For sperm to fertilize an egg, the sperm's head must attach to the outside of the egg. It then must break through to the inside, where fertilization takes place. If the egg's outer layer has become hardened or thickened, or if the sperm is abnormal and cannot swim effectively, it will be difficult for the sperm to penetrate it.
Standard IVF vs. ICSI
In an IVF procedure, an egg is fertilized in a laboratory dish. Healthy sperm collected from the patient's partner or a selected donor is added to the dish to surround the egg. The sperm will naturally fertilize the egg by attaching itself to its outer membrane and breaking through into the egg. The fertilized egg (embryo) is transplanted into the uterus when it reaches a certain stage of development approximately five to six days after fertilization. If it implants into the lining of the uterus successfully, a pregnancy results.
There are times, however, when surrounding the egg with sperm in the dish may not result in fertilization. Based on the circumstances or results of a prior semen analysis, doctors may opt for ICSI to help improve fertilization success. This procedure can frequently solve the issue of male factor infertility or poor fertilization in IVF cycles. ICSI is essentially an extension of IVF that works to control some of the variables that affect fertilization and increases the chances of an embryo resulting in pregnancy.
How Is ICSI Performed?
ICSI is performed in conjunction with in vitro fertilization (IVF). Patients will undergo egg retrieval, and the egg will be injected with a single sperm in the lab through the process of ICSI with the hope of growing into a healthy embryo to be transferred to the carrying uterus.
Steps for Egg Retrieval
To prepare for egg retrieval, patients administer hormonal injections to stimulate the ovaries to produce multiple eggs for an average of 10 days, followed by an injection of human chorionic gonadotropin (hCG) or leuprolide acetate to assist in the eggs' final maturation.
When the eggs are ready for actual retrieval, a transvaginal ultrasound guides a thin needle through the vaginal wall into the ovary, then suction draws out and collects the eggs. This is performed under anesthesia and is a relatively short procedure lasting 10-20 minutes.
Unless frozen sperm is used, it is collected on the same day that egg retrieval occurs. The person supplying the sperm must collect ejaculate into a lab-provided container and deliver it to the lab within 30 minutes. The semen is analyzed for volume, mobility, and quality.
The ICSI Procedure
The ICSI procedure is performed with these steps:
1. The embryologist holds the mature egg in a lab dish using a small glass tube equipped with a suction bulb.
2. Using a thin needle, a single sperm is immobilized and picked up.
3. The needle is inserted into the egg.
4. The sperm is injected directly into the egg.
5. The needle is withdrawn.
Now the waiting begins.
After the ICSI Procedure
Following the completion of the procedure, the embryology team monitors the embryos' progress to look for signs of successful fertilization. Cell division should begin within one day if the fertilized embryo is healthy. In many cases, the embryos are grown for five to six days, and at this point, if the patient elects to have preimplantation genetic testing performed (PGT) this is when the surviving embryos are biopsied (cells removed and sent for additional testing) and then frozen.
If a fresh embryo transfer is performed, the developing embryo will need to grow appropriately for at least three to six days. When it is ready to transfer, a long, thin tube (catheter) is inserted through the vagina into the uterus under ultrasound guidance to inject the embryo into the uterus. The embryo must implant in the uterine lining for pregnancy to occur. If PGT testing is being performed, a frozen embryo transfer will be performed at a later date.
Who May Benefit from ICSI?
Male factor infertility is one of the causative factors in over one-third of male infertility cases. It usually results from complications in the sperm's production or delivery. In such a case, ICSI would be high on the list of options to overcome infertility. A man who has undergone a vasectomy reversal would also be a candidate for this procedure, even if the sperm is healthy otherwise. Other examples of infertility that may be helped through the ICSI procedure include:
• Low sperm count. The male partner doesn't produce enough sperm for a successful attempt using artificial insemination or IVF.
• Infertility that cannot be explained.
• The semen lacks sperm because of a blockage in the reproductive tract of the male.
• The sperm is unable to attach to an egg.
• Traditional IVF has been unsuccessful, even with fit sperm.
• The eggs used were matured in vitro.
• The eggs were frozen before use.
Even when it isn't specifically indicated, some physicians may choose to use ICSI when appropriate.
What Are the Risks of ICSI?
Compared to conventional IVF, some studies of the ICSI procedure suggest a possible connection between ICSI and an increased risk for intellectual delays, autism, chromosomal abnormalities, and birth defects such as Beckwith-Wiedemann syndrome, hypospadias, Angelman syndrome, and sex chromosome abnormalities. These are rare, occurring in less than 1% of babies conceived through ICSI with IVF. Other possible risks include:
• Ovarian hyperstimulation syndrome in response to excessive fertility drugs
• Multiple births, either twins or triplets
• Increased risk of premature labor and low birth weight
• Slight increase in risk compared with IVF
• The need for a cesarean section for delivery is slightly increased
On average, fertilization occurs through ICSI in 70% to 85% of cases. The rate of live births reflects the number of healthy children born following an IVF/ICSI cycle. These success rates are classified based on maternal age and will often vary due to additional factors affecting the eggs and sperm.
Take the First Step
If you'd like to learn more about IVF, ICSI, or other fertility treatments that may be a solution for you, contact the infertility specialists at Advanced Fertility Care to set up a consultation.