EP0814727B1

EP0814727B1 - Trans-cervical infusion pipette

Info

Publication number: EP0814727B1
Application number: EP96945684A
Authority: EP
Inventors: Manuel P. Botelho
Original assignee: MAI GENESIS IND Inc; MAI/Genesis Industries Inc
Current assignee: MAI/GENESIS INDUSTRIES Inc
Priority date: 1995-12-18
Filing date: 1996-12-18
Publication date: 2002-05-29
Anticipated expiration: 2016-12-18
Also published as: EP0814727A1; CA2213252A1; DE69621433D1; DE69621433T2; ATE218051T1; WO1997022309A1; CA2213252C; AU1690197A

Abstract

Pipettes for infusing the uterus are disclosed, each pipette being generally comprised of a proximal end, a mid-section and an enlarged distal tip. The proximal end has a coupling portion for engagement with a fluid-expressing syringe. Distal tips disclosed are of two primary shapes, one having a generally hemispherical distal zone of expanding diameter in a distal to proximal direction; and, another having a generally frusto-conical distal zone, with a similary expanding diameter. Each tip also has a frusto-conical proximal zone, decreasing in diameter in a distal to proximal direction. One embodiment includes a generally cylindrical medial zone between its distal and proximal zones. The method of the invention includes using a guide hand in the anal canal above the cervical area to align the enlarged distal end of the pipette with the cervix; driving the pipette through the cervix until a decrease in resistance is sensed; and then, pulling back on the pipette such that its enlarged distal tip effects a sealing action against the rim of the inner cervical opening. Once the fluid is infused into the uterus, the pipette is withdrawn.

Description

BACKGROUND OF THE INVENTION 1. Field Of The Invention

The present invention relates generally to the veterinary arts, and more specifically to devices for inseminating and infusing medicines into the uteri of large female farm animals such as cows and mares.

2. Description Of The Related Art

Those who tend to the care and breeding of livestock such as cattle and horses frequently have a need to infuse semen, medicine or other fluids into an animal's uterine cavity. The instrument commonly used for this purpose is a straight, tubular, plastic pipette from 18 to 22 inches (45 to 56 cm.), or so, in length connected to a proximal, fluid-expressing syringe. That is, the distal end of the standard infusion pipette is of the same diameter as the rest of the pipette along its length, and that end is simply squared off at a right angle to the pipette's long axis. In other words, this standard pipette's distal end is square when viewed in longitudinal cross section.

(Note that the complementary terms "distal" and "proximal" used herein for orientation refer to the instrument of the invention, rather than, as is the convention in the veterinary arts, to the animal.)

Although product literature commonly describes these standard pipettes as having "smooth, rounded, polished ends," experience proves that pipette tips remain quite sharp and able to injure an animal if not used with the utmost care.

Standard infusion procedure includes, first, extending a hand and arm into the animal's rectal canal and, by sense of touch with the fingertips of this "guide hand" through the combined thicknesses of the rectal and vaginal walls, guiding the narrow distal tip of the standard pipette up to the threshold of the cervical opening. Then, while grasping the animal's muscular cervical cylinder in the fist of the guide hand, through the rectal sheath, and trying to align its narrow axial channel with the pipette's length, and while, at once, manipulating the semi-rigid pipette's proximal end some eighteen inches, or more, away from its distal tip, thrusting it carefully but firmly to and fro, one attempts to guide that narrow tip into the cervical opening. This procedure is not unlike attempting to thread a needle at arm's length with one's eyes closed.

However, even when this procedure is carried out by a highly experienced animal tender, such squared-off, frequently sharp-edged pipette tips commonly cause trauma to the vaginal canal and, more importantly, to the cervical opening and surrounding tissues. Any trauma in this area creates a high risk of infection, thus threatening the animal's overall health and perhaps its ability to breed again quickly. And, when the trauma is at the cervix or in the uterus it can threaten an animal's future ability to breed, altogether, or may even be fatal.

Even when healthy and noninfected, guiding the standard square-tipped pipette safely into and through the cervical passage requires considerable skill. Indeed, horse and cattle tenders with sufficient training and experience to infuse an animal quickly, safely and reliably in a high-volume breeding operation usually draw considerably higher wages than those who either require more time to perform the operation, or who do so less-reliably. But, precision and skill are even more critical when medicinal infusion of an already-infected animal is attempted with the standard, square-tipped pipette. In that case, the tissues of the cervical opening and passage are swollen, tender and inflamed, making the animal even more sensitive and potentially very uncooperative during treatment. And, whether tending to an infected animal or a healthy one, an animal tender lacking infusing experience can easily drive a pipette tip directly into its vaginal or cervical flesh, embedding it therein, and then discharge the attached syringe's contents, without realizing the highly injurious mistake.

Irritation or injury to an animal's vaginal, cervical and/or uterine areas can cause several reflexive reactions that make completion of the infusion procedure much more difficult, and perhaps even dangerous to an animal tender. One common reaction is constriction of the animal's strong rectal and vaginal muscles upon the animal tender's arms and hands, which can, at least, limit the tender's dexterity. Another is that cervical area pain tends to cause an animal to hunch its back, thus directing its vaginal and anal canals downward and causing the tender to resort to an awkward, uncomfortable stooped position while attempting to continue the infusion procedure. Animals having this kind of pain also tend to kick, and to step and thrash side-to-side, which exposes a tender to crushed feet and other types of severe injury.

Although they continue to be virtually exclusively used in carrying out artificial insemination, square-tipped pipettes are also at the root of several problems that arise during that specialized type of infusion procedure. Injury of the aforedescribed type is one drawback, but failed delivery into the uterus of some or all of the often very expensive semen is another. Such failure can occur when the cervical opening is missed with the pipette's tip, and the attached syringe's contents are spilled into the vaginal cavity, thus significantly reducing the likelihood of conception. Even when the pipette tip is successfully guided through the cervical passage and into the uterus, leakage can occur as discharged semen flows back, under uterine pressure, through the space between the sides of the pipette and the walls of the cervical channel. And, even when the cervical opening is successfully located and the pipette's tip is driven into the uterus as planned, such tips can abrade or otherwise traumatize the uterus, thus greatly reducing the likelihood of successful implantation of a zygote in the uterine wall, if, indeed, fertilization occurs at all. This can happen very easily because with a thin, tubular pipette of uniform diameter, there is no tactile signal when the pipette's tip has reached and gone beyond the inside end of the cervical canal. That is, there is nothing to indicate when the pipette has been driven in too far and its tip is beginning to traumatize the uterine lining.

This lack of a tactile signal upon proper insertion and placement of the pipette tip is also a problem during medicinal infusion, when the end of a straight-tipped pipette can be driven too far through the cervix, and into one or the other of the uterine horns. If the medicine is expressed from the pipette tip too far into one horn or the other, even disbursement thereof throughout the entire uterus is much less likely, and medical consequences could result. Again, highly experienced animal tenders can reduce that risk by their fine sense of touch and their ability to direct the infused medicinal fluid into the proper part of the uterus, even when using a straight-tipped pipette. But, these experts demand a wage commensurate with the superiority of their skills.

Thus, it appears that a need exists for an instrument for easily, quickly, efficiently and precisely infusing and inseminating large farm animals without injuring an animal's vaginal, cervical or uterine tissues.

EP 0148473 describes a pipette arrangement having an enlarged end region. The enlarged end has a flat leading surface but no sharp comers.

SUMMARY OF THE INVENTION

The trans-cervical infusion pipette of the present invention is adapted to overcome the above-noted shortcomings and to fulfill the stated needs.

According to the present invention there is provided a pipette comprising an elongate tubular portion having a proximal end and a distal end, the distal end being provided with a distal tip of enlarged form, the distal tip having a distal zone and a proximal zone, the proximal zone being angled at about 9° relative to the axis of the pipette such as to effect a good sealing action against the backflow of fluids from the uterus into the cervix.

A pipette so shaped is much easier to guide through the vaginal canal, and to align with the cervical opening, without causing any trauma. Further, it is easier to push through the cervix into the uterus without trauma to either; and, once pushed through, it can be manipulated to minimise leakage of the infusion back through the cervical canal.

Thus, it is an object of the present invention to provide an infusion pipette better suited to preserving an animal's health than is possible with the currently-used square-tipped pipette.

It is a further object of the present invention to provide an infusion pipette which is so much easier to use, that a less-experienced, lower-paid animal tender can infuse an animal's uterus with medicine or semen as quickly and as safely as a more experienced, higher-paid animal tender.

Still further objects of the inventive infusion pipette disclosed herein will be apparent from the drawings and following detailed description thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the trans-cervical infusion pipette of the invention engaged with its syringe.

FIG. 2 is a top, partially transparent view of a large animal's vaginal canal laid open, showing an animal tender's arm inserted in the anal canal (not shown) above the plane of the vaginal canal, wherein the animal tender's hand is grasping the underlying cervical cylinder from the anal canal, and guiding the infusion pipette of FIG. 1 through the cervix.

FIG. 3 is a perspective view of the distal tip of a pipette adapted for use in infusing the uterus of a cow.

FIG. 4 is a cross-sectional view of the distal tip of the pipette shown in FIG. 3.

FIG. 5 is a perspective view of the distal tip of a pipette adapted for use in inseminating, or infusing the uterus of, a mare.

FIG. 6 is a cross-sectional view of the distal tip of the pipette shown in FIG. 5.

FIG. 7 is an enlarged cross-sectional view of the inner cervical orifice showing the tip of the pipette of FIG. 1 in the uterus and pulled backward into a sealing, seated position against the rim of the inner cervical orifice.

FIG. 8 is a cross-sectional view of an alternative embodiment of a cow pipette of the invention engaged with apparatus for expressing sperm therefrom.

FIG. 9 is a fragmentary cross-sectional view of an alternative embodiment of the pipette of FIG. 4 for use with the sperm-expressing apparatus of FIG 8.

FIG. 10 is a fragmentary cross-sectional view of an alternative embodiment of the pipette of FIG, 6 for use with the sperm-expressing apparatus of FIG 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now specifically to the drawings, FIGS. 1 through 4 show one embodiment of the inventive pipette, specifically, one that is especially adapted for use in the procedure of infusing a cow's uterus with medicated fluid, this cow-specific embodiment being generally identified herein with the reference numeral 10. Cow pipette 10 has a proximal end 12, a mid-section 14 and a distal tip 18.

Proximal end 12 is engageable with a common fluid-expressing syringe 16 of the type normally used for infusing cows. Syringe 16 is preferably able to contain 60 cc.'s of fluid, or so.

Cow pipette 10 is approximately 53 cm. long from proximal end 12 through distal end 16. Pipette 10 has an outside diameter of approximately 5.0 mm., an inside diameter of 3.0 mm., and a wall thickness of approximately 1.0 mm. Proximal end 12 may include an endmost coupling region 20 which has a slightly larger inside diameter of 4 mm., or so. This short, larger-diameter coupling region 20 functions in mating syringe 16 to pipette 10. Coupling region 20 extends about 5 mm. in from pipette 10's proximal terminus, and ends at an interior circumferential ridge where, from there on through distal tip 16, pipette 10's inside diameter is approximately 3 mm.

Pipette 10 is preferably constructed of relatively rigid, transparent plastic. However, in the aforedescribed preferred dimensions, pipette 10 has considerable lateral, resilient flexibility; thus, it is easy to bend, but when released, it readily springs back to a straight configuration.

Polyvinyl chloride ("PVC") is presently the material of choice in cow pipette 10's construction. But, other materials now known or later discovered may also work as well. For example, polycarbonate, polyethylene and such other plastics as are known in the art to have the desired properties, and to be suitable for medical-type applications, may work satisfactorily in carrying out the invention.

Distal tip 18 has a larger diameter than the rest of pipette 10. The overall length of enlarged tip 18 is approximately 22 mm., that being the distance between its distal-most terminus 22 and the distal-most extent of the directly proximally-adjacent, 5 mm. diameter mid-section 14.

The shape and dimensions of distal tip 18 are important for the best function of the invention and, as set forth more fully below, they are the reason for many of the unexpected benefits described herein. The preferred shape and dimensions of tip 18 were arrived at empirically. Experimental trials were conducted with various hand-made prototype pipettes having different tip shapes and sizes, and the tip performing best, overall, was chosen as the preferred embodiment.

As a pipette's tip is preferably rotationally symmetrical about the pipette's primary axis, a tip's shape is most conveniently expressed in terms of its diameter at points along its length. Thus, beginning at the distal-most terminus 22 of the experimentally-derived preferred prototype for a cow infusion pipette tip 18, and proceeding in a proximal direction therefrom in consecutive 2.0 mm. increments along primary axis 24, the measured diameter at each increment is as shown in Table I.

Generally, it can be seen from drawing FIGS. 3 and 4, that cow pipette tip 18 has a first, distal-most zone 26 which is approximately hemispherical, having a radius of about 4 to 5 mm., or so. Following this, a medial second zone 28, which is roughly cylindrical and 9-10 mm. in diameter, extends for another 4 mm., or so. Finally, a proximal third zone 30, some 14 mm. long and having a frusto-conical shape at roughly 9 degrees to axis 24 (see angle "A"), narrows toward an integral union with the 5 mm. diameter, cylindrical mid-section 14 of pipette 10.

Tip 18's inside diameter at terminus 22 is 3 mm., just as through the rest of tip 18 and mid-section 14, right. up to coupling region 20. Thus, tip 18 is solid throughout and integral with the rest of pipette 10, and no cavity or larger inside diameter portion is included therewithin.

The conclusion as to distal tip 18's optimum shape and dimensions in first, second and

third zones

26, 28 and 30, respectively, resulted from trials and qualitative observations, with a focus on several goals. These include: making the tip large enough in diameter for easy tactile location and manipulation by the user, even through tissue layers of the thicknesses encountered when infusing a cow, yet making the tip narrow enough to minimize the constricting, hunching and thrashing reactions of the animal upon attempting to drive the pipette tip through the cervix 32 to the uterus 34; keeping the pipette tip blunt enough to prevent injury to the vaginal 36, cervical 32 and uterine 34 tissues, but not so blunt as to impede its passage though the cervical canal 38; and, assuring that the overall length of the pipette tip is such that, once it is driven fully into the uterus and pulled back to seat against the inside of the cervix, as shown in FIGS. 2 and 7, the tip's distal terminus 22 does not project so far as to cause the infused fluid to be directed into one horn 40 of the uterus to the exclusion of the other.

The foregoing functional objectives are met, primarily, by the shape and dimensions of pipette tip 18's distal and medial first and second zones, 26 and 28, respectively. First zone 26's generally hemispherical configuration, in the stated dimensions, was also chosen for its tendency to "self-locate" the pipette tip 18 at the outer cervical opening 42, thus avoiding the prior problem of the pipette tip being deflected into the circular fold of softer vaginal flesh surrounding the more muscular, protruding, quasi-cylindrical tip of the cervix.

The distance terminus 22 projects into uterus 34 once tip 18 is seated against the inside of the cervix is also affected by the angle of taper of tip 18's surface in its proximal third zone 30. A steeper angle would cause distal end 22 to project too far. Yet, a shallower angle would not provide one of the more important functional benefits of the inventive pipette's tip 18, that being that it provides the user with a clear tactile signal when it is seated properly against the inside rim 44 of the cervix. Specifically, upon insertion, resistance is felt as the pipette's tip is driven in a distal direction through the cervix. However, once tip 18 clears the cervix and emerges fully into the uterus (this forward-most tip position being indicated with reference numeral 46 as shown in phantom in FIG. 2) a distinct decrease in resistance is felt because, at that point, the cylindrical mid-section 14 of pipette 10 begins to slide telescopically very easily to and fro in the cervical channel. (This tangible reduction of resistance at a discrete point in the distally-directed motion is useful in avoiding possible uterine trauma from driving tip 18 too far forward and against the uterine wall.) Then, upon pulling back on pipette 10, i.e. in a proximal direction, the point at which relatively resistance-free motion ceases and a resilient tension against further proximal movement is felt is the point at which tip 18 is properly seated against the inside rim 44 of the cervix for infusion.

The angle of taper of tip 18's surface in third zone 30 also affects the quality of the seal against backflow of infused fluid in response to infra-uterine pressure. Too steep an angle would cause less of zone 30's surface area to be in contact with the muscular inner cervical rim 44. In contrast, a shallower angle might cause more of zone 30's surface to be in contact with the lining of the cervical canal, but if too shallow, the pressure therebetween might not be sufficient to effect an efficient seal. Thus, the approximate 9 degree slope of zone 30 with respect to axis 24, and zone 30's approximate 14 mm. length, have been found to be the optimum for safe, quick and positive cow infusion.

All of the foregoing considerations, both structural and functional, may be affected by differences in size, health, musculature, resilience and surface condition of each particular animal's organs. Lubrication (both natural, and applied) is yet another variable. However, pipette 10, and especially tip 18, as described herein are shaped and dimensioned for general use in infusing the great majority of cows of breeding age.

As suggested above, the infusion method is an improvement upon the standard method in that the enlarged pipette tip permits addition of several safety and efficiency-enhancing steps thereto. One such step is locating the enlarged pipette tip with the guide hand from the overlying anal canal to assure that the tip is properly positioned for insertion into the cervical channel. The self-locating tendency of tip 18, because of its shape, may make this locating step unnecessary for some experienced users; but, the palpable assurance that tip 18 is poised at the outer cervical os ready for insertion may be one factor in permitting less-experienced animal tenders to perform infusion safely and effectively.

Another important step in the method is driving the enlarged pipette tip gently through the cervix until a distinct reduction of resistance is felt, that being the point at which the tip emerges fully into the uterine cavity. Yet another, following this, is pulling back on the pipette to a point at which relatively resistance-free motion ceases and a resilient tension against further proximal movement is felt. This is the point at which the pipette tip is properly seated against the inside rim of the cervix to effect a seal against leakage back down the cervical channel. This sealing action may be enhanced by using some constrictive hand pressure around the cervical cylinder with the guide hand. These forward and then seated positions with respect to the guide hand are generally indicated in FIG. 2.

Once the distal tip is in the seated position in the interior cervical opening, the desired fluid is expressed into the uterus. Of course, once the fluid is infused into the uterus, the pipette is withdrawn.

Yet another embodiment of the inventive pipette is herein disclosed, this being adapted specifically for inseminating and cervically infusing mares, and being generally identified herein with the reference numeral 48. Mare pipette 48 has a shape and dimensions somewhat different from those of cow pipette 10. However, these differences are confined solely to pipette 48's distal tip 50, and are dictated by all of the considerations of structure and function articulated above with respect to a cow but, in this instance, as applied to the anatomy of a mare. Thus, the proximal end 12, mid-section 14 syringe portion 16, and coupling region 20 of pipette 48 are identical with those of pipette 10 for these explanatory and exemplary purposes. And, the method of use is the same, as well.

Distal tip 50 has a larger diameter than the rest of pipette 48. The overall length of enlarged tip 50 is approximately 38 mm., that being the distance between its distal-most terminus 52 and the distal-most extent of the directly proximally-adjacent, 5 mm. diameter mid-section 14.

As above, beginning at distal-most terminus 52 of mare infusion pipette tip 50, and proceeding in a proximal direction therefrom in consecutive 2.0 mm. increments along primary axis 54, the measured diameter at each increment is as shown in Table I.

Generally, it can be seen from drawing FIGS. 5 and 6, that mare pipette tip 50 has a first, distal-most zone 56 which is approximately 8 mm. long and frusto-conical, such that tip 50's diameter increases in a distal to proximal direction at approximately 33 degrees to axis 54. See angle "B." Following this, a short, transitional second zone 58, which is roughly 14 mm. in diameter extends for another 2 mm., or so. Finally, a proximal third zone 50, some 28 mm. long and having a frusto-conical shape at roughly 9 degrees to axis 54 (see angle "C"), narrows toward an integral union with the 5 mm. diameter, cylindrical mid-section 14 of pipette 10.

As in cow pipette 10, tip 50's inside diameter at terminus 52 is 3 mm., just as through the rest of tip 50 and mid-section 14, right up to coupling region 20. Thus, tip 50 is solid throughout and integral with the rest of pipette 10, and no cavity or larger inside diameter portion is included therewithin.

As with cow pipette 10's tip 18, mare tip 50's abilities in eliminating problems in the insertion procedure are primarily a function of the diameter and slope of the tip's distal portion, while providing a good seal against leakage of the infused fluid from the uterus, once the tip is pulled back into a seated position against the inside of the cervix, is primarily a function of the diameter and slope of the tip's proximal portion.

As shown in FIGS. 8, 9 and 10, pipettes in accordance with the invention are also envisioned for use with standard insemination apparatus. FIG. 8 shows such a cow pipette 62, along with insemination apparatus 64 including rigid metal sleeve 66 with flared proximal portion 67 and proximal hub-like handle 68; retaining ring 70; rigid plunger rod 72 with proximal disc-shaped handle 74; and, semen-containing straw 76. Pipette 62 includes a proximal end 78, an elongate mid-section 80 and an enlarged distal tip 82.

Proximal end 78 and mid-section 80 of pipette 62 have a continuous lumen 84, wherein lumen 84 has an inside diameter dimensioned for sliding receipt of rigid sleeve 66. Proximal end 78 of pipette 62 expands slightly upon receipt of flared proximal portion 67 of rigid sleeve 66. Pipette 62 is locked frictionally to sleeve 66 by retaining ring 70 which fits snugly and securely on flared portion 67, binding proximal end 78 of pipette 62 thereto.

Sleeve 66 projects through lumen 84 up to, or closely adjacent to, a constriction which may be in the form of a first step 86, beyond which lumen 86 has a first decreased-diameter portion 88. First step 86 is preferably adjacent to or within tip 82 of pipette 62, so that the stiffening function of sleeve 66 ties pipette 62's mid-section 80 and tip 82 together into a single rigid structure.

First decreased-diameter portion 88 is preferably dimensioned for sliding receipt of semen-containing straw 76. And, first decreased-diameter portion 88 is preferably slightly tapered toward its distal extent, said tapered portion being generally identified herein with reference numeral 90. Tapered portion 90 is preferably dimensioned such that when the sealed distal end of semen-containing straw 76 is cut off and straw 76 is inserted, distal end first, into the proximal end of sleeve 66, straw 76 can be driven distally to a point where its distal end will lodge securely at or closely adjacent to the distal extent of tapered portion 90. A second step 92 at the distal extent of tapered portion 90 helps assure that straw 76 cannot be driven further in a distal direction. Beyond second step 92, a second decreased-diameter portion 94 forms the distal end of lumen 84. The distal end of second decreased-diameter portion 94 is the opening in the rounded, distal-most surface of distal tip 82.

Straw 76 is driven distally through sleeve 66 by inserting the distal end of rigid plunger rod 72 into sleeve 66 behind straw 76. Straw 76 includes an open proximal end fitted with fibrous plug 96. The diameter of rigid plunger rod 72 is such that its distal end fits into the proximal end of straw 76, behind fibrous plug 96. The length of rigid plunger rod 72 is such that when it is driven in a distal direction behind fibrous plug 96 by distally-directed pressure on the proximal face of disc-shaped handle 74, disc-shaped handle 74 seats against the proximal side of hub-like handle 68 as the distal end of rigid plunger rod 72 reaches the distal end of semen straw 76. Rigid plunger rod 76 should not be so long that it is able to push fibrous plug 96 beyond straw 76's distal end.

As plug 96 is driven to the distal end of semen-containing straw 76, the semen therein is expressed from the end of straw 76, through second decreased-diameter portion 94, and out of the central opening in pipette 62's distal tip 82. Such axial expression of the semen assures that it suffers the least damage from the shear forces generated in its movement out of straw 76 and into the uterus.

FIGS.. 9 and 10 show cow and

mare pipettes

62 and 98, respectively, for use with standard insemination apparatus 64. However, FIGS. 9 and 10 show only pipettes 62 and 98 to better illustrate their structures.

To further limit the likelihood of trauma to the cervix or uterus from rough surfaces on a trans-cervical pipette constructed in accordance with the invention, it is also preferable that a pipette include a smoothly rounded rim 100 around the distal opening of lumen 84 at distal tip 82. That is, a smooth, seamless surface should be present between, and integral with, the inner surface of the pipette which defines lumen 84 and the outer, distal-most surface of the pipette's tip. Such rounded rims 100 are shown in the pipettes of FIGS. 9 and 10.

The foregoing detailed disclosures of the

inventive pipettes

10 and 48, and their

respective tips

18 and 50, are considered as only illustrative of the preferred embodiments of, and not a limitation upon the scope of, the invention. Those skilled in the art will envision many other possible variations of the structures disclosed herein that nevertheless fall within the scope of the following claims. For example, a more frusto-conical than hemispherical shape in tip 18's distal first zone 26 may not be optimum, but may be satisfactory in some instances. Indeed, angles there of 10 to 60 degrees or more with respect to axis 24 could conceivably be employed. The overall maximum diameter of tip 18 may also vary a bit, especially if being adapted to infusing particularly large or small animals. The angles "B" and "C" employed in the corresponding zones of mare pipette 48, as well as its overall dimensions, may be varied similarly to suit particular needs. Thus, although the shapes and dimensions disclosed herein are considered optimum for general use on cows and mares, changes can be made, as necessary, without departing from the invention.

With regard to the method of the invention, in particular, the overall shape and dimensions ofthe pipette tip used are not critical, as long as the distal tip has an enlarged diameter in comparison with the rest of the pipette's length. All that is necessary for the method is that the enlarged tip be of a sufficiently small diameter to fit through the cervix without trauma or extreme discomfort, and to be of a sufficiently large diameter to lodge sealingly in the inner cervical orifice (perhaps with a bit of constricting pressure on the cervical cylinder with the guide hand), such that the tip's distal-most terminus protrudes a bit into the uterus. Thus, it is certainly desirable, but not critical to the method, that the pipetre's distal tip be shaped as disclosed herein. As long the tip is larger than the proximal portions of the pipette, the method can be practiced more or less effectively.

And, alternative uses for these inventive pipettes may later be realized. For example, infusion of other animals such as sheep, goats and swine may be facilitated with some of these disclosed structures or methods. And, infusion of animals of vastly different sizes than those disclosed herein may be made easier by application of these general principles. Accordingly, the scope of the invention should be determined with reference to the appended claims, and not by the examples which have herein been given.

distance from distal terminus (mm.)	circum. of cow pipette (mm.)	circum. of horse pipette (mm.)
0	5.0	5.0
2	8.0	8.8
4	9.7	11.6
6	9.7	13.9
8	9.2	14.3
10	8.8	13.9
12	8.2	13.0
14	7.6	12.6
16	6.9	12.0
18	6.3	11.3
20	5.7	10.7
22	5.0	10.1
24		9.5
26		8.8
28		8.2
30		7.9
32		6.9
34		6.3
36		5.7
38		5.0
TABLE I. Diameters of distal tips of cow and horse infusion pipettes were measured in consecutive 2.0 mm. increments, beginning from their distal-most termini.

Claims

A pipette for infusing fluid into a uterus or an insemination pipette, the pipette comprising an elongate tubular portion (14) having proximal and distal ends, the distal end of the elongate tubular portion being provided with an enlarged distal tip (18, 50, 62, 98) for indicating when the distal end emerges from the cervix into the uterus, wherein the distal tip (18, 50, 62, 98) is shaped to include a distal zone (26, 56) and a proximal zone (30, 60) and characterised in that the proximal zone (30, 60) is angled at approximately 9° relative to the axis of the elongate portion (14) to effect a good sealing action against the backflow of fluids from the uterus into the cervix.
The pipette of Claim 1, further including means for indicating when said pipette is being driven too far into said uterus.
The pipette of any one of the preceding claims, wherein said distal zone (26, 56) has an expanding diameter in a distal to proximal direction, said proximal zone (30, 60) having a decreasing diameter in a distal to proximal direction.
The pipette of Claim 3, wherein said distal and proximal zones (26, 56, 30, 60) are contiguous with one another through a medial zone (28, 58) therebetween.
The pipette of Claim 4, wherein said medial zone (28, 58) is generally cylindrical and/or said distal zone (26, 56) is generally hemispherical or frusto-conical in shape and/or wherein said proximal zone (30, 60) is generally frusto-conical in shape.
The pipette of Claim 5, wherein said pipette has an elongate, primary axis and wherein said distal zone (26, 56) is sloped at an angle of between approximately 10 and 60 degrees with respect to said axis, roughly 33 degrees, between 5 and 50 degrees with respect to said axis, or roughly 9 degrees.
The pipette of any one of the preceding claims, wherein said distal tip (18, 50, 62, 98), at consecutive 2 mm. increments from its distal-most terminus has diameters of approximately: 5.0, 8.0, 9.7, 9.2, 8.8, 8.2, 7.6, 6.9, 6.3, 5.7 and 5.0 mm. or 5.0, 8.8, 11.6, 13.9, 14.3, 13.9, 13.0, 12.6, 12.0, 11.3, 10.7, 10.1, 9.5, 8.8, 8.2, 7.9, 6.9, 6.3, 5.7 and 5.0 mm.
The pipette of any one of the preceding claims wherein said enlarged tip has a rounded distal-most surface; said pipette further having:

a. an opening (94) in said rounded, distal-most surface of said tip;

b. an axial, continuous lumen (84) from said proximal end, through said elongate portion, through said enlarged tip and contiguous with said opening (94);

c. means (90, 92) for retaining a semen straw within said lumen.
The pipette of Claim 8, wherein said elongate portion includes means for receipt of a rigid sleeve.
The pipette of Claim 9, wherein said sleeve receipt means includes a lumen of greater diameter from said proximal end of said elongate, cylindrical portion, up to a constriction (86) within or closely adjacent to said enlarged tip, said lumen between said constriction (86) and said opening being of a diameter which is less than that between said proximal end and said construction (86).
The pipette of Claim 10, wherein said semen straw retaining means (90, 92) comprises a portion (90) of said lumen between said constriction (86) and said opening wherein said lumen has a further reduced diameter.
The pipette of any one of Claims 8 to 11, further including a smoothly rounded rim (100) at said opening, said smoothly rounded rim being integral with said distal-most surface of said tip and integral with a surface of said lumen within said pipette.
The pipette of Claim 8, wherein said semen straw retaining means comprises a portion (90) of said lumen wherein said lumen has a reduced diameter.
The pipette of Claim 13, wherein said reduced diameter portion (90) of said lumen is at said distal end of said lumen.
The pipette of Claim 11 or 13, wherein said reduced diameter portion (90) of said lumen is tapered toward said distal end of said lumen.
The pipette of Claim 15, wherein said tapered reduced diameter portion (90) of said lumen is dimensioned such that a distal end of a semen straw driven in a proximal to distal direction through said lumen will lodge securely in said tapered reduced diameter portion (90).
The pipette of Claim 16, wherein said lumen's diameter at the proximal-most extend of said tapered reduced diameter portion (90) is larger than a semen straw, and wherein the distal-most extend of said tapered reduced diameter portion (90) has a diameter smaller than the diameter of a semen straw.
The pipette of any one of Claims 8 to 11, wherein said semen straw retaining means comprises a first reduced diameter portion (88) of said lumen, said first reduced diameter portion (88) being cylindrical, and wherein said semen straw retaining means further comprises a second reduced diameter portion (90), said second reduced diameter portion (90) being more proximal than said first portion and tapered toward said first reduced diameter portion.
The pipette of Claim 18, wherein said second reduced diameter portion is directly adjacent to said first reduced diameter portion.