Male Infertility - Assisted Reproductive Technologies

If neither surgery nor medical therapy is appropriate for male infertility treatment, assisted reproductive techniques can be used to achieve a pregnancy.

Intrauterine Insemination

Intrauterine insemination (IUI) involves the placement of a washed pellet of ejaculated sperm within the female uterus, beyond the cervical barrier. The principal indication for IUI is for a cervical factor; if the cervix is bypassed, then pregnancies may ensue. IUI is also used for low sperm quality, for immunologic infertility, and in men with mechanical problems of sperm delivery (eg, hypospadias). There should be at least 5-40 million motile sperm in the ejaculate (volume × concentration × motility) to make this procedure worthwhile. Success rates vary widely and are directly related to female reproductive potential; given this, pregnancy rates of 8-16% per cycle have been reported with IUI as a treatment for male infertility. Success rates are improved if ultrasound is used to document that follicles are enlarging and if urine testing is used to predict ovulation precisely.

In Vitro Fertilization and ICSI (Figure 42-17)

In vitro fertilization is a more complex technique than IUI and removes even more of the formidable obstacles to sperm in the female reproductive tract. It involves controlled ovarian stimulation and ultrasound-guided transvaginal egg retrieval from the ovaries before normal ovulation. Eggs are then fertilized in petri dishes with anywhere from 500,000 to 5 million motile sperm. This is excellent technology with which to bypass moderate to severe forms of male infertility in which low numbers of motile sperm are present. Most recently, a revolutionary addition to IVF has been described that is referred to as sperm micromanipulation, or ICSI. The sperm requirement for egg fertilization has dropped from hundreds of thousands for IVF to 1 viable sperm for ICSI. This has led to the development of aggressive new surgical techniques to provide sperm for egg fertilization from men with apparent azoospermia (no ejaculated sperm). The availability of these techniques has pushed urologists to look beyond the ejaculate and into the male reproductive tract to find sperm for biologic pregnancies. At present, sources of sperm include the vas deferens, epididymis, and testicle. Two notes of concern are the following: (1) Since IVF and ICSI may eliminate many natural selection barriers that exist during natural fertilization, genetic defects that caused the infertility are expected to be passed on to offspring unabated. This has large ethical implications, especially with respect to X-linked diseases like Klinefelter syndrome that might be expected to resurface again in grandchildren of the affected but treatable infertile male. (2) Recent data show that offspring born to infertile couples with this technique have a 4-fold higher incidence of sex chromosomal anomalies than do children who are naturally conceived.

Preimplantation Genetic Diagnosis

Preimplantation genetic diagnosis is a highly specialized technique that enables the laboratory to precisely define the genetic normality of embryos. In patients with heritable, possibly life-threatening diseases, it is possible that offspring conceived with IVF and ICSI may have these diseases transmitted to them. This complex technique involves the removal of single cells from the early embryo while it is grown in petri dishes before transfer to the uterus. The genetic material from these “biopsied” cells can then be examined to determine whether the embryo carries an abnormal chromosome or gene. Through preimplantation genetic diagnosis, early human embryos that result from IVF and ICSI can be individually examined as they develop for the presence or absence of suspected genetic traits. Because of the real-time nature of the technique, decisions regarding embryo transfer are made within 24 h and help ensure that lethal diseases are not transmitted to offspring. Remarkably, the removal of a few cells from the embryo is not detrimental to the survival and normal development of most embryos.

REFERENCES

RELATED STORIES:
Male reproductive physiology - Fertilization   Vasovasostomy - Surgical Treatments of Male infertility   Disorders of Sperm Function or Motility   Disorders of Coitus - Causes of Male infertility   Laboratory Diagnosis of Male Infertility   Adjunctive Tests - Diagnosis of Male Infertility   Diagnosis of Male Infertility - Hormone Assessment   Posttesticular Causes of Male infertility   Causes of Male infertility   Testis Biopsy & Vasography - Diagnosis of Male Infertility   Treatment of Male infertility   Nonsurgical Treatments of Male infertility   Causes of Male infertility - Gonadotoxins   Ejaculatory Duct Obstruction - Surgical Treatments of Male infertility   Male Infertility - Empiric Medical Therapy

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