Resumo em Inglês:

The integrity of the sperm genome and epigenome are critical for normal embryonic development. The advent of assisted reproductive technology has led to an increased understanding of the role of sperm in fertilization and embryogenesis. During fertilization, the sperm transmits not only nuclear DNA to the oocyte but also activation factor, centrosomes, and a host of messenger RNA and microRNAs. This complex complement of microRNAs and other non-coding RNAs is believed to modify important post-fertilization events. Thus, the health of the sperm genome and epigenome is critical for improving assisted conception rates and the birth of healthy offspring.

Resumo em Inglês:

The misconception that infertility is typically associated with the female is commonly faced in the management of infertile men. It is uncommon for a patient to present for an infertility evaluation with an abnormal semen analysis report before an extensive female partner workup has been performed. Additionally, a man is usually considered fertile based only on seminal parameters without a physical exam. This behavior may lead to a delay in both the exact diagnosis and in possible specific infertility treatment. Moreover, male factor infertility can result from an underlying medical condition that is often treatable but could possibly be life-threatening. The responsibility of male factor in couple's infertility has been exponentially rising in recent years due to a comprehensive evaluation of reproductive male function and improved diagnostic tools. Despite this improvement in diagnosis, azoospermia is always the most challenging topic associated with infertility treatment. Several conditions that interfere with spermatogenesis and reduce sperm production and quality can lead to azoospermia. Azoospermia may also occur because of a reproductive tract obstruction. Optimal management of patients with azoospermia requires a full understanding of the disease etiology. This review will discuss in detail the epidemiology and etiology of azoospermia. A thorough literature survey was performed using the Medline, EMBASE, BIOSIS, and Cochrane databases. We restricted the survey to clinical publications that were relevant to male infertility and azoospermia. Many of the recommendations included are not based on controlled studies.

Resumo em Inglês:

Approximately 1% of all men in the general population suffer from azoospermia, and azoospermic men constitute approximately 10 to 15% of all infertile men. Thus, this group of patients represents a significant population in the field of male infertility. A thorough medical history, physical examination and hormonal profile are essential in the evaluation of azoospermic males. Imaging studies, a genetic workup and a testicular biopsy (with cryopreservation) may augment the workup and evaluation. Men with nonobstructive azoospermia should be offered genetic counseling before their spermatozoa are used for assisted reproductive techniques. This article provides a contemporary review of the evaluation of the azoospermic male.

Resumo em Inglês:

Azoospermia is a descriptive term referring to ejaculates that lack spermatozoa without implying a specific underlying cause. The traditional definition of azoospermia is ambiguous, which has ramifications on the diagnostic criteria. This issue is further compounded by the apparent overlap between the definitions of oligospermia and azoospermia. The reliable diagnosis of the absence of spermatozoa in a semen sample is an important criterion not only for diagnosing male infertility but also for ascertaining the success of a vasectomy and for determining the efficacy of hormonal contraception. There appears to be different levels of rigor in diagnosing azoospermia in different clinical situations, which highlights the conflict between scientific research and clinical practice in defining azoospermia.

Resumo em Inglês:

Azoospermia due to obstructive and non-obstructive mechanisms is a common manifestation of male infertility accounting for 10-15% of such cases. Known genetic factors are responsible for approximately 1/3 of cases of azoospermia. Nonetheless, at least 40% of cases are currently categorized as idiopathic and may be linked to unknown genetic abnormalities. It is recommended that various genetic screening tests are performed in azoospermic men, given that their results may play vital role in not only identifying the etiology but also in preventing the iatrogenic transmission of genetic defects to offspring via advanced assisted conception techniques. In the present review, we examine the current genetic information associated with azoospermia based on results from search engines, such as PUBMED, OVID, SCIENCE DIRECT and SCOPUS. We also present a critical appraisal of use of genetic testing in this subset of infertile patients.

Resumo em Inglês:

Obstructive azoospermia is a common cause of male infertility and can result from infection, congenital anomalies, or iatrogenic injury. Microsurgical vasal reconstruction is a suitable treatment for many cases of obstructive azoospermia, although some couples will require sperm retrieval paired with in-vitro fertilization. The various causes of obstructive azoospermia and recommended treatments will be examined. Microsurgical vasovasostomy and vasoepididymostomy will be discussed in detail. The postoperative patency and pregnancy rates for surgical reconstruction of obstructive azoospermia and the impact of etiology, obstructive interval, sperm granuloma, age, and previous reconstruction on patency and pregnancy will be reviewed.

Resumo em Inglês:

Non-obstructive azoospermia is diagnosed in approximately 10% of infertile men. It represents a failure of spermatogenesis within the testis and, from a management standpoint, is due to either a lack of appropriate stimulation by gonadotropins or an intrinsic testicular impairment. The former category of patients has hypogonadotropic hypogonadism and benefits from specific hormonal therapy. These men show a remarkable recovery of spermatogenic function with exogenously administered gonadotropins or gonadotropin-releasing hormone. This category of patients also includes some individuals whose spermatogenic potential has been suppressed by excess androgens or steroids, and they also benefit from medical management. The other, larger category of non-obstructive azoospermia consists of men with an intrinsic testicular impairment where empirical medical therapy yields little benefit. The primary role of medical management in these men is to improve the quantity and quality of sperm retrieved from their testis for in vitro fertilization. Gonadotropins and aromatase inhibitors show promise in achieving this end point.

Resumo em Inglês:

Impaired testicular function, i.e., hypogonadism, can result from a primary testicular disorder (hypergonadotropic) or occur secondary to hypothalamic-pituitary dysfunction (hypogonadotropic). Hypogonadotropic hypogonadism can be congenital or acquired. Congenital hypogonadotropic hypogonadism is divided into anosmic hypogonadotropic hypogonadism (Kallmann syndrome) and congenital normosmic isolated hypogonadotropic hypogonadism (idiopathic hypogonadotropic hypogonadism). The incidence of congenital hypogonadotropic hypogonadism is approximately 1-10:100,000 live births, and approximately 2/3 and 1/3 of cases are caused by Kallmann syndrome (KS) and idiopathic hypogonadotropic hypogonadism, respectively. Acquired hypogonadotropic hypogonadism can be caused by drugs, infiltrative or infectious pituitary lesions, hyperprolactinemia, encephalic trauma, pituitary/brain radiation, exhausting exercise, abusive alcohol or illicit drug intake, and systemic diseases such as hemochromatosis, sarcoidosis and histiocytosis X. The clinical characteristics of hypogonadotropic hypogonadism are androgen deficiency and a lack/delay/stop of pubertal sexual maturation. Low blood testosterone levels and low pituitary hormone levels confirm the hypogonadotropic hypogonadism diagnosis. A prolonged stimulated intravenous GnRH test can be useful. In Kallmann syndrome, cerebral MRI can show an anomalous morphology or even absence of the olfactory bulb. Therapy for hypogonadotropic hypogonadism depends on the patient's desire for future fertility. Hormone replacement with testosterone is the classic treatment for hypogonadism. Androgen replacement is indicated for men who already have children or have no desire to induce pregnancy, and testosterone therapy is used to reverse the symptoms and signs of hypogonadism. Conversely, GnRH or gonadotropin therapies are the best options for men wishing to have children. Hypogonadotropic hypogonadism is one of the rare conditions in which specific medical treatment can reverse infertility. When an unassisted pregnancy is not achieved, assisted reproductive techniques ranging from intrauterine insemination to in vitro fertilization to the acquisition of viable sperm from the ejaculate or directly from the testes through testicular sperm extraction or testicular microdissection can also be used, depending on the woman's potential for pregnancy and the quality and quantity of the sperm.

Resumo em Inglês:

The literature on male reproductive medicine is continually expanding, especially regarding the diagnosis and treatment of infertility due to non-obstructive azoospermia. The advent of in vitro fertilization with intracytoplasmic sperm injection has dramatically improved the treatment of male infertility due to nonobstructive azoospermia. Assisted reproduction using testicular spermatozoa has become a treatment of hope for men previously thought to be incapable of fathering a child due to testicular failure. In addition, numerous studies on non-obstructive azoospermia have reported that varicocelectomy not only can induce spermatogenesis but can also increase the sperm retrieval rate; however, the value of varicocelectomy in patients with non-obstructive azoospermia still remains controversial. The purpose of this review is to present an overview of the current status of varicocele repair in men with non-obstructive azoospermia.

Resumo em Inglês:

The use of non-ejaculated sperm coupled with intracytoplasmic sperm injection has become a globally established procedure for couples with azoospermic male partners who wish to have biological offspring. Surgical methods have been developed to retrieve spermatozoa from the epididymides and the testes of such patients. This article reviews the methods currently available for sperm acquisition in azoospermia, with a particular focus on the perioperative, anesthetic and technical aspects of these procedures. A critical analysis of the advantages and disadvantages of these sperm retrieval methods is provided, including the authors' methods of choice and anesthesia preferences.

Resumo em Inglês:

Obstructive azoospermia is a relatively common male infertility condition. The main etiologies of obstructive azoospermia include congenital, surgical-derived, traumatic and post-infectious cases. Although seminal tract reconstruction is a cost-effective treatment in most cases, this approach may not be feasible or desired in some cases. In such cases, assisted reproduction techniques offer a method for achieving pregnancy, notably via sperm retrieval and intracytoplasmic sperm injection. This process requires several considerations and decisions to be made, including the cause and duration of obstruction, which sperm retrieval technique to use, and whether to use fresh or frozen-thawed sperm. We present a review of obstructive azoospermia and assisted reproduction techniques, highlighting the most relevant aspects of the decision-making process for use in clinical practice.

Resumo em Inglês:

Testicular sperm retrieval techniques associated with intracytoplasmic sperm injection have changed the field of male infertility treatment and given many azoospermic men the chance to become biological fathers. Despite the current use of testicular sperm extraction, reliable clinical and laboratory prognostic factors of sperm recovery are still absent. The objective of this article was to review the prognostic factors and clinical use of sperm retrieval for men with non-obstructive azoospermia. The PubMed database was searched for the Medical Subject Headings (MeSH) terms azoospermia, sperm retrieval, and prognosis. Papers on obstructive azoospermia were excluded. The authors selected articles that reported successful sperm retrieval techniques involving clinical, laboratory, or parenchyma processing methods. The selected papers were reviewed, and the prognostic factors were discussed. No reliable positive prognostic factors guarantee sperm recovery for patients with non-obstructive azoospermia. The only negative prognostic factor is the presence of AZFa and AZFb microdeletions.

Resumo em Inglês:

There are two main reasons why sperm may be absent from semen. Obstructive azoospermia is the result of a blockage in the male reproductive tract; in this case, sperm are produced in the testicle but are trapped in the epididymis. Non-obstructive azoospermia is the result of severely impaired or non-existent sperm production. There are three different sperm-harvesting procedures that obstructive azoospermic males can undergo, namely MESA (microsurgical epididymal sperm aspiration), PESA (percutaneous epididymal sperm aspiration), and TESA (testicular sperm aspiration). These three procedures are performed by fine-gauge needle aspiration of epididymal fluid that is examined by an embryologist. Additionally, one technique, called TESE (testicular sperm extraction), is offered for males with non-obstructive azoospermia. In this procedure, a urologist extracts a piece of tissue from the testis. Then, an embryologist minces the tissue and uses a microscope to locate sperm. Finding sperm in the testicular tissue can be a laborious 2- to 3-hour process depending on the degree of sperm production and the etiology of testicular failure. Sperm are freed from within the seminiferous tubules and then dissected from the surrounding testicular tissue. It is specifically these situations that require advanced reproductive techniques, such as ICSI, to establish a pregnancy. This review describes eight different lab processing techniques that an embryologist can use to harvest sperm. Additionally, sperm cryopreservation, which allows patients to undergo multiple ICSI cycles without the need for additional surgeries, will also be discussed.

Resumo em Inglês:

The introduction of the technique of intracytoplasmic sperm injection to achieve fertilization, especially using surgically retrieved testicular or epididymal sperm from men with obstructive or non-obstructive azoospermia, has revolutionized the field of assisted reproduction. The techniques for the retrieval of spermatozoa vary from relatively simple percutaneous sperm aspiration to open excision (testicular biopsy) and the more invasive Micro-TESE. The probability of retrieving spermatozoa can be as high as 100% in men with obstructive azoospermia (congenital bilateral absence of the vas deferens, status post-vasectomy). However, in nonobstructive azoospermia, successful sperm retrieval has been reported in 10-100% of cases by various investigators. The surgical retrieval and cryopreservation of sperm, especially in men with non-obstructive azoospermia, to some extent ensures the availability of sperm at the time of intracytoplasmic sperm injection. In addition, this strategy can avoid unnecessary ovarian stimulation in those patients intending to undergo in vitro fertilization-intracytoplasmic sperm injection with freshly retrieved testicular sperm when an absolute absence of sperm in the testis is identified. Several different methods for the cryopreservation of testicular and epididymal sperm are available. The choice of the container or carrier may be an important consideration and should take into account the number or concentration of the sperm in the final preparation. When the number of sperm in a testicular biopsy sample is extremely low (e.g., 1-20 total sperm available), the use of an evacuated zona pellucida to store the cryopreserved sperm has been shown to be an effective approach.

Resumo em Inglês:

We compared pregnancy outcomes following intracytoplasmic sperm injection for the treatment of male infertility according to the type of azoospermia. First, we analyzed our data from 370 couples who underwent intracytoplasmic sperm injection using sperm from men with obstructive azoospermia and nonobstructive azoospermia, and the outcomes were compared to a group of 465 non-azoospermic infertile males. Then, we performed a systematic review of the published data on pregnancy and neonatal outcomes of children born after sperm injection using sperm from men with obstructive and nonobstructive azoospermia. Live birth rates were significantly lower in the nonobstructive azoospermia group (21.4%) compared with the obstructive azoospermia (37.5%) and ejaculated sperm (32.3%) groups. A total of 326 live births resulted in 427 babies born. Differences were not observed between the groups in gestational age, preterm birth, birth weight and low birth weight, although we noted a tendency towards poorer neonatal outcomes in the azoospermia categories. The overall perinatal death and malformation rates were 2.8% and 1.6%, respectively, and the results did not differ between the groups. We identified 20 published studies that directly compared pregnancy outcomes between obstructive azoospermia and nonobstructive azoospermia. Most of these studies were not designed to detect differences in live birth rates and had lower power to detect differences in less frequent outcomes, and the reporting of neonatal outcomes was unusual. The included studies reported either a decrease or no difference in pregnancy outcomes with intracytoplasmic sperm injection in cases of nonobstructive azoospermia and obstructive azoospermia. In general, no major differences were noted in short-term neonatal outcomes and congenital malformation rates between children from fathers with nonobstructive azoospermia and obstructive azoospermia.

Resumo em Inglês:

Intracytoplasmic injection with testicular spermatozoa has become a routine treatment in fertility clinics. Spermatozoa can be recovered in half of patients with nonobstructive azoospermia. The use of immature germ cells for intracytoplasmic injection has been proposed for cases in which no spermatozoa can be retrieved. However, there are low pregnancy rates following intracytoplasmic injection using round spermatids from men with no elongated spermatids or spermatozoa in their testes. The in vitro culture of immature germ cells to more mature stages has been proposed as a means to improve this poor outcome. Several years after the introduction of intracytoplasmic injection with elongating and round spermatids, uncertainty remains as to whether this approach can be considered a safe treatment option. This review outlines the clinical and scientific data regarding intracytoplasmic injection using immature germ cells and in vitro matured germ cells.

Resumo em Inglês:

Aspermatogenesis is a severe impairment of spermatogenesis in which germ cells are completely lacking or present in an immature form, which results in sterility in approximately 25% of patients. Because assisted reproduction techniques require mature germ cells, biotechnology is a valuable tool for rescuing fertility while maintaining biological fatherhood. However, this process involves, for instance, the differentiation of preexisting immature germ cells or the production/derivation of sperm from somatic cells. This review critically addresses four potential techniques: sperm derivation in vitro, germ stem cell transplantation, xenologous systems, and haploidization. Sperm derivation in vitro is already feasible in fish and mammals through organ culture or 3D systems, and it is very useful in conditions of germ cell arrest or in type II Sertoli-cell-only syndrome. Patients afflicted by type I Sertoli-cell-only syndrome could also benefit from gamete derivation from induced pluripotent stem cells of somatic origin, and human haploid-like cells have already been obtained by using this novel methodology. In the absence of alternative strategies to generate sperm in vitro, in germ cells transplantation fertility is restored by placing donor cells in the recipient germ-cell-free seminiferous epithelium, which has proven effective in conditions of spermatogonial arrest. Grafting also provides an approach for ex-vivo generation of mature sperm, particularly using prepubertal testis tissue. Although less feasible, haploidization is an option for creating gametes based on biological cloning technology. In conclusion, the aforementioned promising techniques remain largely experimental and still require extensive research, which should address, among other concerns, ethical and biosafety issues, such as gamete epigenetic status, ploidy, and chromatin integrity.