Blood Serum Collection Tube And Method Of Collection

Abstract

The disclosure relates to an apparatus and a method for removing serum from the uppermost portions of a specimen tube of centrifuged blood, in which the blood serum is disposed in a liquid pool above settled-out cellular solid materials. More particularly, the invention is directed to an easily handleable, readily mailable, collection tube closed at both ends by "one-shot" valve structures comprising self-sealing elastomeric elements pierced by hollow needles. Additionally, at least the lower valve element is definitive of a pistonlike member which is adapted to engage the inner walls of the specimen tube to pump serum therefrom.

Description

BACKGROUND OF THE INVENTION

In the examination of blood samples in pathological laboratories, it is often necessary or desirable to examine blood serum after it has been separated from the suspended cellular material, and for this purpose it is customary to subject the specimen tubes, in which the blood samples are delivered to the laboratory, to centrifuging action to cause the settling of the cells to the bottom of the specimen tube. Since many laboratories process large numbers of blood samples every day, facility of handling specimens, accuracy of labeling of specimens, and the ease of drawing off and retaining serum specimens are important to successful and safe operation.

Quite often, laboratory workers have experienced difficulty in efficiently removing the clear serum from centrifuged blood specimen tube, without disturbing the settled out solid material. Additionally there have been problems in maintaining with accuracy the identity of the source (patient) from which the serum was originally obtained throughout its travels from hospital to laboratory, etc.

Heretofore, the blood serum has been removed from the specimen tube, after the blood has been centrifuged to separate the serum from the clotted cells by drawing the serum off with a conventional syringe; by pouring the serum off through tilting of the specimen tube; by use of pipettes and the like; and or by use of plungerlike apparatus of the type disclosed in U.S. Pat. No. 3,355,098.

SUMMARY OF THE PRESENT INVENTION

The shortcomings of the prior art devices have been overcome by the method and apparatus of the present invention, which provide a new and improved method of collecting serum and a new and improved self-sealing, serum collection tube, and which tube may be directly filled from centrifuged specimen tubes with collected blood serum. The new serum collection tube basically comprises a hollow cylinder whose ends are closed off by novel "one-shot" valves, one of which also functions as a piston member. The valves comprise self-sealing elastomeric end caps pierced by removable hollow needles.

For a more complete understanding of the present invention and its attendant advantages, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the apparatus of the present invention with its upper and lower, "one-shot" valves opened in preparation for collecting a serum sample from a specimen tube;

FIG. 2 is a cross-sectional view of the apparatus of FIG. 1 during serum collection with both valves opened;

FIG. 3 is a cross-sectional view of the apparatus of the invention with the upper end of the collection tube closed off by removal of the upper needle to capture and to retain the serum sample in the collection tube prior to withdrawal of the same from the specimen tube; and

FIG. 4 is a front elevational view of the collection tube with both ends self-sealed and with the blood serum safely trapped therein in accordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, there is shown a conventional centrifuged specimen collection tube 10 having a pool of serum 11 disposed above settled-out, clotted cellular material 12. The specimen tube advantageously may be of the so-called "vacutainer" type sold by Becton-Dickinson Co. for use by medical personnel in withdrawing blood samples from patients for subsequent laboratory analysis. Such specimen tubes typically have inside diameters of approximately five-eighths inch. Their lengths generally will vary depending upon the size of the volumetric samples of blood required. Once drawn, blood samples are centrifuged in accordance with well-known known procedures to separate within the specimen tube 10 the serum 11 and cellular matter 12, as shown in FIG. 1.

The new and improved serum collection apparatus 9 of the present invention, includes an elongated cylindrical collection tube 15 which is open at its upper and lower ends. Integral annular beads or flanges 16, 17 are formed at the upper and lower ends respectively of the collection tube 15, as shown.

In accordance with the principles of the invention, the upper end of the collection tube 15 is closed off by a generally cup-shaped, elastomeric, self-sealing element 18 which is mechanically connected to the collection tube by means of a resilient, split snap ring 19 which engages the outer surface of the element 18, as shown in FIG. 1., to hold the element 18 to the flange 16. Any other suitable mechanical means, such as threads, keys, locks, etc. may be employed in lieu of the snap ring arrangement, as should be understood. The upper sealing element 18 is pierced by a narrow, hollow needle 20, such as a hardened steel syringe needle, which provides communication between the inside of the tube 15 and the atmosphere. Advantageously, the needle 20 mounts a head or grippable portion 21 which is adapted to be grasped by a user to facilitate the subsequent removal of the needle 20 from the sealing element 18 after serum collection. In accordance with the principles of the invention, the sealing element 18 and the needle 20 comprise an upper, selectively actuatable "one-shot" valve.

The upper end of the collection tube, in a manner similar to the lower end, is closed off by a generally cup-shaped, elastomeric, self-sealing element. A resilient split, snap ring 23 or other suitable means mechanically fastens the element 22 to the flanged, lower end of the tube, as shown. In accordance with the principles of the invention, a lower elongated, hollow needle 24, similar in construction to the aforementioned needle 20, extends through the sealing element 22 to provide communication through the lower end of the collection tube. The lower needle 24 mounts a grippable portion 25 which may be readily grasped to remove the needle 24 from the sealing element 22;

As an important aspect of the present invention, the lower cup-shaped element 22 together with the needle 24 also defines a "one-shot" valve, the outer diameter of which is slightly greater than the inner diameter of the tube 10. Thus the sealing element 22 is able to function as a piston element when inserted in telescoping association with the specimen tube. That is to say, the cylindrical outer surfaces of the sealing element 22 are appropriately dimensioned (e.g. slightly greater than five-eighths inch in diameter) so that the element 22 sealingly, slidingly engages the inner walls of the specimen tube when inserted therein, as shown in FIGS. 2 and 3.

In accordance with the invention, blood serum may be removed from the centrifuged specimen tube 10 and securely trapped within the collection tube 15 in the following manner. The lower end of the collection tube 15 is inserted into the specimen tube, as shown in FIG. 2, and plunged downwardly therein, while the upper "one-shot" valve is open to the atmosphere. In accordance with well-known principles of pumps, the serum will be driven by the "pumplike" action of the piston 22 and up through the open needle 24 and into the collection tube 15, without disturbing the clotted matter 12. When sufficient serum has been collected in this manner to cover the needle opening 24', the upper needle 20 is removed from the self-sealing, elastomeric cap 18 by merely gripping the portion 21 and pulling outwardly thereon and then it is discarded. This closes the upper "one-shot" valve and will seal off the upper end of the collection tube 15 to capture the serum collected therein, in accordance with well-known principles of physics, and in spite of the fact that the lower needle 25 is still present in the collection tube.

Thereafter, the collection tube apparatus 9 is withdrawn from the specimen tube 10, as shown in FIG. 3, and the collected serum 11 is permanently trapped in the collection tube 15 by removing the lower needle 24 by grasping and pulling outwardly on the lower gripping portion 25. This closes the lower "one-shot" valve to provide a completely sealed collection tube 15. The lower needle 24 then may be discarded and the filled tube 15 may be readily mailed to pathology laboratories for testing analysis, etc. in a suitable mailing envelope M (shown in phantom in FIG. 1).

In accordance with a more specific aspect of the invention, the sealing elements 18, 22 are advantageously made of rubber and the collection tube 15 is made from glass. The tube 15 has an etched labeling portion 26 integral therewith upon which suitable identifying indicia may be inscribed to ensure accurate handling.

It should be understood that the blood serum collection method and apparatus herein illustrated and described are intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.

Claims

We claim:

1. Apparatus for removing and trapping the upper portions of a pool of liquid contained in a specimen tube having a predetermined inner diameter, comprising:

a. a cylindrical tubular element open at its upper and lower ends and having an outer diameter less than said predetermined inner diameter of the specimen tube,

b. selectively actuatable upper valve means closing off said upper end of said tubular element and being adapted to provide communication between interior upper portions of said tubular element and atmosphere,

c. Lower valve means closing off the lower end of said tubular element and being adapted to communicate between said inner portions of said tubular element and the liquid in said pool,

d. said lower valve means comprising a puncturable, first elastomeric sealing means and a first hollow needle extending therethrough,

e. said elastomeric material possessing sufficient resilience and said first hollow needle being sufficiently narrow whereby on the removal of said first needle from said elastomeric material said lower end of the tubular member will be completely self sealed,

f. said first sealing means defining a cylindrical piston head having an outer diameter slightly greater than said predetermined inner diameter of said specimen tube, whereby said piston head is adapted to make sliding, sealing contact therewith.

2. The apparatus of claim 1, in which:

a. said upper valve means includes a second elastomeric sealing material cover said upper end and a second hollow needle extending therethrough,

b. said second elastomeric material possesses sufficient resilience and said second hollow needle is sufficiently narrow whereby up on the removal of said second needle from said second elastomeric material said upper end of the tubular member will be completely self-sealed.

3. The apparatus of claim 2, in which:

a. the second needle mounts a gripping means by which the second needle may be removed from said second elastomeric material.

4. The apparatus of claim 2, in which:

a. a mechanical means joins said second elastomeric sealing means to said upper end of the tubular member.

5. The apparatus of claim 4, in which:

a. said mechanical means includes a resilient snap ring, and

b. said elastomeric sealing means comprises a generally cup-shaped member,

c. the uppermost end of said tubular member includes an annular bead.

6. The apparatus of claim 1, in which:

a. the first needle mounts a gripping means by which the first needle may be removed from said first elastomeric material.

7. The apparatus of claim 1, in which:

a. a mechanical means joins said first elastomeric sealing means to said lower end of the tubular member.

8. The apparatus of claim 7, in which:

a. said mechanical means includes a resilient snap ring,

b. said elastomeric sealing means comprises a generally cup-shaped member,

c. the uppermost end of said tubular member includes an annular bead.

9. The apparatus of claim 1, in which:

a. said tubular member is transparent.

10. The apparatus of claim 1, in which:

a. said tubular member is glass, and

b. predetermined portions of said glass are etched and thereby adapted to be indicia bearing.

11. A method of removing serum from a specimen tube comprising the steps of:

inserting a tubular plunger closed off at its lower end by a pistonlike element pierced by a hollow needle into the specimen tube to drive serum upwardly therethrough and into said collection tube,

b. maintaining the upper end of said collection tube open to atmosphere while said collection is driven downwardly into said serum,

c. closing off the upper end of said collection tube from atmosphere upon termination of the downward stroke of said collection tube,

d. removing said collection tube from said specimen tube, and

e. closing off the lower end of said collection tube by removing said needle from the lower end thereof.