Sperm/Andrology Lab: Intracytoplasmic Sperm Injection

Intracytoplasmic Sperm Injection (ICSI) is a form of gamete (sperm and egg) micromanipulation that involves the direct injection of a single sperm into the cytoplasm (inside portion) of an oocyte.

ICSI is used for several reasons:

• Previous in vitro fertilization (IVF) cycles with poor fertilization results. While it is true that ICSI may have a lower fertilization rate than doing IVF, when someone has poor fertilization in a previous cycle the ICSI procedure can improve the chances of fertilization.
  
  If normal fertilization will occur through standard IVF then ICSI will not be useful. ICSI adds an additional cost to the cost of an IVF cycle.
• Poor semen parameters. If the semen analysis and semen profile indicate there is a significant enough problem for fertilization to occur you may be advised to choose ICSI. Generally a swim up total motile count of less than 100,000 indicates a significant problem for potential fertilization. ICSI is not indicated when the swim up counts are greater than one million.
  
  For counts falling between these numbers some couples will choose ICSI to avoid potential problems with fertilization even though the risk is not as significant as those patients with total motile counts less than 100,000 (less than 0.1 mil/ml).
• Azospermia. Male patients that do not produce sperm may have to undergo procedures involving aspiration of sperm from the epididymis of the testicle.
  
  Some men have a congenital absence of the duct that transports sperm, known as the vas deferens. Others may have acquired obstructions of the genital tract from things such as scar tissue, infections, and vasectomies. Other causes for azoospermia include deficiencies in sperm production that may be due to physical or hormonal defects.

The Procedure

By using a powerful microscope we are able to isolate a single sperm, aspirate it into an extremely thin glass pipette and inject it into a single egg.

In the image below, the pipette on the left is used to hold the oocyte in position while the glass pipette on the right is injecting a sperm into the cytoplasm. Prior to the injection of the sperm, granulosa cells were cleared off from around the oocyte.

Sperm Collection and Storage

Sperm cryopreservation is offered as a way to provide storage of sperm that may be difficult to obtain in the case of testicular aspiration.

Cryopreservation also provides a means of a back up specimen when low sperm counts are involved.

Risks

ICSI has been studied to determine if there are risks associated with the procedure. Information is relatively limited. Here is an excerpt from the ICSI consent form:

“I acknowledge that due to the newness of this procedure not all of the risks are known. The micromanipulation procedure carries the following known risks:

1. Damage to the oocyte: During the micromanipulation procedure, there is an increased risk that the oocyte may be damaged or undergo degeneration due to the injection procedure. Up to 20 percent of oocytes that are subjected to ICSI may not survive the injection and will degenerate.
2. Birth defects: There is no evidence that the micromanipulation procedure itself has resulted in an increase in birth defects over the general population, however, this is a new technique and the information on birth defects could be incomplete.
   
   Sperm production is coded genetically on the Y chromosome and if there is genetic component to the male factor infertility this may be passed on to any male offspring resulting from this process. Men with severe oligospermia are encouraged to seek genetic counseling and karyotyping due to the increased risk of this condition.
   
   With any reproductive technology procedure, women who conceive are encouraged to consider genetic evaluation of the fetus through chorionic villus sampling or amniocentesis.
3. Polyspermic fertilization: Due to the micromanipulation procedure there is a risk that polyspermic fertilization (fertilization of an oocyte by more than one sperm) may occur. Oocytes exhibiting polyspermic fertilization will not be used for embryo transfer or cryopreservation.”

The American Society for Reproductive Medicine has a fact sheet (PDF, 10KB) available.

Assisted Hatching

Assisted hatching is another micromanipulation technique that involves the removal of a small portion of the zona pellucida (outer layer of the oocyte or early embryo). This process is done prior to transfer by applying tiny amounts of enzymatic solution with the aid of the micromanipulation microscope.

The process is thought to improve the hatching, or escape, of the blastocyst from the zona pellucida. Age is the predominant determining factor for using assisted hatching. Assisted hatching is not used very frequently and is considered on an individual basis.