Effects of low concentrations of inhibin B on the outcomes of testicular sperm extraction and intracytoplasmic sperm injection

Predictors of testicular sperm retrieval in patients with non-obstructive azoospermia: a review

Azoospermia is divided into two categories of obstructive azoospermia and non-obstructive azoospermia. Before 1995, couples with a male partner diagnosed with non-obstructive azoospermia had to choose sperm donation or adoption to have a child. Currently, testicular sperm aspiration or micro-dissection testicular sperm extraction combined with intracytoplasmic sperm injection allows patients with non-obstructive azoospermia to have biological offspring. The sperm retrieval rate is significantly higher in micro-dissection testicular sperm extraction compared with testicular sperm aspiration. Additionally, micro-dissection testicular sperm extraction has the advantages of minimal invasion, safety, limited disruption of testicular function, a low risk of postoperative intratesticular bleeding, and low serum testosterone concentrations. Failed micro-dissection testicular sperm extraction has significant emotional and financial implications on the involved couples. Testicular sperm aspiration and micro-dissection testicular sperm extraction have the possibility of failure. Therefore, predicting the sperm retrieval rate before surgery is important. This narrative review summarizes the existing data on testicular sperm aspiration and micro-dissection testicular sperm extraction to identify the possible factor(s) that can predict the presence of sperm to guide clinical practice. The predictors of surgical sperm retrieval in patients with non-obstructive azoospermia have been widely studied, but there is no consensus.

Reproductive Chances of Men with Azoospermia Due to Spermatogenic Dysfunction

Non-obstructive azoospermia (NOA), or lack of sperm in the ejaculate due to spermatogenic dysfunction, is the most severe form of infertility. Men with this form of infertility should be evaluated prior to treatment, as there are various underlying etiologies for NOA. While a significant proportion of NOA men have idiopathic spermatogenic dysfunction, known etiologies including genetic disorders, hormonal anomalies, structural abnormalities, chemotherapy or radiation treatment, infection and inflammation may substantively affect the prognosis for successful treatment. Despite the underlying etiology for NOA, most of these infertile men are candidates for surgical sperm retrieval and subsequent use in intracytoplasmic sperm injection (ICSI). In this review, we describe common etiologies of NOA and clinical outcomes following surgical sperm retrieval and ICSI.

Sperm recovery and ICSI outcomes in men with non-obstructive azoospermia: a systematic review and meta-analysis

BACKGROUND

Factor affecting sperm retrieval rate (SRR) or pregnancy rates (PR) after testicular sperm extraction (TESE) in patients with non-obstructive azoospermia (NOA) have not been systematically evaluated. In addition, although micro-TESE (mTESE) has been advocated as the gold standard for sperm retrieval in men with NOA, its superiority over conventional TESE (cTESE) remains conflicting.

OBJECTIVE AND RATIONALE

The objective was to perform a meta-analysis of the currently available studies comparing the techniques of sperm retrieval and to identify clinical and biochemical factors predicting SRR in men with NOA. In addition, PRs and live birth rates (LBRs), as derived from subjects with NOA post-ICSI, were also analysed as secondary outcomes.

SEARCH METHODS

An extensive Medline, Embase and Cochrane search was performed. All trials reporting SRR derived from cTESE or mTESE in patients with NOA and their specific determinants were included. Data derived from genetic causes of NOA or testicular sperm aspiration were excluded.

OUTCOMES

Out of 1236 studies, 117 studies met the inclusion criteria for this study, enrolling 21 404 patients with a mean age (± SD) of 35.0 ± 2.7 years. cTESE and mTESE were used in 56 and 43 studies, respectively. In addition, 10 studies used a mixed approach and 8 studies compared cTESE with mTESE approach. Overall, a SRR per TESE procedure of 47[45;49]% (mean percentage [95% CI]) was found. No differences were observed when mTESE was compared to cTESE (46[43;49]% for cTESE versus 46[42;49]% for mTESE). Meta-regression analysis demonstrated that SRR per cycle was independent of age and hormonal parameters at enrolment. However, the SRR increased as a function of testis volume. In particular, by applying ROC curve analysis, a mean testis volume higher than 12.5 ml predicted SRR >60% with an accuracy of 86.2% ± 0.01. In addition, SRR decreased as a function of the number of Klinefelter's syndrome cases included (S = -0.02[-0.04;-0.01]; P < 0.01. I = 0.12[-0.05;0.29]; P = 0.16). Information on fertility outcomes after ICSI was available in 42 studies. Overall, a total of 1096 biochemical pregnancies were reported (cumulative PR = 29[25;32]% per ICSI cycle). A similar rate was observed when LBR was analysed (569 live births with a cumulative LBR = 24[20;28]% per ICSI cycle). No influence of male and female age, mean testis volume or hormonal parameters on both PR and LBR per ICSI cycle was observed. Finally, a higher PR per ICSI cycle was observed when the use of fresh sperm was compared to cryopreserved sperm (PR = 35[30;40]%, versus 20[13;29]% respectively): however, this result was not confirmed when cumulative LBR per ICSI cycle was analysed (LBR = 30[20;41]% for fresh versus 20[12;31]% for cryopreserved sperm).

WIDER IMPLICATIONS

This analysis shows that cTESE/mTESE in subjects with NOA results in SRRs of up to 50%, with no differences when cTESE was compared to mTESE. Retrieved sperms resulted in a LBR of up to 28% ICSI cycle. Although no difference between techniques was found, to conclusively clarify if one technique is superior to the other, there is a need for a sufficiently powered and well-designed randomized controlled trial to compare mTESE to cTESE in men with NOA.

Age-dependent inhibin B concentration in relation to FSH and semen sample qualities: a study in 2448 men

Inhibin B is an important serum marker of spermatogenesis, whereas sensitivity and predicting power for the spermatogenic situation at several ages are under debate. We performed a retrospective analysis of data from 2448 men who attended our University-based male infertility clinic to evaluate inhibin B in relation to age and semen sample qualities in comparison with FSH. Moreover, the range of inhibin B in 82 nonobstructive azoospermic patients was correlated with the sperm retrieval in testicular sperm extraction procedures. Inhibin B correlated with FSH (Spearman rank correlation (R)=−0.50; P<0.00001). Inhibin B and inhibin B/FSH ratio (IFR) showed an inverse U-shaped dependence on age, whereas FSH showed a U-shaped dependence on age (optimum 20–40 years). However, in men with normal spermiograms inhibin B concentrations did not differ between age groups. Their levels of inhibin B amounted to 130.5, 54.5–247 ng/l (median, 10th–90th precentile), and of IFR to 38.3, 12.5–104.8 (median, 10th–90th percentile), which might be taken as the reference range. Using the 10th percentile of IFR, correct classification in normal or pathological semen groups was achieved in 99.1%. The percentage of aniline blue-negative spermatozoa, i.e. mature spermatozoa with protamines, did not correlate with FSH (P>0.05) but with inhibin B (R=0.15, P<0.001). The probability of retrieving testicular spermatozoa decreased with declining inhibin B: <20 ng/l sperm could never be found. Our results from a large group of men with a wide spectrum of semen qualities allow estimating reference values for inhibin B and IFR. Inhibin B and especially the IFR are more sensitive markers of male infertility than FSH alone.

Correlation between testicular sperm extraction outcomes and clinical, endocrine and testicular histology parameters in 120 azoospermic men with normal serum FSH levels

We retrospectively evaluated the clinical and hormonal profiles, sperm extraction outcomes and testicular histology parameters in 120 azoospermic men with normal serum follicle-stimulating hormone (FSH) level. Microsurgical epididymal sperm aspiration (MESA) and testicular sperm extraction (TESE) were performed in 33 and 87 cases, respectively. Sperm were successfully retrieved in all the MESA procedures and in 65 of the TESE procedures. The mean serum FSH and inhibin B levels and the testicular volume differed significantly according to whether or not sperm were retrieved. The threshold serum inhibin B value for predicting successful TESE was 123.5pg/mL (sensitivity: 69.7%; specificity: 66.7%). The 13 patients with Sertoli cell only syndrome (SCOS) had a higher mean serum FSH level and a lower mean serum inhibin B level than the other phenotypes. TESE was negative for 11 of the 13 SCOS men. The mean±SD inhibin B level was significantly lower in patients with 5-10IU/L of FSH than those with 2-5IU/L of FSH (108.30±53.86 vs. 175.23±70.17pg/mL, respectively). The sperm retrieval rates were 71.42% for the group with 5-10IU/L of FSH and 87.32% for the group with 2-5IU/L of FSH. Ten of the 13 SCOS men had a FSH level between 5 and 10IU/L. The clinical pregnancy rate was significantly lower (p=0.04) in the group with 5-10IU/L (50%) of FSH than in the group with 2-5IU/L (77.5%) of FSH. In conclusion, there is no FSH value below which spermatogenesis is always found. Inhibin B assays and clinical assessments are thus of particular value in men with normal serum FSH levels.

Serum inhibin-B and follicle stimulating hormone as predictors of the presence of sperm in testicular fine needle aspirate in men with azoospermia

OBJECTIVE

Inhibin-B (Inh-B) is produced by Sertoli cells and controls Follicle Stimulating Hormone (FSH) secretion through a negative feedback mechanism. The primary aim of this study was to compare Iotanh-B with FSH as predictors of the recovery of sperm in testicular fine needle aspirate in men with azoospermia.

DESIGN

In 51 men with azoospermia basal values of Luteinizing Hormone (LH), FSH, prolactin and testosterone as well as Inh-B values before and 24 h and 48 h after the administration of 300 IU recombinant human FSH were determined. Testicular Fine Needle Aspiration (FNA) was also carried out. Thirty-one young healthy men were also enrolled in the study as controls.

RESULTS

There was significant difference between men with azoospermia and controls with regard to the basal Inh-B levels [median (interquartile range) 37.2 (36) vs. 103.0 (90) pg/mL, respectively, p=0.003] but not to the stimulated Inh-B levels [40.5 (41) vs. 73.0 (44) pg/mL, p=0.113 at 24 h and 34.3 (34) vs. 82.0 (50) pg/mL, p=0.098 at 48 h)]. The Area Under Curve in Receiver Operating Characteristic curves were similar for Inh-B and FSH (0.610 vs. 0.716, respectively, p=0.151) as far as prediction of sperm retrieval is concerned.

CONCLUSIONS

Basal serum Inh-B values are significantly lower in men with azoospermia compared to controls. However, Inh-B is not superior to FSH in predicting the presence of sperm in testicular fine needle aspirate.

Microdissection testicular sperm extraction: prediction, outcome, and complications

Testicular spermatozoa can be retrieved successfully by the testicular sperm extraction (TESE) procedure and used for intracytoplasmic sperm injection in cases of non-obstructive azoospermia (NOA). The successful application of TESE depends on the identification of seminiferous tubules containing spermatozoa; testicular tubules of patients with NOA are usually heterogeneous, and TESE may not always be successful in these patients. Microdissection TESE with an operative microscope is advantageous because larger, more opaque, and whitish tubules, presumably containing germ cells with active spermatogenesis, can be identified directly. This procedure is currently the best method for the certain identification of sperm, resulting in a high spermatozoa retrieval rate and minimal postoperative complications. The present review considers the surgical procedure, outcome, prediction for spermatozoa retrieval, and postoperative complications of microdissection TESE.

Significance of inhibin B and anti-Müllerian hormone in seminal plasma: a preliminary study

OBJECTIVE

To evaluate the predictive value of seminal inhibin B and anti-Müllerian hormone (AMH) on the outcome of testicular sperm extraction (TESE) in patients with nonobstructive azoospermia.

DESIGN

Prospective study.

SETTING

Reproductive biology department.

PATIENT(S)

Forty-seven normospermic, 28 oligozoospermic, and 68 azoospermic patients.

INTERVENTION(S)

Testicular sperm extraction.

MAIN OUTCOME MEASURE(S)

Seminal inhibin B and AMH measure.

RESULT(S)

The seminal values of inhibin B and AMH are widely dispersed. Both inhibin B and AMH seminal values are significantly different between the three groups. The average rates of seminal AMH (not inhibin B) differ significantly according to the etiology of the azoospermia. Both seminal markers are correlated. A significant positive correlation could be observed between the seminal inhibin B and the sperm count, but not for AMH. A significant correlation also exists between seminal and serum inhibin B. The predictive value for TESE outcome of each parameter is rather low. Conversely, a logistic regression combining serum FSH, seminal inhibin B, and AMH produced a satisfying area under the curve of 0.985.

CONCLUSION(S)

Seminal inhibin B and AMH values are proposed. Separately, seminal markers are poor predictors of TESE outcome. A logistic regression model led to a satisfying area under the curve of 0.985.

Seminal haploid cell detection by flow cytometry in non-obstructive azoospermia: a good predictive parameter for testicular sperm extraction

BACKGROUND

Testicular sperm extraction (TESE) associated with ICSI gives patients suffering from non-obstructive azoospermia (NOA) the possibility of becoming a father. The success rate of TESE based on sperm recovery is approximately 50%, and the commonly used non-invasive parameters are not predictive enough. Only the invasive testis biopsy has a good prognostic value. The aim of this study was to evaluate the prognostic value of the detection of seminal haploid cells by flow cytometry (FCM) in order to avoid unnecessary testicular biopsy.

METHODS

For 37 NOA patients undergoing testicular biopsy, we measured testis size, serum FSH and inhibin B levels and carried out seminal cytology, seminal FCM analysis and histological examination.

RESULTS

Sperm were found in 18 biopsies. These results were correlated with cytology, FCM analysis and the histological examination. FCM was more sensitive than cytology (100 versus 59%) but less specific (67 versus 83.5%) whereas the histological observation of complete spermatogenesis appeared to be less sensitive (50%) but more specific (100%).

CONCLUSION

Detection of seminal haploid cells by FCM appears to be an interesting non-invasive technique which can predict TESE results and improve the management of NOA patients.

Expression of inhibin α, glial cell line-derived neurotrophic factor and stem cell factor in Sertoli cell-only syndrome: relation to successful sperm retrieval by microdissection testicular sperm extraction

BACKGROUND

Microdissection testicular sperm extraction (TESE) has provided new hope for successful sperm retrieval to patients with Sertoli cell-only syndrome (SCO). We determined expression of the inhibin alpha subunit, glial cell line-derived neurotrophic factor (GDNF) and stem cell factor (SCF) in Sertoli cells obtained from patients with SCO immunohistochemically and compared expression rates with rates of microdissection TESE sperm retrieval.

METHODS

Testicular biopsy specimens were obtained from 52 men with non-obstructive azoospermia who underwent microdissection TESE and were diagnosed with SCO by histological analysis.

RESULTS

All specimens showed intense staining for the inhibin alpha subunit. Moderate or intense staining for GDNF was observed in 65.8% of specimens. All but one showed moderate or intense staining for SCF. Among specimens negative for GDNF, the sperm retrieval rate was significantly higher (100%) for specimens with intense staining for SCF than for specimens with no or moderate staining (30.7%) (P<0.05) for SCF.

CONCLUSION

GDNF expression differs among patients with SCO. The sperm retrieval rate was high in cases of no staining for GDNF and intense staining for SCF.

Inhibins in female and male reproductive physiology: role in gametogenesis, conception, implantation and early pregnancy

A great deal of new information has arisen in the recent years concerning inhibin physiology and clinical relevance in reproductive medicine. It is now recognized that the two inhibin isoforms, named inhibin A and inhibin B, are produced by the gonads in the course of gamete maturation and in women have a different pattern of secretion throughout the menstrual cycle. Since inhibins are also produced by placenta and fetal membranes, it has been suggested that there is an involvement in physiological adaptation of pregnancy. Evidence from several sources has underlined the clinical usefulness of the measurement of inhibin-related proteins in the diagnosis and follow-up of different fertility disturbances and early pregnancy viability. In the male, inhibin B is produced in the testis, principally by the Sertoli cells. Inhibin B expression and secretion are positively correlated with Sertoli cell function, sperm number, and spermatogenic status and are negatively correlated with FSH. This review covers the most recent advances on the role of inhibins in human reproductive function. Considerable progress in the understanding of inhibin physiology has resulted from selective measurement of the two inhibin molecular forms, named inhibin A and B. Newly recognized alterations of inhibin levels in gynaecological diseases as well as in normal and pathological pregnancy are discussed, with particular emphasis on the potential clinical usefulness of assessing inhibin levels in serum and other biological fluids.