Instrument For Taking Samples From Internal Organs

Abstract

An instrument for taking samples from internal organs of humans and animals in which a cannula for insertion into the organ is detachably connected to a handle portion provided with a plunger pump for drawing the sample into the cannula and a needle of homogeneous material is secured in the pump plunger for axial movement within the cannula and serves to prevent undesired fragments of connective tissues entering the cannula when the cannula passes through the tissues surrounding the internal organ being sampled.

Description

BACKGROUND OF THE INVENTION

This invention relates to an instrument for taking samples from internal organs of human beings and animals.

PRIOR TECHNIQUES

A pathologic change of cells in an internal organ, for example the liver, requires an early and safe diagnosis for allowing the curing of the condition by simple means. Sucn pathologic changes heretofore have been diagnosed by an indirect method, viz. by examining the body liquids secreted from the organ in question. This indirect method, however, did not allow for a sufficiently early diagnosis which was its greatest disadvantage. When using a direct method by taking a small tissue sample from the organ, the diagnosis can be made at a very early stage. For this reason, the direct method was introduced for trial purposes. Due to the absence of an instrument of greater suitability, a usual hypodermic syringe was used and which was provided with a relatively large cannula having an outside diameter of about 2 mm and a conventionally ground down point into which a tissue sample was sucked. The tissue samples thus taken are to a high degree mixed with connective tissues from the tissues surrounding the internal organ in question. For this reason, introduction was made of the method of placing into the cannula a needle of a homogenous material, and removing the needle after the cannula had penetrated through the tissues in front of the organ into the organ. The quality of the sample thus taken was improved, but the sampling technique showed certain disadvantages restricting its application. The large cannula, as a matter of fact, in many cases gave rise to complications in the form of bleedings and infections and was somewhat painful for the patient.

A device for taking samples from internal organs which was developed at a later date utilizes a capillary cannula with an outer diameter of 0.3 - 0.4 mm, the point of which is cut off perpendicularly and ground to a cone angle of 40.degree. - 50.degree. to form a circular edge. With this device, the inconvenience and the risk of complications are at a minimum, and the sample taken, when correctly applying the sampling technique, is substantially free of undesirable connective tissue fragments. The device, however, is not entirely satisfactory since it involves obtaining an accurately adjusted vacuum of about 150 mm water-column for sucking the sample into the cannula. A further objection is that this vacuum has to be connected to a separate pump or suction hose, which has made it relatively difficult to handle the device in practical use.

SUMMARY OF THE INVENTION

The instrument according to the invention provides a complete unit for easy handling, comprising a cannula detachably connected with a handle portion, which includes a plunger pump for drawing the tissue sample into the cannula. By applying the older idea of utilizing a needle of a homogenous material in the cannula in a new, improved manner, the difficulties of accurately adjusting the vacuum are avoided and at the same time the sampling technique is improved and simplified. By securing the needle in the plunger, it draws itself automatically back out of the cannula when the sample is being sucked in, and the sample cannot, by the strong vacuum, be sucked up through the cannula to the pump. The cannula preferably is so designed in accordance with the above mentioned prior art device that the advantages of a capillary canula with its special grinding of the point can be utilized. The outer diameter possibly is to be increased to about 0.5 mm, for preventing the needle from being so thin that it would be uncomfortable to insert the needle into the cannula when the instrument is to be cleaned and sterilized. This increase in diameter by some tenth of a millimeter is so insignificant that it does not imply any disadvantages. The needle diameter is so adjusted in relation to the inner diameter of the cannula that the play therebetween allows the pump to effect sucking through the gap formed, but prevents the tissue sample sucked in to pass the needle. The length of the needle is so adjusted that its free end terminates immediately outside of the cannula mouth when the plunger is in its end position closest to the cannula. When a desired sample quantity has been sucked into the cannula, a pressure balance takes place which interrupts the sucking operation, due to the fact that the plunger on its way exposes a connection to the outer air. The plunger is actuated by a sliding portion on the front part of the handle. The sliding portion is mounted on a cover plate covering a gap, in which a spring clip runs which is secured on the lower surface of the cover plate. The spring clip embraces the plunger in a groove and acts as a carrier. The gap in the pump tube limits the pump stroke. The outer cross-section of the handle can be given a round shape or, which is more advantageous, an angular shape with slightly rounded corners, or it may be given another suitable shape providing a comfortable and safe grip for the hand holding the instrument in the manner of a thick pencil.

In order to avoid the risk of transferring to the patient, for example, infectious yellow jaundice by an unsatisfactorily sterilized cannula, use is made increasingly of throw-away instruments, for example hypodermic syringes, packed in sterile packages and discarded after use. These instruments are assembled of a few simple plastic parts, and as only the cannula is of metal, these instruments are quite inexpensive. The principle can be applied alternatively to an instrument according to the invention. The instrument in such case can be manufactured to be of the throw-away type in its entirety, or it may be sufficient to manufacture only those instrument parts for discard which are to be inserted into the body tissues, i.e. the cannula and the needle. The invention is designed so as to allow for a rapid and simple mounting and dismounting of the cannula and needle.

A preferred embodiment of the instrument is described in greater detail in the following, with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of longitudinal section through the instrument, with the plunger being in its forward position,

FIG. 2 is a view taken along the line II-II in FIG. 1, the view looking in the direction of the arrows,

FIGS. 3 and 4 are fragmentary views showing details of the front part of the cannula on an enlarged scale with the needle controlled by the plunger, in which FIG. 3 shows the needle position when the plunger is fully inserted, and

FIG. 4 the needle position when the plunger is fully retracted, and

FIG. 5 is a fragmentary view illustrating the manner in which the needle is secured in the plunger.

DETAILED DESCRIPTION OF THE INVENTION

The instrument shown in FIG. 1 comprises a tubular body defining an elongated pump tube 1 having a hexagonal outer cross-section with slightly rounded corners, FIG. 2, so as to provide a safe and comfortable grip for the hand. The grip is improved in that the forward portion of the pump tube 1 is knurled. In the forward portion of the pump tube 1 is movably arranged a long plunger 2 provided with a sealing ring 4 mounted in a groove 3 in the plunger. The plunger 2 is actuated by a finger portion 5 on a cover plate 6 which is connected with the plunger 2 by a spring clip 7 embracing a groove 19 in the plunger 2. A slot 8 for the spring clip 7 is provided in the pump tube 1 and limits the length of the pump stroke. An aperture 9 in the pump tube 1 connects the interior of the pump tube 1 with the outer air and brings about a pressure balance immediately prior to the arrival of the plunger 2 at its retracted end position, when the aperture 9 is exposed after a sufficiently great tissue sample has been sucked into the instrument. The rearward portion of the pump tube 1 is closed by a rounded plug 10, and the forward portion of tube 1 is designed as a reduced end piece 11 having an axial through bore and a gasket 12. On the forward portion of the end piece 11, a quick-coupling 13 of a bayonet type serves to detachably connect a capillary sampling cannula 14 to the end piece. The cannula 14 has a pointed end 15, FIGS., 3 and 4 which preferably is ground conical to form a sharp circular edge, but it also may have another suitable form (not shown). In the plunger 2, a needle 16 of a homogeneous material is fastened and the needle extends through the axial bore in the end piece 11 and the cannula 14 and terminates in a point 17. The point 17 extends immediately outside of the pointed end 15 of the cannula 14 when the plunger 2 is in its inner end position (FIG. 3). The diameter of the needle 16 is so adjusted in relation to the inner diameter of the cannula 14 as to form a narrow gap 18 therebetween, which, during the pumping operation, allows for a pressure balance between the cannula 14 and the interior of the pump tube 1, but which is sufficiently narrow to prevent the tissue sample taken from passing past the point 17 of the needle (FIG. 4).

For enabling a rapid exchanger or replacement, the needle 16 is mounted detachably in the plunger 2, and more specifically, the plunger 2 is provided with an axial cylindrical hole 20, the forward portion or mouth of which is widened to provide a conical guide 21 for a twice-folded resilient holder 22 of the needle 16. Upon mounting the needle 16, the resilient holder 22 is moved in the direction of the arrow against the plunger 2 with the insertion into the hole 20 being facilitated by the guide 21. The needle 16 having reached the bottom of the hole 20, is resiliently secured in the plunger 2. The force of resilience is sufficient for the needle 16 to participate in the movements of the plunger 2, but the force is such that the needle easily can be withdrawn from the hole 20 for exchange purposes. The length of the needle 16 is so adjusted that it projects after mounting, some distance outside of the pointed end 15 of the cannula 14. This piece is cut off to align with the pointed end 15.

Before sampling, it is desirable to make certain that the joints between the end piece 11 and the quick-coupling 13 and between the quick-coupling 13 and the cannula 14 respectively are tight. This can be simply effected by sucking up into the instrument, a liquid innocuous to the body tissues, for example a sterile isotonic saline solution which thereafter is sprayed out of the instrument. The liquid residue remaining in the gap 18 and in cavities behind the gap does not disturb the sampling, but acts as an additional barrier, not necessary per se, when thee instrument passes through the tissue in front of the organ in question.

The instrument is then held similar to a pencil with one finger on the sliding portion 5, which is held in its forward position while the cannula 14 is inserted through the tissue surrounding the organ until the pointed end 15 reaches the sampling area in the internal organ. The plunger 2 is slowly retracted by means of the sliding portion 5 at the same time as the cannula 14 is inserted an additional short distance whereby a tissue sample is sucked into the forward portion of the cannula 14 in front of the returning needle 16. When the plunger 2 exposes the aperture 9, the vacuum in the instrument is balanced, and the suction of the tissue sample is completed. The instrument can now carefully be pulled out while the plunger 2 still is in its retracted position. The sample then removed from the cannula 14 for examination by moving the plunger 2 to its forward position.

The design of the individual parts as well as the choice of the construction material can be varied to a substantial degree without departing from the basic idea of the invention. It can be imagined, for example, to manufacture the instrument of metal and/or glass, with a constructional design which is suitable in such a case, not the least in consideration of a repeated use of the instrument, or the instrument can be given a highly simplified design, with most of the details made of plastic, when the instrument is intended to be discarded after use.

Claims

We claim:

1. An instrument for taking tissue samples from internal organs of humans and animals comprising a tubular body having an open end and a closed end, a plunger mounted for axial movement within the body, said body and plunger constituting a vacuum pump, with said body also serving as a handle for the instrument, a cannula constituting a sampling portion of the instrument, said cannula having an outer diameter of about 0.4 mm, means detachably connecting the cannula to the open end of the body, a needle of homogeneous material, means resiliently supporting the needle in the plunger, said needle extending through the open end of the body into the cannula and terminating in a point located immediately outside the end of the cannula when the plunger is at the end of its stroke towards the open end of the body, the outer diameter of the needle and the inner diameter of the cannula being such as to provide a narrow annular gap between the needle and cannula, said gap allowing for a pressure balance between the cannula and the body upon movement of the plunger from the open end toward the closed end of the body yet preventing the passage of the tissue sample past the point of the needle during the movement of the needle with thee plunger, said body having an axial slot therein, means attached to the plunger and projecting through said axial slot, a member slidably mounted on the outside of said body to which said attaching means is secured, the length of the axial slot limiting the stroke of the plunger, and said body having an aperture in proximity to the open end of the body to provide communication between the body and the outer air, said aperture being closed when the plunger is adjacent the open end of the body but being exposed when the plunger moves toward the end of its stroke in the direction of the closed end of the body after a tissue sample has been drawn into the cannula to effect the pressure balance.

2. The instrument according to claim 1, characterized in that said attaching means is a spring clip and said slidably mounted member is a cover plate.

3. The instrument according to claim 1, characterized in that the resilient supporting means for the needle comprises a twice-folded resilient holder and an axial cylindrical hole in the plunger having a widened mouth to form a conical guide into which the holder may be inserted and removed.