Tree of Life Center / Microsort Gender Selection Technology

Microsort Gender Selection Technology

Tree of Life Center is a Microsort sperm sorting clinic. In connection with our Tree of Life Center Mexico, we can offer Sperm Microsorting to patients worldwide. Microsort is the only method for intrauterine insemination IUI gender selection. Many clinics provide sperm spinning by weight, also known as Erickson's method, but that method can not compare to the micro sorting technology. While this technology is not mainstream and not suited for every patient, there are particular cases where sperm micro sorting might offer the solution for family balancing. Very few places in the world maintain access to this technology, and we are happy to include it in the repertoire of our services. For the more commonly used gender selection via IVF, please see our IVF/ICSI page.

What is Microsort?

  • MicroSort® is a scientifically proven preconception process that increases the probability of having a baby of the desired gender by separating male and female sperm. It is currently the only proven method to perform sex selection by controlling what sperm fertilizes the egg.

  • Semen samples usually contain 50% of spermatozoa carrying the Y chromosome that will produce a boy and 50% of spermatozoa carrying the X chromosome that will create a girl.

  • The MicroSort® gender selection process separates spermatozoa, the ones that will result in a girl or the ones that will result in a boy, from the rest of the sample, allowing a couple to use a sample that only contains the spermatozoa that were selected according to the criteria we choose: for a healthy boy or a healthy girl.


Where was Microsort invented?

MicroSort® Laboratories are a branch of the Genetics & IVF Institute. The Genetics & IVF Institute is a fully integrated, comprehensive fertility center located in Fairfax, Virginia, USA. Since 1984, the Institute has been an innovator in infertility treatment and genetics care and has helped thousands of patients worldwide realize their dreams of starting a family. Tree of Life Center cooperates with Genetics & IVF Institute to provide Microsort Technology to anyone in need of it.


What is the MicroSort® technology based on?

MicroSort® is a method based on the difference in the amount of genetic material in the sperm, where the X chromosome has approximately 2.8% more DNA material than the Y chromosome.


How does MicroSort® separate the sperm?

·       During the MicroSort® sorting technique, the sperm sample is washed to remove seminal liquid along with not moving (nonmotile) sperm. Afterward, the sample is stained with a distinctive fluorescent stain that attaches temporarily to the DNA contained in the spermatozoa.

·       The stained spermatozoa are analyzed one by one by a flow cytometer, where cells go through a laser that makes the stain attached to the DNA fluoresce. The spermatozoa containing the X chromosome (which has more DNA and, therefore, more stain) will have a more energetic shine than the spermatozoa containing the Y chromosome.

·       The flow cytometer uses special software to identify sperm, which exhibits the fluorescence signature of cells that match the healthy sperm of the desired gender. Those sperm will be separated from the rest of the sample, obtaining an enriched sperm sample ready for use.


How long does it take to sort the sample?

The sorting process of each semen sample takes between 7 and 9 hours; it can be divided into two parts:

•    The first part of the process takes about 3 hours, including the necessary tests for the initial sample, washing, and staining.

•    The second part and actual sorting time depends on the number of cells recovered and the quality of the sample, and it could go from 4 to 6 hours.

· Cryopreserved samples require an additional hour for processing.


How can the sorted sperm cells be used?

· MicroSort® Laboratories perform the sorting procedure and generate an enriched sperm sample that can be used with a wide variety of assisted reproductive techniques, such as intrauterine insemination (IUI), in vitro fertilization (IVF), Intracytoplasmic sperm injection (ICSI), Preimplantation genetic diagnosis/screening (PGD/PGS), among other procedures. Gynecologists and specialized reproductive endocrinology physicians perform these techniques.

· Only MicroSort® Laboratories have the technology to perform this sperm sorting procedure and are designed to offer this technology and work in collaboration with clinics and physicians around the globe that perform these assisted reproduction techniques.

· The different options of assisted reproductive techniques depend on the case of each couple that, along with their physician, can define the assisted reproduction technique to be used, monitor the ovulation cycle, and define the optimal date for the MicroSort® procedure.


Can multiple pregnancies be achieved with MicroSorted sperm cells?

There are two types of multiple pregnancies:

•    The ones that occur when an embryo divides itself and identical twins are created. This type of multiple pregnancies depends on heritage and cannot be obtained through technologies of assisted reproduction.

•    The ones that occur when two or more embryos are implanted, generating fraternal twins. This type of multiple pregnancies can be achieved through technologies of assisted reproduction.

·       MicroSort® lab generates a sample with enough sorted sperm cells to fertilize any available eggs; therefore, it can be used in search of multiple pregnancies.


What tests are required and performed before scheduling the sort?

Two different tests have to be done at least a few days before the day of the procedure.

·       MicroSort® lab will need these tests to be able to confirm that you are a candidate for the procedure or, if required, offer different options and estimate results according to your case.

·       Semen Analysis: Semen analysis must be done in advance to determine if the specimen will have enough sperm cells for a sort. Semen analysis is done after 72-hours of ejaculatory abstinence, at any semen-testing lab to determine the number of cells, motility, and progression.

·       Blood Test: including HIV 1/0/2 (Ag/Ab; 4th Generation), HTLV-I/II Antibody, Qualitative, Hepatitis B Surface Antigen, Hepatitis B Core Total Ab, Hepatitis C Virus, Cytomegalovirus CMV Total Antibody, Syphilis (T pallidum, RPR), and Chlamydia/Gonococcus Nucleic Amplification. Currently, the lab does not handle samples with positive results for any of the mentioned tests.


What is the minimum amount of cells needed for MicroSort®?

·       With IUI, the minimum amount of cells is 100 million Total Motile Cells (TMC), and for IVF or ICSI, the minimum amount is 70 million TMC. These values refer to the total amount of cells in the sample, regardless of the volume; in the case of frozen samples, the amounts are post-thaw.

·       For IVF with or without ICSI, the number of cells can be achieved by freezing more than one ejaculate.

·       If there are any previous semen analyses, you can forward them to Tree of Life Center and our staff will inform you if the amount of cells is above the minimum or the different options you have to consider.


How many sperm cells are sorted from each procedure?

·       MicroSort® targets to recover as many cells as possible; the average recovery is between 300 and 500 thousand cells with average motility after the sort is 75%. This number changes according to the initial quality of the sample. With the minimum amount of cells mentioned before, the result should be within this range.

·       In the case of IVF or ICSI, only a few cells are required per cycle. Therefore the amount of cells is divided into parts of approximately one hundred thousand cells. Depending on where the treatment is being performed, the total sample is cryopreserved in multiple vials for future use, or one of the parts is delivered fresh at a local clinic for its use on the same day.

·       For IUI, the only recommended use is fresh, so the sorted sample is delivered to the local clinic or physician for its use. This can prove logistically impossible since the sorting is performed outside of the United States. Therefore at present, Tree of Life Center Los Angeles utilizes MicroSort® in conjunction with IVF/ only. Fresh inseminations with microsorted sperm are only possible at the Tree of Life Center Mexico in Guadalajara.

·       MicroSort® has proven that with proper timing of ovulation, using this low number of sperm cells, pregnancy can be achieved in a similar percentage to those where millions of cells were used for insemination.


Can a sample be cryopreserved and shipped?

·       Yes, samples can be cryopreserved and shipped to MicroSort® labs for sorting and/or shipped from the MicroSort® labs once they are sorted and cryopreserved (Recommended just for IVF with  ICSI cycles).

·       Cryopreservation and thawing do reduce the number of viable sperm cells available for sorting, and it is recommended to cryopreserve multiple ejaculates to give a total of at least 200 million TMC. In some cases, the patient may choose to travel to MicroSort® lab to produce a fresh specimen instead of cryopreserving multiple ejaculates.

·       Depending on the quality of the initial sample, the sorted sample is cryopreserved multiple vials, when possible, according to the previous arrangement made with the clinic or physician collaborating with MicroSort® lab.


Can a cryopreserved sample be used for IUI?

During the cryopreservation and thawing process, an average of 50 to 60% of cells will not survive, and there can be a lower progression post-thaw; only IVF with/without ICSI procedures are recommended for the use of cryopreserved sperm.


Can donor sperm be used for MicroSort® procedures?

·       Yes, donor sperm may be used for any treatment along with MicroSort®.

·       Because of the high quality of donor sperm and the high freezing and thawing proven capacity of the cells, the donor sperm may be used for IUI.


How can you tell if MicroSort® is effective at sorting sperm?

There are two ways of determining how MicroSort® is effective at increasing the percentages of desired sperm cells.

1. Measuring the percentage of X and Y bearing sperm in a small unused portion of the sorted sample. A DNA analysis method called FISH (Fluorescence In Situ Hybridization) uses DNA probes that specifically attach to either the X or Y chromosome in sperm. X bearing sperm emits a red/pink color, and Y-bearing sperm emits a green color. The cells can be identified and counted under a microscope to obtain a percentage of purity. Currently, MicroSort® offers an average purity of 91% X sort and 80% for Y sort.

2. Determining the percentage of the children of the desired gender that have been born using MicroSort®. The success rate is 93% for females (X sorts) and 82% for boys (Y sorts).

3. MicroSort® cannot guarantee a child of the desired gender. What this technology does is to increase the percentage of sperm cells of the desired gender.


What is the pregnancy rate for MicroSort®?

The pregnancy rate depends on a number of factors, among them the age of the woman and the quality of semen. On average, the pregnancy rate is similar to the treatment rates without MicroSort®. Your physician will be better qualified to give you a rate according to the treatment and your clinical case. Many patients become pregnant on the first attempt, but on average, it takes two to three attempts to achieve pregnancy with IUI.


What are the fertilization and cleavage rates for MicroSort®?

The information was collected from different collaborating fertility clinics where the IVF or ICSI procedures were performed.

· Fertilization Rate 71.4%

· Cleavage rate of 91.6%


How many babies have been born using MicroSort® procedure?

MicroSort® was first offered to couples in 1994, and there have been more than 1400 babies born.


Can MicroSort® help to prevent malformation?

According to the statistics, MicroSort® can. The general population has a 4% malformation rate; couples using MicroSort® reduce this rate to 2.8%. By sorting for gender, certain gender-linked genetic diseases can be reduced.


What has the FDA mentioned regarding MicroSort® procedure?

Genetics & IVF Institute has the only license to perform the sorting procedure of sperm cells in humans called MicroSort®. A clinical trial to search for FDA approval was started and discontinued due to economic reasons, because of this, MicroSort® is no longer performed in the US. It is worth mentioning that the FDA recognizes that MicroSort® procedure is SAFE and EFFECTIVE, but discontinued the use of the method for family balance at not finding "public health benefits" for it.


Indications for MicroSort®


· Negative results for STD from HIV 1/0/2 (Ag/Ab; 4th Generation), HTLV-I/II Antibody, Qualitative, Hepatitis B Surface Antigen, Hepatitis B Core Total Ab, Hepatitis C Virus, Cytomegalovirus CMV Total Antibody, Syphilis (Treponema Pallidum, RPR), and Chlamydia/Gonococcus Nucleic Amplification. Should be recent (no more than six months old to the day of the procedure), some cases could require that the test are done on-site a couple of days before the procedure. MicroSort®, the lab is not able to process infectious samples.

· Semen analysis to verify the quality of the sample is above the minimum required. Should be recent (no more than six months old to the day of the procedure). The requirements change according to the method to perform, and different options could be offered depending on the case.

· Cryopreserved samples that are shipped for MicroSort® should NOT be washed. If the case allows for the sample to be shipped cryopreserved, the samples should not be washed or processed in any way prior to being cryopreserved since the sorting procedure requires the samples to be washed and processed before the staining is done. Multiple samples will be necessary, and the number of samples will depend on the quality of the samples and details of the case. Please contact MicroSort® staff for further information regarding these options.



· Shipment of cryopreserved samples requires a particular tank or container to be transported.

· Shipment to other countries implies an export and import process that could require additional documentation and time.