Micromanipulation of Oocytes using
Intracytoplasmic Sperm Injection (ICSI)

The advent of intracytoplasmic sperm injection (ICSI) has revolutionized the treatment of moderate to severe male factor infertility. Men previously considered untreatable with conditions such as congenital bilateral absence of the vas deferens (tubes that carry the sperm) or very low sperm counts are now successfully fathering children with ICSI. Although the technique does not correct the condition leading to low counts or severely abnormal morphology it can successfully bypass these previously “non-fertile” cases of infertility.

In conventional in vitro fertilization the oocytes are combined with approximately 100,000 sperm/oocyte in order to achieve fertilization. The sperm must be of sufficient quality with sufficient motility and have normal shapes in order to penetrate the oocyte. Prior to ICSI’s introduction in 1992, the results of in vitro fertilization in cases of severe male factor were disappointing.

In the case of ICSI, the oocyte is held in place with micromanipulation tools and injected with a single sperm. The technique differs from in vitro fertilization by overcoming the barriers that can prevent sperm from entering the oocyte. It does not insure fertilization; however, it insures that the sperm has entered the oocyte.

Indications for ICSI:

• After previous failed attempts at IVF Failure or reduced fertilization in a previous IVF attempt is an indication for ICSI. Successful ongoing ICSI pregnancies have been reported in large series of patients who have failed previous IVF.
• Teratospermia- “Poor sperm shapes” ICSI is now the treatment of choice with severe teratospermia, <4% normal forms using Kruger strict morphology. Individual sperm are selected for the best morphology with ICSI, and may help to bypass any hindrances to fertilization that poor morphology causes.
• Immunological Infertility- When high quantities of antisperm antibodies are present in the male, treatment with corticosteroid therapy, sperm washing, and routine IVF has been less than acceptable. ICSI is now the recommended treatment for those patients with this condition.
• Severe Oligoasthenospermia and Testicular Failure- The best results with ICSI fertilization rates are reported using ejaculated sperm, even in the presence of severe defects in sperm density, motility, and/or morphology. While good results are now observed using testicular and epididymal sperm, ejaculated sperm should be used when this option exists. In testicular failure with no sperm in the ejaculate, testicular sperm extraction (TESE)combined with ICSI has resulted in successful ongoing pregnancies.
• Obstructive Azoospermia- Congenital Absence of the Vas Deferens, Failed Vasectomy Reversal, and Acquired Epididymal Occlusion

The results of microepididymal sperm aspiration (MESA) combined with IVF and ICSI for obstructive azoospermia are far superior to conventional IVF. ICSI is clearly the treatment of choice for men with surgically non correctable vasoepididymal lesions.

The cryopreservation of sperm in men undergoing MESA or vasectomy reversal should be strongly considered given the success of using thawed spermatozoa for ICSI. This allows more convenient scheduling and helps insure that sperm will be found on the day of the oocyte retrieval.

ICSI with TESE has been used for azoospermic men when no sperm can be recovered from the epididymis, most often with the complete absence of the epididymis or a massively scarred epididymis.

ICSI begins with oocyte retrieval using transvaginal ultrasound guided puncture at the time of optimal follicular development following appropriate hormonal stimulation. After a brief incubation, mature oocytes, those with the first polar body extruded, are candidates for ICSI. Sperm sources include fresh and frozen routine ejaculates, frozen donor specimens, microepididymal sperm aspirates, and testis biopsy.

Micromanipulation procedures are performed using an inverted phase-contrast microscope at 400X. With the sperm and oocytes in the petri dish, a single motile sperm with grossly normal morphology is aspirated tail-first into the injection pipette. The micropipette is pushed through the zona pellucida until the ooplasm is entered. The needle is withdrawn after introduction of the spermatozoa into the oocyte.

After 16 to 18 hours of incubation, the oocytes are examined for the presence of normal fertilization. Embryo transfer is typically performed 3 to 5 days after oocyte harvest. Depending on maternal age and the reproductive endocrinologist’s preferences, generally 2 to 4 of the morphologically best embryos are transferred to the uterus, and any remaining normally cleaving embryos can be cryopreserved.

Determinants of ICSI Success

With even the most severe of male factor sperm defects treatable using ICSI, female factors such as age and oocyte quality are being examined more closely. While the severity of semen abnormalities demonstrate little correlation with ICSI results, egg number and egg quality are now the main determinants of success. Poorer results with ICSI have been observed in women 40 years of age or older, likely due to poorer oocyte quality and diminished oocyte retrieval after ovarian hyperstimulation. Despite concerns with the possibility of an increased risk of birth defects from ICSI, no convincing data have been demonstrated thus far.

 

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