Blood collection tube safety cap

A blood collection assembly is provided for blood collection tubes, and more particularly for evacuated blood collection tubes, whereby the potential exposure of laboratory technicians or hospital personnel to potentially infectious blood specimens is reduced. The device consists of a cap which is configured to be placed over and fitted onto the rubber stopper of an evacuated collection tube. The top surface of the cap includes a centrally located bore section which is surrounded by a downwardly directed retaining ring to prevent accidental exposure of the user to the upper flange portion of the stopper wherein the user is protected from exposure to the contaminated bottom surface of the stopper as the cap and stopper are removed from the collection tube.

Field of the Invention 
This invention relates generally to blood collection tubes and more 
particularly to a three-part blood collection assembly consisting of a 
collection tube, an elastomeric stopper and a protective safety cap. 
Background of the Invention 
The use of evacuated tubes for the collection of blood samples is well 
known. Conventional blood collection tubes consist of a cylindrical 
container or tube having a closed bottom end and an open top end. The 
collection tubes are then evacuated and sealed by a removable 
needle-pierceable stopper or closure. Typically, blood is withdrawn from a 
patient by first puncturing a vein with one end of a double-ended needle 
and then, while firmly holding the needle housing, pushing the 
needle-pierceable stopper of a collection tube against the other end of 
the needle until the stopper is pierced. The partial vacuum within the 
collection tube causes the blood to be drawn or siphoned into the 
collection tube. After the desired volume of blood is drawn into the 
collection tube, the needle is withdrawn from the patient and the blood 
specimen is brought to a laboratory for testing. 
It is fairly common for laboratory technicians or hospital personnel to 
take several samples from a single blood specimen. Because the collection 
tube is originally evacuated, there is often a pressure differential 
between the interior and exterior of the collection tube. Therefore, when 
the technician removes the needle from the diaphragm of the stopper after 
obtaining the sample, there may be a part of the blood specimen which 
contacts and remains on the stopper. For other types of tests, the 
technician may actually remove the stopper from the blood collection tube 
in order to obtain the desired sample. This may expose the technician to 
the bottom of the stopper which has previously been contaminated with the 
blood specimen. Finally, when the technician reinserts the stopper into 
the collection tube, an aerosol of the specimen may be created around the 
perimeter of the stopper due to the slight positive pressure which is 
created within the collection tube as the stopper is reinserted into the 
collection tube. 
The heightened awareness about the potential routes of transmission of 
Acquired Immune Deficiency disease and other infectious diseases has led 
to an increase in research relating to the development of blood collection 
devices which are designed to decrease the likelihood that laboratory 
technicians and hospital personnel will be exposed to the potentially 
infectious blood specimens. One such device is illustrated in U.S. Pat. 
No. 4,465,200, issued to Percarpio on Aug. 14, 1984. The Percarpio device 
consists of a standard blood collection tube and a composite closure 
arrangement consisting of a modified stopper and a protective cap. The 
Percarpio patent relies on the existence of a cavity formed by the annular 
portion of a cap and the inner surface of a well to protect the technician 
from exposure to blood droplets typically present on the top surface of 
the well. An important drawback to the composite closure design disclosed 
by Percarpio is that it requires modification of the upper flange portion 
of the stopper in order to create a tapered annular outer sealing surface 
of the type illustrated in FIG. 1. Additionally, the cap prevents the user 
from being able to visually determine the amount of specimen actually 
deposited on the flexible stopper as the needle is removed from the 
collection tube. As a result, the technician may be unnecessarily exposed 
to the potentially dangerous blood specimen present on the top surface of 
the stopper if the tube is shaken or inverted. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to provide an improved 
blood collection assembly which is relatively economical, simple and 
effective in use, and which substantially overcomes one or more of the 
above-identified problems. 
Another object of the present invention is to provide a blood collection 
assembly which will decrease the likelihood that hospital personnel or 
laboratory technicians will be exposed to the contaminated surfaces on a 
stopper used in blood collection tubes. 
The blood collection assembly of the present invention consists generally 
of a standard blood collection tube, an elastomeric stopper and a 
protective cap. The blood collection tube of the present invention 
includes an open top end and a closed bottom end. The stopper of the 
present invention generally includes a top surface having a top axial 
recess thereon and a bottom surface having a larger concave recess 
thereon. The stopper generally consists of an upper flange portion having 
a circumference larger than the open end of the collection tube and a 
lower plug portion having a circumference slightly larger than the inner 
diameter of the collection tube to create a releasable frictional fit 
between the lower portion of the stopper and the collection tube. 
The cap of the present invention includes a lower annular portion having a 
plurality of inwardly extending retaining lips thereon and a top portion 
having a centrally located small diameter bore section surrounded by a 
downwardly directed retaining ring. When the cap and stopper are assembly 
on the collection tube, the lower annular portion extends downwardly along 
the outer surface of the collection tube beyond the bottom surface of the 
stopper. The retaining ring extends downwardly into the interior of the 
cap to contact the top axial recess located on the top surface of the 
stopper while the inwardly extending retaining lips contact an annular 
ridge formed by the bottom surface of the upper portion of the stopper. 
A second embodiment of the present invention is illustrated in FIGS. 5-7. 
This embodiment is particularly adapted for use with a 16 mm or larger 
blood collection tubes and may be adapted for use with nearly any blood 
collection tube having an inwardly directed annular lip at the open end of 
the blood collection tube. In this embodiment, the stopper includes upper 
and lower groove areas wherein the lower groove area contacts the inwardly 
directed lip on the blood collection tube and the upper groove contacts 
and engages the modified inwardly directed retaining lips on the cap. The 
retaining ring of this embodiment is similar to the retaining ring of the 
first embodiment and extends downwardly into the top axial recess of the 
stopper to allow the user to visually determine whether or not the top 
surface of the stopper has been contaminated. 
An advantage of the present invention is that it is relatively inexpensive 
to manufacture and simple to use. 
A further advantage of the present invention is that the small diameter 
bore section and the retaining ring decrease the likelihood that the user 
will contact the contaminated top surface of the stopper. 
A further advantage of the present invention is that the user is able to 
readily detect the presence of the potentially hazardous blood specimen on 
the top surface of the stopper. 
A further advantage of the present invention is that the lower annular 
portion of the cap extends beyond the bottom of the stopper to decrease 
the likelihood that the user will contact the contaminated bottom surface 
of the stopper. 
A further advantage of the present invention is that the stopper of the 
present invention may be used with a variety of clinical laboratory 
equipment. 
A further advantage of the present invention is that the design of the 
stopper assists in the proper orientation of the cap on the stopper and 
blood collection tube. 
Yet another advantage of the present invention is that the retaining lips 
on the cap cooperate with the bottom surface of the upper flange portion 
of the stopper to retain the stopper within the cap.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The blood collection assembly of the present invention is referred to 
herein generally as blood collection assembly 10. The blood collection 
assembly 10 consists of a blood collection tube 12, an elastomeric stopper 
14 and a protective cap 16. The blood collection tube 12 is typically 
evacuated to subsequently receive a blood specimen therein. The blood 
collection tube includes an open top end 18, a closed bottom end 20 and a 
cylindrical wall 22 having inner and outer surfaces thereon, 24 and 26, 
respectively. 
The stopper 14 is cylindrical about a centerline or axis illustrated in 
FIG. 1 as reference axis A--A. The stopper 14 is preferably constructed of 
butyl rubber or similar elastomeric materials. The stopper 14 consists of 
an upper flange portion 28 and a lower plug portion 30, wherein the 
horizontal circumference of the upper flange portion 28 is larger than the 
horizontal circumference of the lower plug portion 30 and the top end 18 
of the collection tube 12. An annular groove 32 circumscribes the stopper 
14 along the intersection of the upper flange and lower plug portions, 28 
and 30, respectively, of the stopper 14. The upper flange portion 28 of 
the stopper 14 consists of a generally vertical cylindrical wall 34 and a 
top surface 36 having a top axial recess 38 therein. The top axial recess 
38 preferably tapers downwardly from the top surface 36 to a flat 
diaphragm surface 40 located beyond the vertical midpoint of the upper 
flange portion 28. 
The lower plug portion 30 preferably tapers inwardly and downwardly from 
the annular groove 32 to form a frustoconical surface 42. A further 
frustoconical nose portion 44 extends inwardly and downwardly from the 
frustoconical surface 42 to form the bottom end of the stopper 14. A 
concave diaphragm surface 46 is located inwardly from the frustoconical 
nose portion 44 and extends upwardly approximately one-half of the length 
of the lower plug portion 30. A needle-pierceable diaphragm 48 is formed 
between the flat diaphragm surface 40 and the concave diaphragm surface 
46. 
The cap 16 is generally cylindrical about the centerline or axis 
illustrated in FIG. 1 as reference axis A--A. The cap 16 of the present 
invention is preferably constructed of polypropylene or another semi-rigid 
material. The cap 16 consists of a lower annular portion 50 having a 
plurality of inwardly extending retaining lips 52 thereon and a top 
portion 54 having a centrally located small diameter bore section 56 which 
is surrounded by a downwardly directed retaining ring 58. 
The outer surface of the lower annular portion 50 extends downwardly and 
generally parallel to the outer sidewall surface 26 of the collection tube 
12. In the preferred embodiment, the lower annular portion 50 includes a 
plurality of evenly spaced retaining lips 52 which gradually taper 
inwardly and upwardly along the inner surface of the lower annular portion 
50. As illustrated in the drawings, the retaining lips 52 preferably 
extend intermittently along the inner surface of the annular portion 50. 
The top portion 54 of the cap 16 is generally flat and includes a centrally 
35 located small diameter bore section 56 which is in alignment with and 
allows access to the flat diaphragm surface 40 of the stopper 14. The 
retaining ring 58 surrounds the bore section 56 and extends downwardly 
into the interior of the cap 16 to contact the top axial recess 38 on the 
stopper 14. 
The blood collection assembly 10 of the present invention is designed to 
maintain the evacuated condition of the blood collection tube 12 prior to 
the insertion of the blood specimen, and also to decrease the likelihood 
that laboratory technicians or hospital personnel will be exposed to the 
potentially infectious blood specimens. The stopper 11 of the present 
invention is designed to be inserted into the top end 18 of the blood 
collection tube 12 until the rim of the collection tube 12 is adjacent to 
the annular groove 32. The tapered frustoconical surface 42 of the lower 
plug portion 30 causes the stopper 14 to frictionally fit within the top 
end 18 of the collection tube 12. Once the stopper 14 has been inserted 
into the evacuated collection tube 12, the cap 16 is pressed downwardly 
onto the upper flange portion 28 of the stopper 14. The cap 16 is pressed 
downwardly over the stopper 14 until the retaining lips 52 pass over the 
upper flange portion 28 of the stopper 14 and become aligned generally 
adjacent to the annular groove 32. In this position, the retaining lips 52 
contact the annular surface 53 formed by the bottom of the upper flange 
portion 28 of the stopper 14. Additionally, the retaining ring 58 contacts 
the top axial recess 38 on the stopper 14 as the top axial recess 38 
tapers inwardly and downwardly to the flat diaphragm surface 40. 
The cap 16 of the present invention serves two protective functions. First, 
when the user removes the stopper 14 and cap 16 from the blood collection 
tube 12, the lower plug portion 30 of the stopper 14 has a tendency to 
elongate slightly due to the frictional fit created between the stopper 14 
and the inner sidewall surface 24 of the collection tube 12. The cap 16 of 
the present invention is designed to prevent the separation of the stopper 
14 from the cap 16 when the stopper 14 begins to elongate. In the present 
invention, the resistance caused by removing the stopper 14 from the 
collection tube 12 causes the annular surface 53 at the bottom of the 
upper flange portion 28 to contact the intermittently spaced retaining 
lips 52. 
The second function of the cap 16 is to decrease the likelihood that the 
user will contact the contaminated surfaces of the stopper 14. The small 
diameter bore section 56 and the retaining ring 58 enable the user to 
visually inspect the flat diaphragm surface 40 of the stopper 14 to 
determine whether or not the flat diaphragm surface 40 has been 
contaminated by the specimen. The small diameter bore section 56 and the 
retaining ring 58 also prevent the user from accidentally contacting the 
flat diaphragm surface 40 of the stopper 14 by creating a reduced diameter 
opening to the stopper 14 and ensuring that the flat diaphragm surface 40 
is spaced below the top portion 54 of the cap 16. The lower annular 
portion 50 of the cap 16 extends downwardly beyond the bottom of the 
stopper 14 to protect against accidental contact with the contaminated 
bottom end of the stopper 14. Additionally, the lower annular portion 50 
is designed to decrease the likelihood that the user will be exposed to 
the aerosol of the specimen by forming a protective ring around the top 
end 18 of the collection tube 12 as the stopper 14 is removed from the 
collection tube 12. 
FIGS. 5-7 illustrate a preferred second embodiment wherein the blood 
collection assembly is referred to generally as blood collection assembly 
100. The blood collection assembly 100 of this embodiment includes a blood 
collection tube 102, an elastomeric stopper 104 and a protective cap 106. 
The blood collection tube 102 of this embodiment is preferably a 16 mm or 
larger blood collection tube and includes an inwardly directed annular lip 
108 on the open top end 110 thereof as compared to the cylindrical blood 
collection tube 12 illustrated in FIGS. 1-4 which is typically 13 mm or 
smaller. The blood collection tube 102 also includes a closed bottom end 
(not shown) and a cylindrical wall 114 having inner and outer surfaces 
thereon, 116 and 118, respectively. As with the first embodiment, the 
blood collection assembly 100 of this embodiment is typically evacuated to 
subsequently receive a blood specimen therein. 
The stopper 104 is generally cylindrical and is preferably constructed of 
butyl rubber or similar elastomeric materials. The stopper 104 includes an 
upper flange portion 120 and a lower plug portion 122, wherein the 
horizontal circumference of the stopper 104 gradually increases from the 
lower plug portion 122 to the upper flange portion 120. A first annular 
groove 124 is located approximately midway along the side of the stopper 
104 also includes a further second annular groove 126 spaced above the 
first annular groove 124 approximately midway between the first annular 
groove 124 and the top surface 128 along the upper flange portion 120 of 
the stopper 104. The upper flange portion 120 of the stopper 104 consists 
of a generally vertical cylindrical side surface 127 and a top surface 128 
having a top axial recess 130 therein. The top axial recess 130 preferably 
tapers downwardly and inwardly from the top surface 128 to a flat 
diaphragm surface 132 located slightly beyond the second annular groove 
126 at the approximate midpoint of the upper flange portion 120. 
The lower plug portion 122 of the stopper 104 has an outer diameter which 
is slightly smaller than the outer diameter of the upper flange portion 
120. The bottom surface 134 of the lower plug portion 122 tapers upwardly 
a slight distance from the inner surface to an outer surface adjacent to 
the cylindrical side surface 127 of the lower plug portion 122. The inner 
surface of the bottom surface 134 includes a bottom axial recess 138 which 
tapers upwardly and inwardly to a second generally flat diaphragm surface 
140. The bottom axial recess 138 of the lower plug portion tapers inwardly 
more than the top axial recess 130 to form a lower opening which is 
slightly larger than the top opening in the stopper 104. 
The cap 106 of the second embodiment is preferably constructed of a 
semi-rigid material such as polypropylene and consists of a generally 
cylindrical side surface 142, a substantially flat top surface 144 and an 
open bottom surface. A plurality of inwardly directed retaining lips 148 
are located along the inner surface of the cap 140 approximately three 
fourths of the distance from the bottom surface 146 to the top surface 144 
along the cylindrical side surface 142. In the present embodiment, the 
retaining lips 148 extend inwardly in a generally perpendicularly manner 
from the side surface 142 and the lower end of each retaining lip 148 
tapers upwardly to form a generally flat ledge which contacts and retains 
the stopper 104 within the cap 140. As illustrated in the drawings, the 
retaining lips 148 extend intermittently along the inner surface of the 
side surface 142 of the cap 106. 
The top surface 144 of the cap 106 is generally flat and includes a 
centrally located small diameter bore section 150 which is in alignment 
with and allows access to the flat diaphragm surface 132 of the stopper 
104. A retaining ring 152 surrounds the small diameter bore section 150 
and extends downwardly into the interior of the cap 106 to contact the top 
axial recess 130 on the stopper 104. 
When the blood collection assembly 100 of the present embodiment is 
assembled, the stopper 104 is retained within the cap 106 by retaining the 
upper flange portion 120 of the stopper 104 within the upper section of 
the cap 106. This is accomplished by pressing the cap 106 downwardly on 
the stopper 104 until the retaining lips 148 on the cap 106 contact the 
second annular groove 126 on the stopper 104. The stopper 104 is retained 
on the blood collection tube 102 by the contacting relation between the 
first annular groove 124 on the stopper 104 and the inwardly directed 
annular lip 108 on the open top end 110 of the blood collection tube 102. 
As illustrated in FIG. 5 (and FIGS. 1 and 4), the side surface 142 of the 
cap 106 extends downwardly along the outer surface 116 of the cylindrical 
wall 114 in a generally parallel and slightly spaced apart manner. This 
orientation allows the stopper 104 to be removed from the open top end of 
the blood collection tube 102 without interference from the side surface 
142 of the cap 106. 
In addition to the protective functions described above, the second 
embodiment consistently retains the stopper 104 within the cap 106 by 
creating separate areas for contact between the stopper 104 and the cap 
106 and the stopper 104 and the blood collection tube 102. The retaining 
ring 152 on the cap 140 serves to properly orient the stopper 104 within 
the cap 106 as the blood collection assembly 100 is assembled. 
It is to be understood that various modifications may be made to the 
preferred embodiment without departing from the scope of the invention as 
defined by the attached claims. For example, it is contemplated that the 
retaining ring may be elongated to contact and press against the upper 
flange portion of the stopper to decrease the deformation of the stopper 
as the stopper is removed from the collection tube. Additionally, the 
retaining lips of the present invention may be oriented along the inner 
surface of the lower annular portion of the cap in a variety of shapes and 
sizes as long as there is sufficient contact between the annular ridge and 
the retaining lips to prevent the upper flange portion of the stopper from 
separating from the cap as the stopper is removed from the collection 
tube.