In Vitro Fertilization for Male Factor Infertility

MALE FACTOR infertility is a general term that describes couples in whom an inability to conceive is associated with a problem identified in the male partner. This problem may be associated with low sperm production (oligospermia), poor sperm motility (asthenospermia), or abnormal morphology (teratospermia) (1). Abnormal sperm function may also be evaluated with sperm function tests that evaluate sperm interaction with cervical mucus (cervical mucus penetration test), the zona pellucida surrounding the oocyte (hemi-zona binding assay), or the oocyte itself (hamster-egg penetration assay) (2). Male factor infertility also describes men with normal sperm production but conditions that prevent sperm transport to the vagina during intercourse (e.g. reproductive tract obstruction or ejaculatory dysfunction). Obtaining serial semen analyses and questioning of the male partner should be part of the initial survey of an infertile couple. When a male factor is suspected during evaluation of a couple for infertility, complete evaluation of the man is warranted. If treatable conditions causing the male factor are found, they should be corrected. If treatment is unsuccessful, or if the couple still does not conceive, then assisted reproduction is indicated. Assisted reproductive techniques include intrauterine insemination (IUI), in vitro fertilization (IVF), and IVF with micromanipulation. Micromanipulation refers to a series of procedures that enhance the ability of sperm to fertilize an oocyte, in vitro. In this review we will emphasize recent advances in IVF, especially IVF with the advanced micromanipulation technique of intracytoplasmic sperm injection (ICSI), as tools for treatment of the infertile couple with male factor infertility. The cornerstones of evaluation of a subfertile man include a comprehensive history, physical examination, multiple semen analyses, and an endocrine evaluation. In specific circumstances, additional testing may be indicated. For men with azoospermia or severe oligospermia (sperm concentration < 5 × 106/cc), consideration of karyotypic abnormalities such as Klinefelter’s syndrome is appropriate if clinically indicated. In addition, up to 13% of men with azoospermia may have microdeletions of the Y chromosome. Although routine evaluation for these microdeletions is available at only a few U.S. academic centers in 1996, evaluation at the SIMMY protocol referral center (Study of ICSI, Male Infertility and Microdeletions on the Y chromosome) can provide free testing of patients who are candidates for treatment with ICSI (3–6). For men with unilateral or bilateral congenital absence of the vas deferens, cystic fibrosis transmembrane conductance regulator (CFTR) gene analysis is important, as 55–82% of men with congenital absence of the vas deferens will carry detectable CFTR mutations (7). In addition, patients with idiopathic epididymal obstruction have been estimated to have a 47% chance of carrying a detectable CFTR mutation (8). For couples with vasal or epididymal anomalies, testing of the female partner for CFTR mutations is even more important, as not all CFTR mutations are currently detectable in the man. In the case of any other genetic condition, including treatment of men with Klinefelter’s syndrome, and in the case of couples with a female partner over age 40 yr, genetic counselling is recommended before assisted reproduction treatments. Up to 75% of men with a male factor will have identifiable or treatable conditions that affect their fertility (9–11). Nearly all men with male factor infertility are treatable with assisted reproductive techniques. Before applying more invasive techniques, however, avoidance of specific gonadotoxic factors such as exogenous heat, chemical gonadotoxins (e.g. sulfasalazine and cimetidine), or medications that can adversely affect fertilization (including calcium channel blockers) is appropriate. Treatment of varicoceles, endocrine disturbances, symptomatic infections, and obstructive azoospermia have all been demonstrated, using randomized or other appropriately designed studies, to have a role in the management of male infertility (12). Specific treatment of the man may be less invasive, more successful, and more cost effective (13, 14) with lower risk than IVF. In addition, it is worthwhile to remember that up to 1% of men with subfertility have a potentially life threatening condition associated with their fertility problem, (e.g. testis tumor) (1, 15). Suffice it to say that evaluation and treatment of a man with male factor is worthwhile, despite the recent advances in assisted reproduction. Male factor infertility was initially considered a contraindication to IVF because abnormal sperm are less likely to fertilize oocytes than normal sperm (16). However, subsequent experience starting just over a decade ago indicated that fertilizations and subsequent live births were possible despite impaired sperm quality (17). IVF has had some success in the treatment of these men, however it has been recognized that even normal concentrations of sperm from oligozoospermic men, placed directly with oocytes in culture, do not fertilize at the same rates as sperm from otherwise normal men. In addition, adequate numbers of sperm cannot be obtained from all men to allow insemination of oocytes with the usual numbers of gametes (100,000 sperm/oocyte). Initial concerns, that assisted fertilization with apparently defective sperm might lead to the development of abnormal embryos and an increase in the number of birth defects, have not been founded. In fact, once fertilization has been achieved for male factor couples, implantation and subsequent pregnancy appear to be just as likely, if not more likely, to occur than in other cases of IVF (18). Unless advanced age of the female partner is present, IVF is usually indicated after specific treatment of male and female factors affecting fertility has been unsuccessful and less invasive forms of assisted reproduction (intrauterine inseminations) have been attempted. If severe male factor infertility is present, direct treatment with IVF and micromanipulation may be indicated. The technique of IVF is described in greater detail elsewhere (19). Briefly, it involves down-regulation of the woman’s pituitary function with GnRH agonists given during the preceding luteal phase. This is followed by controlled ovarian hyperstimulation using FSH or FSH-stimulating agents, to increase the number of oocytes produced. Follicle development in the ovary is evaluated directly with transvaginal ultrasound imaging of follicular growth and by measurement of serial serum estrogen and progesterone levels. Final oocyte maturation is induced with an intramuscular dose of hCG (5–10,000 units) when optimal follicular development is obtained. Retrieval of oocytes is performed by transvaginal follicular aspiration using ultrasound guidance with intravenous sedation. The transvaginal approach has obviated the need for general anesthesia and laparoscopy to perform IVF. Many oocytes (mean of 12 oocytes) can be obtained from otherwise normal women with ovarian hyperstimulation. Morphologically mature, metaphase II oocytes may then be inseminated with sperm. Human oocytes survive freezing poorly since they are in metaphase; therefore, all retrieved and mature oocytes are inseminated. Immature oocytes may be matured in vitro and subsequently inseminated, although only anecdotal pregnancies have been achieved after in vitro oocyte maturation. Sperm are washed free of seminal fluid and inseminated with oocytes at a concentration of 100,000 or more sperm per oocyte in simulated human (Fallopian) tubal fluid medium, and the oocytes that fertilize (embryos) are usually allowed to divide up to the 8-cell stage before embryo transfer. Embryo transfer back to the uterus is typically performed after 2–3 days of incubation in vitro. Up to four embryos may be transferred to the uterus, and excess embryos may be frozen. An implantation rate can be calculated by dividing the number of gestations (fetal heart on ultrasound) that result from embryo transfer by the number of total number of embryos transferred to the uterus in a population of treated patients. Implantation rates per transferred embryo range from 10–25% in most IVF programs. Gamete micromanipulation has enabled the embryologist to circumvent inefficient steps in the fertilization process. Instead of simply bringing sperm and oocyte together in vitro (IVF), micromanipulation involves mechanical alteration of the oocyte in vitro to increase the chance of fertilization of the oocyte by sperm (Fig. 1.) The three categories of assisted fertilization by gamete micromanipulation that have been applied in humans are illustrated in Fig. 2. The first category involves the creation of an opening in the zona pellucida, an acellular layer surrounding the oocyte that serves as a major barrier to sperm penetration. Subsequently, the micromanipulated oocyte is inseminated according to standard IVF guidelines. These procedures have been broadly termed “zona drilling.” One variant of zona drilling involving mechanical piercing of the zona pellucida has been successful in male factor patients (20). This method has been called partial zona dissection (PZD; Fig. 2A). A second category of micromanipulation techniques directed at facilitating sperm-oocyte interaction is the subzonal insertion of sperm (SuZI). SuZI involves direct placement of sperm into the perivitelline space between the zona pellucida and oocyte, completely bypassing the zona pellucida (Fig. 2B) (2, 21). The third and most invasive form of microsurgical fertilization is the microinjection of a single sperm into the cytoplasm of the oocyte, referred to as intracytoplasmic sperm injection (ICSI; Fig. 2C). This technique for manipulation has a higher risk of oocyte injury than SuZI or PZD, but overall higher fertilization and pregnancy rates (22). Most importantly, only very few sperm are necessary for ICSI. The tremendous superiority of fertilization and pregnancy rates after application of ICSI when compared with PZD and SuZI have relegated both PZD and SuZI to techniques of historical importance only. With micromanipulation, fertilization and pregnancy rates appear to be independent of sperm quality (23, 24), which is the opposite of what has been demonstrated for both IUI and IVF (16). The structural components of an oocyte important for micromanipulation are schematically illustrated. A, Schematic illustration of partial zona dissection technique. B, Schematic illustration of subzonal insertion procedure. C, The intracytoplasmic sperm injection technique is schematically presented. Until recently, the clinical application of direct injection of a single sperm into the cytoplasm of an oocyte during IVF had not been feasible. The demonstration of fertilization and live births by Palermo et al. (25) in 1993 was the first successful application of ICSI. Since that time, ICSI has been performed extensively in multiple centers to treat patients with severe male factor infertility. To date, the success of ICSI procedures has been related to several factors: 1) the viability of the spermatozoon, 2) the quality of the oocyte, 3) effective activation of the oocyte, and 4) ability of the oocyte to tolerate intracytoplasmic manipulation. Application of this treatment is described below. To date, rigorous indications for ICSI are not universally agreed upon. In any condition in which it is that oocyte fertilization might be ICSI should be clinical series applied ICSI in cases men had less than sperm in the less than normal sperm forms or couples have to fertilize any oocytes in an IVF Sperm function tests may provide additional into specific sperm-oocyte interaction that will appropriate candidates for ICSI. have the indications for micromanipulation sperm concentration < × sperm motility < normal morphology < of retrieved of fertilization in a IVF Although fertilization and pregnancy rates with ICSI are to or than achieved with normal sperm in other couples IVF at the same center couples with only semen abnormalities have not been treated with ICSI. the of ICSI, and on it to of this ICSI should not be recommended to couples for whom is as risk to the embryo and may still are by the and with sperm injection is performed on all metaphase II II oocytes have their of on the metaphase the of the metaphase can occur by injury from the injection or by the of a sperm in the oocyte The oocyte is with a and an of the of and for ICSI are described in detail elsewhere single sperm are from a semen and directly into an oocyte in a of The is at the 12 or and the injection the single sperm is the zona pellucida and into the cytoplasm of the oocyte at the of oocytes is to that for oocytes in standard IVF. One of the series using ICSI was from et al. at The in In their on couples who treatment oocytes were and were for a fertilization rate of A total clinical pregnancy rate of was and pregnancy rates from their series are in and clinical pregnancy rates from and clinical pregnancy rates from In Palermo et al. on couples treated with ICSI for IVF or for severe male factor infertility. and pregnancy rates were evaluated to semen and the of the semen successful fertilization in metaphase II oocytes and pregnancies in et al. the of factors on of ICSI in microinjection normal forms in a semen azoospermia or sperm in the pregnancy still be et al. that the only for successful ICSI is the of at to per oocyte in the of the washed semen The only category of semen that had a on fertilization and pregnancy rates with ICSI was when were sperm If motility is present, then viability is impaired as et al. the role of female factors on ICSI in a total of couples, oocytes were with an overall fertilization rate of rates were by but pregnancy rates were lower with rates were and for couples in whom age was less than yr, yr, and 40 or were by et al. with a pregnancy rate for the couples and a 13% pregnancy rate for the couples with the female The rate of for embryos from the oocytes of women over 40 compared with from women less than Implantation of an embryo is These that the chance of a metaphase II oocyte with ICSI is to female but the chance of a pregnancy after transfer of ICSI embryos with female especially female age over 40 activation refers to the series of that occur after sperm-oocyte during which result in the ability of the oocyte to complete to and sperm with the oocyte is during ICSI, other to oocyte activation have been attempted. and fertilization and pregnancy rates during ICSI by aspiration and injection of the oocyte cytoplasm during injection of sperm into the oocyte to oocyte aspiration in an increase in fertilization rates per oocyte from when compared with achieved using only aspiration of the oocyte rates up to with aspiration of cytoplasm additional of oocyte calcium when compared with aspiration calcium have been to have a role in oocyte and these may the by which aspiration fertilization A sperm factor may also have a role in oocyte This sperm factor may need to the sperm to in the oocyte that including of the sperm by the and of the of involves mechanical of the sperm between the injection and the of the the et al. an increase in the of oocytes from with Palermo et al. the of sperm on fertilization rates was in that were retrieved from the and For epididymal Palermo et al. demonstrated an increase in fertilization from per oocyte, with an associated in pregnancy rates from that of may increase sperm which of sperm factors that oocyte activation it is possible that the sperm in of such as of the of activation be induced for optimal success with ICSI. sperm factors as as mechanical of the oocyte are in oocyte of the oocyte to oocyte may occur during ICSI. from some of the major centers ICSI rates of oocyte after injection of Although the for oocyte injury are not it is to occur as a result of and associated with to the during of the oocyte cytoplasm In addition, other factors such as in have been to in the of the human is a for the ICSI procedure. greater is over the first oocyte the oocyte injury rate Palermo et al. have described an oocyte of during ICSI. The oocytes with this not form a normal during penetration of the injection but the oocyte With a oocyte injury rate was compared with a injury rate for other were more likely to be retrieved from women treated with higher treatment with lower serum at or the oocytes were maturation in vitro. These that ovarian hyperstimulation may affect the ability of oocytes to survive ICSI of ICSI include general of IVF as as the specific related to the micromanipulation of ICSI. One of the most associated with of the is the ovarian hyperstimulation syndrome This can as ovarian by follicular or ovarian and The syndrome in a form for of and in a severe form for of the population controlled ovarian hyperstimulation. of ovarian hyperstimulation are pituitary and of ovarian have been for transvaginal aspiration as as associated with transvaginal aspiration have been in of cases and include infections, and include and The are higher in ovarian procedures than in other pregnancies from ovarian are at risk for pregnancy and multiple gestations The rate of after a pregnancy with assisted reproduction is These are to advanced age and the associated of a higher rate of pregnancy from multiple and of these pregnancies because of a clinical pregnancy of at heart on the chance of a for ICSI from pregnancies occur in up to of and can be life The is usually and tubal from or pregnancies occur in of cases of IVF with embryo transfer and of ICSI cases in the pregnancies are considered a of assisted reproductive techniques because of the associated of of and Most importantly, multiple gestations are universally associated with and the associated to including and with or To prevent pregnancies and their it be to assisted reproduction it is indicated and to the number of embryos is of IVF, including and transfer of only three or embryos is and pregnancies are less is to transfer more than three embryos by couples in the who are to In for women less than of only three embryos should be The of to possible genetic in men with severe male infertility, and the of abnormal sperm for intracytoplasmic sperm injection has over the of ICSI on the genetic of the have increase in birth rates when IVF was to increase in the congenital rate in their center after ICSI when compared with the general after ICSI had major congenital compared with in the general population and of from IVF ICSI abnormalities have also been in ICSI et al. on 12 patients with ICSI pregnancies who for advanced of the 12 women had pregnancies for a total of procedures by or A total of 5 abnormalities were cases of and cases of This rate of abnormalities has not been by other The on a total of performed in pregnancies by ICSI. 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Although rates in after assisted reproductive procedures have not in the general experience with these techniques is genetic and of the also be available to couples in assisted reproductive programs. couples micromanipulation procedures are to have with or The need for is on the couple the pregnancy if the are If the couple carry a pregnancy to term of the of then the of carry to the and cannot be The application of ICSI has allowed treatment of couples who very were considered and with bilateral congenital absence of the vas deferens and other of the male reproductive tract are candidates for ICSI. 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