FNA mapping
[1] As an alternative to open testicular biopsy for the last 40 years, FNA mapping has helped to characterize states of human male infertility due to defective spermatogenesis.
Advances in assisted reproductive technology (ART) have revolutionized the ability to help men with even the severest forms of male infertility to become fathers.
This technique involves controlled ovarian stimulation followed by egg retrieval, in vitro fertilization, and embryo transfer to the uterus.
[7] From a contemporary search of the English literature, it is apparent that the diagnostic testis biopsy has been used to study the pathological basis of male infertility for 60 years.
[10] The Johnsen scoring system involves a quantitative assessment of individual germ cell types that is very detailed and relatively laborious for routine clinical use.
This was aptly demonstrated in a study by Cooperberg et al. in which the histology readings from two independent pathological reviews were prospectively compared with 113 testis biopsies undertaken for infertility.
Thus, although commonly used, the classical testis biopsy has little or no correlation with specific diseases, is associated with significant variability in interpretation, and can miss mixed patterns of spermatogenesis that may qualify infertile men for assisted reproduction.
In addition to accurately demonstrating the presence or absence of mature sperm with tails, FNA provides tubular cells for cytologic analysis, also informative for the diagnosis of infertility.
Despite this caveat, the correlation of FNA cytology to testis biopsy histology is very high (84–97%) in comparative studies comprising almost 400 patients (Table 1).
Similar to the issue with biopsy histology, although several excellent descriptions of testis seminiferous epithelium cytology have been reported, no individual classification method has been uniformly adopted by cytologists as a standard approach.
[12] Verma et al. also determined differential cell counts in patients with normal spermatogenesis; however, the reported ratios differed dramatically from those of Papic.
Thus, the determination of histology by FNA cytology pattern is accurate and suggests that the more invasive testis biopsy is unnecessary to diagnose states of infertility.
Similarly, FNA was applied systematically to detect the presence or absence of sperm in varied geographical areas of the testis.
These data confirmed intratesticular heterogeneity with respect to sperm distribution and suggested the potential of FNA to localize patches of active spermatogenesis in failing testes.
Suction is released, and then the tissue fragments are expelled onto a slide, gently smeared, and immediately fixed in 95% ethyl alcohol.
For immediate interpretation, fixed slides are stained with undiluted toluidine blue and read with brightfield microscopy after 15 seconds.
In another study, systematic testis FNA was used to determine which men were candidates for IVF-ICSI and to guide sperm retrieval procedures.
Thus, this study confirmed that FNA maps can accurately identify azoospermic patients who are candidates for sperm retrieval and ICSI.
For this indication, men have testis atrophy, an elevated serum follicle stimulating hormone (FSH) level, or a prior biopsy revealing abnormal or absent spermatogenesis.
From a comprehensive study of 118 consecutive azoospermic, infertile men who underwent FNA mapping, much has been learned about the geography of spermatogenesis in both normal (obstructed) and abnormal (nonobstructed) testes.
There was also an intratesticular (site-to-site within the same testis) variation in sperm presence in 25% of cases and an intertesticular (side-to-side in the same individual) discordance rate of 19%.
This suggests that bilateral examinations are crucial to fully informing men with nonobstructive azoospermia about opportunities for fatherhood,[21][22] FNA mapping has also been used to determine whether particular geographic sites are more likely to have sperm than others.
In addition, certain histologic patterns may reflect a more global testicular dysfunction due to underlying genetic causes, and thus a poorer likelihood of sperm identification.
