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      Review of Azoospermia

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          Abstract

          Azoospermia is classified as obstructive azoospermia (OA) or non-obstructive azoospermia (NOA), each having very different etiologies and treatments. The etiology, diagnosis, and management of azoospermia were reviewed and relevant literature summarized. Differentiation between these two etiologies is of paramount importance and is contingent upon thorough history and physical examination and indicated laboratory/genetic testing. OA occurs secondary to obstruction of the male reproductive tract, and is diagnosed through a combination of history/physical examination, laboratory testing, genetics (CFTR for congenital OA), and imaging studies. NOA (which includes primary testicular failure and secondary testicular failure) is differentiated from OA by clinical assessment (testis consistency/volume), laboratory testing (FSH), and genetic testing (karyotype, Y chromosome microdeletion, or specific genetic testing for hypogonadotropic hypogonadism). For obstructive azoospermia, management includes microsurgical reconstruction when feasible using microsurgical vasovasostomy or vasoepididymostomy. Microsurgical epididymal sperm aspiration with in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) is utilized for those cases not amenable to reconstruction. NOA management includes medical management for congenital hypogonadotropic hypogonadism and microdissection testicular sperm extraction with IVF/ICSI for appropriate candidates based on laboratory/genetic testing. Overall, this important review provides an updated summary of the most recent available literature describing etiology, diagnosis, and management of azoospermia.

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          Evaluation of the azoospermic patient.

          Azoospermia is found in up to 10 to 20 per cent of the men who present to an infertility clinic. The main causes are testicular failure and ductal obstruction. Testicular biopsy remains the definitive test used to differentiate these 2 disorders. A retrospective study of 133 azoospermic men was performed to determine the accuracy and limitations of noninvasive variables in predicting testicular failure in an effort to limit the need for diagnostic testicular biopsy. Of 49 patients (37 per cent) with ductal obstruction a third had bilateral vasal agenesis. The remaining 84 azoospermic patients (63 per cent) had testicular failure. The results of the complete evaluation of these patients are described. Among the 101 patients with a testicular biopsy confirmed diagnosis there was a significant difference in testicular size (p less than 0.001), ejaculate volume (p less than 0.001) and serum follicle-stimulating hormone (p less than 0.001) between patients with testicular failure and those with ductal obstruction. The sensitivity and specificity of various parameters were determined. The best criteria to predict ductal obstruction preoperatively are a serum follicle-stimulating hormone level of less than 2 times greater than normal and the absence of bilateral testicular atrophy (100 per cent sensitivity and 71 per cent specificity). An algorithm for evaluation of the azoospermic patient is described such that all men with ductal obstruction and a minimal number with testicular failure undergo testicular biopsy.
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            Testicular sperm extraction: microdissection improves sperm yield with minimal tissue excision.

            Testicular sperm extraction (TESE) is often an effective method for sperm retrieval from men with non-obstructive azoospermia. However, TESE has been a blind procedure that does not identify the focal sperm-producing areas of the testicle until after tissue has been excised from the patient. Experience with a new technique of microdissection of testicular tubules is presented here that identifies sperm-containing regions before their removal. Identification of spermatogenically active regions of the testicle is possible by direct examination of the individual seminiferous tubules. The underlying concept for this technique is simple: seminiferous tubules containing many developing germ cells, rather than Sertoli cells alone, are likely to be larger and more opaque than tubules without sperm production. In a sequential series of TESE cases for men with non-obstructive azoospermia, the ability to find spermatozoa increased from 45% (10/22) to 63% (17/27) after introduction of the microdissection technique. Microdissected samples yielded an average of 160,000 spermatozoa per sample in only 9.4 mg of tissue, whereas only 64,000 spermatozoa were found in standard biopsy samples that averaged 720 mg in weight (P < 0.05 for all comparisons). For men where microdissection was attempted, successful identification of enlarged tubules was possible in 56% (15/27) of cases. However, spermatozoa were retrieved with microdissection TESE for six men in whom sperm retrieval was unsuccessful with standard TESE approaches (35% of all men with spermatozoa retrieved). These findings suggest that microdissection TESE can improve sperm retrieval for men with non-obstructive azoospermia over that achieved with previously described biopsy techniques.
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              A survey of small RNAs in human sperm.

              There has been substantial interest in assessing whether RNAs (mRNAs and sncRNAs, i.e. small non-coding) delivered from mammalian spermatozoa play a functional role in early embryo development. While the cadre of spermatozoal mRNAs has been characterized, comparatively little is known about the distribution or function of the estimated 24,000 sncRNAs within each normal human spermatozoon. RNAs of <200 bases in length were isolated from the ejaculates from three donors of proved fertility. RNAs of 18-30 nucleotides in length were then used to construct small RNA Digital Gene Expression libraries for Next Generation Sequencing. Known sncRNAs that uniquely mapped to a single location in the human genome were identified. Bioinformatic analysis revealed the presence of multiple classes of small RNAs in human spermatozoa. The primary classes resolved included microRNA (miRNAs) (≈ 7%), Piwi-interacting piRNAs (≈ 17%), repeat-associated small RNAs (≈ 65%). A minor subset of short RNAs within the transcription start site/promoter fraction (≈ 11%) frames the histone promoter-associated regions enriched in genes of early embryonic development. These have been termed quiescent RNAs. A complex population of male derived sncRNAs that are available for delivery upon fertilization was revealed. Sperm miRNA-targeted enrichment in the human oocyte is consistent with their role as modifiers of early post-fertilization. The relative abundance of piRNAs and repeat-associated RNAs suggests that they may assume a role in confrontation and consolidation. This may ensure the compatibility of the genomes at fertilization.
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                Author and article information

                Journal
                Spermatogenesis
                Spermatogenesis
                SPMG
                Spermatogenesis
                Landes Bioscience
                2156-5554
                2156-5562
                31 March 2014
                2014
                : 4
                : e28218
                Affiliations
                [1 ]Department of Urology and Institute for Reproductive Medicine; Weill Cornell Medical College of Cornell University; New York, NY USA
                [2 ]F.A.C.S
                [3 ]Director of the Center for Male Reproductive Medicine and Microsurgery; Weill Cornell Medical College of Cornell University; New York, NY USA
                [4 ]Center for Biomedical Research; The Population Council; New York, NY, USA
                Author notes
                [* ]Correspondence to: Matthew Wosnitzer, Email: maw7011@ 123456med.cornell.edu
                Article
                2014SPGEN0001R 28218
                10.4161/spmg.28218
                4124057
                25105055
                d89da223-07f3-4eac-a933-a76f563d6101
                Copyright © 2014 Landes Bioscience

                This is an open-access article licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. The article may be redistributed, reproduced, and reused for non-commercial purposes, provided the original source is properly cited.

                History
                : 12 January 2014
                : 13 February 2014
                : 13 February 2014
                Categories
                Review

                Human biology
                azoospermia,male infertility,microdissection testicular sperm extraction,microsurgical epididymal sperm aspiration,non-obstructive azoospermia,obstructive azoospermia,vasectomy reversal,vasoepididymostomy,vasovasostomy

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