Laboratory Studies
Men undergoing evaluation for infertility typically undergo hormonal evaluation with follicle-stimulating hormone (FSH) and testosterone studies. Luteinizing hormone (LH) and prolactin testing are not routinely necessary. In addition, routine testing for male infertility includes at least two semen analyses. Results are as follows:
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Plasma testosterone levels are typically normal.
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Azoospermia and an elevated serum FSH level (>2-3 times reference range) indicate spermatogenic failure.
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Azoospermia and a serum FSH level within the reference range suggest possible spermatogenic failure or an obstruction.
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The serum FSH level is typically (90%) elevated. Elevations of greater than 2.5-3 times the reference range are diagnostic for spermatogenic failure.
In its purest sense, Sertoli-cell-only (SCO) syndrome must present as azoospermia; however, a minority of men with the syndrome have foci of spermatogenesis in a testis that is predominantly SCO.
If a couple is considering intracytoplasmic sperm injection (ICSI), a micromanipulation technique in which a single sperm is injected into an oocyte, they should be offered genetic testing with a Y-chromosome microdeletion assay and karyotyping.
Other Tests
Azoospermia should be documented with a semen pellet analysis. The semen pellet is performed by centrifuging a grossly azoospermic semen specimen for 10 minutes at 1500-2000 rpm. This pellet is considered standard for the diagnosis of azoospermia. The pellet at the bottom of the conical tube is examined under a microscope at a magnification of 400X. If sperm are identified, then patchy spermatogenesis within the testes is present.
Men with SCO syndrome who are azoospermic are at an increased risk of testicular nodules and cancer. As such, the roles of clinical evaluation, ultrasonography, and biopsy should be emphasized. [15]
Histologic Findings
Germinal cell aplasia (SCO syndrome) is histologically characterized by seminiferous tubules that contain only Sertoli cells, with a complete absence of all germ cells. In most cases, the tunica propria and basement membranes are not thickened appreciably, and the tubules are normal or slightly decreased in diameter. The interstitium contains normal numbers of Leydig cells. One may observe a patient with an otherwise classic example of germinal cell aplasia who has an occasional tubule with some degree of spermatogenesis. Levin has classified this as germinal cell aplasia and focal spermatogenesis.
Biopsy
The testis biopsy is the criterion standard for diagnosis of SCO syndrome. Most urologists are familiar with the open biopsy technique. This technique may be performed with a local cord block in most men. Alternatively, a general anesthetic may be used. A small biopsy sample is taken from the surface of the testis and placed in Bouin fixative. Findings on testicular biopsy may include severe hypospermatogenesis, maturation arrest-spermatid stage, maturation arrest-spermatocyte stage, or SCO syndrome.
Men may be offered a testis biopsy to define whether an obstruction or spermatogenic failure is present. If the serum FSH level is greater than 2.5-3 times the reference range and intracytoplasmic sperm injection (ICSI) is not a consideration, the biopsy findings would not change the management plan. If the couple is considering ICSI, a diagnostic biopsy may be helpful to provide counseling regarding the possibility of finding sperm at the time of ICSI. If spermatogenic failure is predominant and rare sperm are identified, testicular extraction of sperm with ICSI may be possible at a later time. At the time of testis biopsy, a specimen may be cryopreserved for potential use of any sperm at a later time.
Some investigators discuss the use of fine-needle aspiration cytology (FNAC) prior to biopsy as a less invasive means of establishing a diagnosis. In addition, this technique can offer prognostic information regarding the likelihood of successful testicular sperm extraction (TESE). [16]
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This hematoxylin and eosin section of a testis biopsy (400X) demonstrates an individual tubule lined only with Sertoli cells (Sertoli-cell-only [SCO] syndrome). The Sertoli cells line the seminiferous tubule.
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Interaction between the hypothalamus and the testes. Courtesy of Wikispaces at https://malereprobio12.wikispaces.com/.
