area to which said filter sheet is attached in overlying relation to said grid area, and wherein said wall defining a reservoir is provided with a flange adjacent its lower edge adapted to overlie portions of said rim of said plate.

4. A device in accordance with claim 1, wherein means are provided for maintaining the lower portion of said wall defining a reservoir in a predetermined location relative to said filter sheet.

5. A device in accordance with claim 4, wherein said means comprises a releasable adhesive layer on the lower portion of said wall.

6. A device in accordance with claim 1, wherein means are provided for releasably securing said wall defining a reservoir in fluidtight relation to said plate.

7. A device as defined in claim 1 wherein said plate means includes a tab portion of lesser width then said generally flat plate portion, said hollow needle portion being formed integral with said tab portion and depending downwardly from the lower surface thereof, and wherein said means to facilitate fracturing of said plate means comprises a line of weakness defined between said tab portion and said flat plate portion along which said tab portion may be broken away from said flat plate portion.

8. A device for separating a biological fluid specimen such as urine into liquid and solid constituents for analysis, said device comprising: means defining an elongated passageway having an inlet at one end and an outlet at its opposite end, means at said passageway outlet adapted to connect said passageway in fluid communication with a source of vacuum, a filter in sheet form disposed adajcent said passageway, said filter sheet being impervious to the passage of the biological fluid therethrough under the influence of gravity alone but being pervious to the passage of the fluid but not solids contained in the fluid under the influence of a pressure differential created when said outlet of said passageway is connected to said vacuum source, wall means defining a reservoir adapted to contain only a predetermined quantity of the biological fluid specimen in fluid communication with said passageway inlet through said filter sheet, means including an overflow in said wall means defining a trap in communication with said reservoir for receiving a limited amount of fluid introduced into said reservoir in excess of said predetermined quantity, and means for maintaining said filter sheet in generally planar form for subsequent microscopic examination fo the solids which have accumulated on the surface thereof after the outlet of said passageway has been connected in fluid communication with a vacuum source and the liquid portion of the sample has passed through said filter sheet.

9. A device in accordance with claim 8, wherein a plate is provided for supporting said filter sheet in planar relation, said plate being provided with an opening and with an upstanding ring encircling said opening, said filter sheet being secured to the upper edge of said ring in overlying relation to said opening, and wherein said wall defining a reservoir includes a flange adapted to encircle said ring and be wedged into tight fitting, fluid-tight contact with the outer surface thereof.

10. A device in accordance with claim 8, wherein a plate is provided for supporting said filter sheet in planar relation, wherein said plate is provided with an opening defining a portion of said elongated passageway, wherein said filter sheet overlies said opening and is in communication therewith, and wherein said means adapted to connect said passageway in fluid communication with a source of vacuum is adapted to tbe releasably secured to said plate in fluid-tight relation and in fluid communication with said passageway.

11. A device in accordance with claim 10, wherein said plate defines a socket, and wherein said means adapted to connect said passageway in fluid communication with a source of vacuum includes a portion adapted to be received in said socket.

12. A device in accordance with claim 8, wherein said means at said passageway outlet adapted to connect said passageway in fluid communication with a source of vacuum includes an elongated hollow needle terminating at said passageway outlet and adapted to penetrate the stopper of a tube previously evacuated to provide a partial vacuum therein, said means at said passageway outlet further including means extending generally parallel to said needle for engaging the outer peripheral surface of the previously evacuated tube to provide guidance as the tube and needle are moved relative to each other incident to the penetration of the stopper of the tube by said needle.

13. A device in accordance with claim 12, wherein means are provided for supporting said means at said passageway outlet adapted to connect said passageway in fluid communication with a source of vacuum on a flat surface with the needle depending generally vertically downwardly and with the point of the needle adjacent to, but spaced from, the flat surface.