Abstract:
A method of embryo transfer (“ET”) that improves fertility rates by eliminating transferred air during the procedure is provided. Also provided is a method for hormonally enhancing the uterine wall of a patient either prior to or during the time of ET. Quantitative administration of transfer solutions is accomplished with a modified apparatus that provides for implantation of an embryo into the uterus of a patient. The apparatus comprises an outer sheath and an inner lumen arranged to be slidably disposed within the outer sheath. The inner lumen includes at least one visual marker situated on the exterior surface adjacent its distal end thereof.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/188,021, filed on Aug. 6, 2008. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a minimally-invasive medical procedure of embryo transfer utilizing a uterine transfer catheter that deposits fertilized eggs into the uterus whereby implantation of an embryo occurs. 
     BACKGROUND OF THE INVENTION 
     Human in vitro fertilization (IVF) and embryo transfer (ET) was first successfully performed in 1978 and has since been widely practiced to treat infertile couples who have failed with other conventional methods. The IVF/ET procedure typically involves hormonal stimulation of the female to initially suppress her natural ovulation, and then stimulate development of ovarian follicles with fertility drugs. The mature eggs are harvested from the ovary using a needle and then sorted by maturity and egg quality. Preferred eggs are then mixed with sperm from the male to be fertilized. After some time, the embryo(s) mature and are transferred, along with a volume of fluid, to the uterus using a delivery catheter. The delivery catheter is made of soft plastic material to avoid damage to the endometrium of the uterus. The delivery catheter is guided through the cervix to the uterus by a physician where the loaded embryos within the fluid is deposited, completing the ET. 
     One method of catheter loading is referred to as “the transfer bubble method” and has been universally accepted by professionals and has been in place over four decades. The catheter is loaded with a series of alternate air and transfer liquid (e.g., saline, P-1 or glycerine) in volumes approximating 3 microliters. Volumes of air separate the transfer liquid to keep the embryos contained within the fluid and also to ease visualization of the components. Upon ejection of the fluids, about 100 microliters of air is also ejected with the quantity of medium and transfer liquid containing the embryos. Generally, there are a total of approximately 6 microliters of fluid and 100 microliters of air deposited at the ejection site in the uterus. These volumes can vary greatly depending on specific hospital protocol and there has been research done to study the effects of varying medium volumes upon pregnancy rates. Some studies demonstrate that a transferred volume of less than 50 microliters is optimal for successful ET whereby other studies show that widely varying transfer volumes of medium have little effect on the outcome of IVF procedures. 
     Studies also have found that the transferred air within the uterus can sometimes act as a barrier that prohibits movement of the embryos from the site of ejection to the optimal location for implantation within the uterus. This air bubble creates an area of surface tension to which the embryos may adhere and remain positioned, prohibiting interaction of the embryo with the receptive surface of the uterus. Moreover, under the transfer bubble method, latent embryos can attach themselves to the internal walls of the catheter requiring further manipulation of the embryos and thereby decreasing the likelihood of successful ET. 
     While improvements in the techniques and instrumentation used in this procedure have provided significant increases in pregnancy rates and births, the overall numbers remain fairly low, around 25%. There are several factors that impact on IVF success including the design of the delivery catheter. Ultrasound guided catheters have been included in ET procedures to aid visualization of the tip and facilitate optimized embryo deposition at the prime location within the uterus. 
     In addition, the high cost of the IVF procedure combined with this low probability of success compels couples to deliver multiple embryos to increase the chance of at least one successful implantation. Often, unwanted multiple births result and jeopardize the health of mother and/or children, which has recently raised questions concerning the medical ethics of such practice. If a higher pregnancy rate could be achieved, the need for multiple embryo delivery would be lessened or possibly eliminated. 
     With the high cost of IVF and contrastingly low pregnancy rate, what is needed is a method of ET that reduces the quantity of air that is typically transferred to the uterus along with the embryos in medium. The conventional method of catheter loading referred to as “the transfer bubble method” that deposits these relatively large volumes of air has been taught worldwide and universally accepted by professionals in the IVF field. Even as studies demonstrate the difficulties associated with this large transferred air bubble, this method is the only one used. An improved method of ET that eliminates any volume of transferred air will undoubtedly improve the probability of successful embryo implantation and increase pregnancy rates overall. 
     SUMMARY OF THE INVENTION 
     A method of embryo transfer (“ET”) that improves fertility rates by eliminating transferred air during the procedure is provided. Also provided is a method for hormonally enhancing the uterine wall of a patient at the time of ET. 
     Direct administration of hormones into the uterus may be achieved by including the hormones in the milieu of solutions utilized during the transfer of one or more embryos into the endometrium during ET. Luteal support is maintained by slow dissolution of the deposited hormones by direct injection into the uterus, as opposed to introducing the hormones systemically. 
     Quantitative administration of the hormonal solutions is accomplished by a modified delivery catheter that comprises an outer sheath having a proximal end and a distal end. An inner lumen is arranged to be slidably disposed within the outer sheath. The inner lumen includes a proximal end, a distal end, and a passageway therethrough. The inner lumen includes at least one visual marker situated on the exterior surface adjacent its distal end thereof to enable accurate volumes of fluid media in which one or more embryos are situated to be drawn into the deliver catheter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of an embodiment of the delivery catheter of the present invention with a syringe shown attached at the proximal end thereof, the syringe including a barrel and a plunger disposed therein; 
         FIG. 2  is a cross-sectional view taken along line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of a portion of an embodiment of the delivery catheter of the present invention wherein the inner lumen is illustrated as retaining therein a first portion comprised of a wash fluid, a second portion comprised of an oil, and a third portion comprised of one or more embryos disposed within a fluid culture medium; 
         FIG. 5  is an elevational view of the delivery catheter of the present invention showing the inner lumen slidably disposed within the outer sheath; 
         FIG. 6  is an front end view of the delivery catheter of the present invention; and, 
         FIG. 7  is an illustration of several embryos implanted on the wall of a uterus after an embryo transfer procedure has been conducted. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The problems associated with large quantities of transferred air during ET procedures are solved and a technical advance is achieved in an improved delivery catheter for use in an ET procedure and method for loading the delivery catheter that involves replacing the air bubble with a liquid medium, e.g., a separation oil, at the start of the procedure, to improve the rate of fertility. 
     Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown at  6  in  FIGS. 1 through 6 , an embodiment of the delivery catheter is illustrated as including an outer sheath  10  being in the form of a hollow tube and provided towards its proximal end with a hub  20  provided with a series of axially extending fins  24  to assist in manipulation. As best shown in  FIG. 5 , the distal end of the outer sheath  10  is provided at intervals of a predetermined distance, e.g., one centimeter, with gradations  28  of any suitable measure, e.g., microliters. The gradations are marked as a plurality of rings about the distal end, and which may be slightly indented into the outer surface thereof. Alternatively, the gradations  28  may be of a distinctive color. As best seen in  FIGS. 5 and 6 , the remote distal tip  32  of the outer sheath  10  is chamfered for minimal trauma. The outer sheath  10  is formed of any suitable material, and preferably a generally rigid plastic material such as TEFLON®. 
     The outer sheath  10  is adapted to accommodate therewithin an inner lumen  36  having an external diameter such as to be an easy sliding fit within the outer sheath  10  and an internal passageway  34  having a diameter of a size to readily accommodate an embryo. As best shown in  FIGS. 1 and 5 , the inner lumen  36  is provided at its proximal end with a hub  40 , the hub  40  being provided about its external surface with a plurality of axially extending fins  44  to assist manipulation. The inner lumen  36  is provided with an inner bore  42  ( FIG. 2 ) that is in open communication with the internal passageway  34 . The hubs  20  and  40  are adapted such that they interlock in their closed position as shown in  FIGS. 1 and 5 . The hubs  20  and  40  are provided to enable a physician and/or an embryologist to hold the outer sheath  10  with one hand while using the other hand to slide the inner lumen  36  through the outer sheath  10  during an embryo transfer procedure. 
     Referring now to  FIGS. 1 and 5 , the distal end of the inner lumen  36  is provided at intervals of a predetermined distance, e.g., one centimeter, with gradations  38  of any suitable measure, e.g., microliters. The gradations  38  are marked as a plurality of rings about the distal end, and may be slightly indented into the outer surface thereof. Alternatively, the gradations  38  may be of a distinctive color to allow the operator to precisely aspirate an exact quantity of a fluid medium to achieve a consistent protocol. As best shown in  FIGS. 2-5 , the remote distal tip  46  of the inner lumen  36  is provided with a smoothly radiused chamfer for minimal trauma to the uterine tissues. The inner lumen  36  in accordance with this embodiment of the invention is preferably soft and flexible and formed of a biologically acceptable synthetic polymer. 
     Referring now to  FIGS. 1-4 , there is shown a standard syringe  52  having a barrel  56  and a plunger  60  disposed therein. Referring now to  FIG. 1 , the syringe  52  is shown with the plunger  60  disposed fully within the length of the barrel  56 . The syringe  52  includes a distal end  61  which is sized to snugly fit within the inner bore  42  of the inner lumen  36 . 
     Referring now to  FIGS. 2-4 , to load the inner lumen  36  for the embryo transfer procedure, the distal end  61  of the syringe  52  is inserted into the inner bore  42  of the inner lumen  36  with the plunger  60  disposed fully within the length of the barrel  56  of the syringe  52 . A predetermined amount of a first fluid medium, e.g., from 6 to 9 microliters of a wash fluid  64 , is drawn into the internal passageway  34  of the inner lumen  36  and into the barrel  56  of the syringe  52  by withdrawing the plunger  60  along a portion of the length of the barrel  56 . Next, an excess amount of the wash fluid  64  is ejected from the syringe  52  and internal passageway  34  by depressing the plunger  60 . By utilizing the gradations  38  marked on the distal end of the inner lumen  36 , an accurate volume of wash fluid  64  can be obtained within the internal passageway  34 . The ET delivery catheter  6  is then held vertically to enable air to escape out the remote distal tip  46  of the inner lumen  36 . Often, the sides of the ET delivery catheter  6  are tapped by the forefingers to loosen any air bubbles from the internal sides of the barrel  56 . 
     Referring now to  FIG. 3 , a predetermined amount of a second fluid medium, e.g., approximately 3 microliters of a separation oil  68 , may be drawn into the internal passageway  34  of the inner lumen  36  adjacent the first fluid medium, by slowly withdrawing the plunger  60  from the barrel  56  of the syringe  52 , as indicated by the arrow in  FIG. 3 . Any suitable separation oil  68  may be utilized for the purpose of separating the wash fluid  64  from the culture medium containing one or more embryos  72 . One particular product which could be utilized as a separation oil in accordance with the present invention is an enhanced oil for tissue culture manufactured by Conception Technologies of San Diego, Calif. under catalog numbers OTC-100 (100 mL) and OTC-500 (500 mL). By utilizing the gradations  38  marked on the distal end of the inner lumen  36 , an accurate volume of the separation oil  68  within the internal passageway  34  can be achieved. Likewise, unwanted air and any unneeded volume of separation oil  68  can be expelled through the remote distal tip  46  by depressing the plunger  60  of the syringe  52  and/or tapping with forefingers to loosen air bubbles. 
     Lastly, as best shown in  FIG. 4 , the gradations  38  located at the distal end of the inner lumen  36  enable an operator to draw a predetermined amount of a third fluid medium, e.g., approximately 3-6 microliters of a fluid culture medium containing one or more embryos  72 , into the internal passageway  34  of the inner lumen  36 . As shown in  FIG. 4 , the third fluid medium in which the embryos  72  are located is shown as being situated adjacent the separation oil  68 . The fluid culture medium in which the embryos  72  are located includes a water-based portion and sometimes, an oil-based portion. When an oil-based portion is used, it is done so to prevent evaporation of the water-based portion and prevent dehydration of the embryos  72 . One product which is suitable for utilizing as the oil-based portion of the fluid culture medium is the enhanced oil for tissue culture manufactured by Conception Technologies of San Diego, Calif. under catalog numbers OTC-100 (100 mL) and OTC-500 (500 mL), as mentioned in connection with the separation oil described above. 
     As best shown in  FIG. 4 , the three fluid media, e.g., the wash fluid  64 , the separation oil  68 , and the plurality of embryos  72  disposed within a fluid culture medium are shown disposed within the internal passageway  34  of the inner lumen  36 . The separation oil  68  is utilized as a replacement to the volume of air which under existing techniques is utilized to separate the wash fluid  64  from the embryos  72 . By replacing the volume of air with the separation oil  68 , the drawbacks associated with the use of air in embryo transfer procedures is eliminated. For example, the use of a separation oil  68  will facilitate movement of the embryos  72  from the site of ejection to the optimal location for implantation within the uterus and will facilitate interaction between the embryo  72  and the receptive surface of the uterus. Embryos  72  will flow more readily within a liquid environment than a gaseous (air) environment. 
     In accordance with the present invention, ingredients may be added to the separation oil  68  and/or wash fluid  64 , including progesterone and/or estrogen to stimulate the luteal phase which determines the time of ovulation within the menstrual cycle and establishes the peak moment of receptivity within the uterus. By including such hormones within the separation oil  68  and wash fluid  64  for administration into the uterus, the concentrations of such hormones needed for luteal stimulation and support is substantially less than required when such hormones are administered by vaginal suppository, intramuscular or other systemic means. 
     It should be understood that the hormones needed for stimulation of the luteal phase may be added to the separation oil  68  and/or the wash fluid  64  and delivered directly into the uterus during an ET procedure utilizing the delivery catheter  6  described herein. Alternatively, the hormones may be introduced directly into the uterus utilizing any other suitable delivery device and may be delivered into the uterus at any point in time, either prior to or during the ET procedure. 
     Referring now to  FIG. 5 , once the predetermined volumes of fluid media have been accurately drawn within the internal passageway  34  of the inner lumen  36 , delivery of the embryos  72  to the uterus  76  is possible. The distal ends of the outer sheath  10  and inner lumen  36  are brought together. The physician and/or embryologist directs the end of the ET delivery catheter  6  transvaginally to the desired location within the uterus, either by conventional means or by improved ultrasound guided techniques. The gradations  28  provided at the distal end of the outer sheath  10  enable the physician and/or the embryologist to determine the distance the catheter  6  has been inserted into the uterus. The ET delivery catheter  6  must be gently advanced through the cervical canal to overcome obstruction or tortuous route so that the delivery catheter  6  can pass into the uterus. 
     The physician and/or embryologist then ejects the embryos  72  through the distal end of the inner lumen  36  by depressing the plunger  60  of the syringe  52 . In this manner, the entire contents are expelled out of the internal passageway  34 . In this manner, the wash fluid  64  washes the wall of the internal passageway  34  and carries out any adherent embryos  72  that may have attached themselves to the wall of the internal passageway  34  by way of surface tension. Once the embryo transfer is completed, the physician extracts the distal tip of the ET delivery catheter from the cervix. This method of ET is superior to other methods because the delivered embryos are much more likely to flow within a liquid environment than a gaseous (air) environment. 
     The details of the construction or composition of the various elements of the ET delivery catheter  6  of the present invention not otherwise disclosed are not believed to be critical to the achievement of the advantages of the present invention, so long as the elements possess the strength or flexibility or softness needed for them to perform as disclosed. The details of such construction is believed to be well within the ability of one of ordinary skill in this area, in view of the present disclosure, and are within the spirit of the invention and the scope of the claims.