FNA mapping is an application of fine-needle aspiration (FNA) to the testis for the diagnosis of male infertility. FNA cytology has been used to examine pathological human tissue from various organs for over 100 years.Posner C. Die diagnostische Hodenpunktion. Berl Klin Wochenschr 1905;42b:1119-1121 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.Hendricks FB, Lambird PA, Murph GP. Percutaneous needle biopsy of the testis. Fertil Steril.1969; 20:478-81 Although recognized as a reliable, and informative technique,Gottschalk-Sabag S, Glick T, Weiss DB. Fine needle aspiration of the testis and correlation with testicular open biopsy. Acta Cytol 1993;37:67-72.Mallidis C, Gordon Baker HW. Fine needle tissue aspiration biopsy of the testis. Fertil Steril 1994;61:367-375. testis FNA has not been widely used in U.S. to evaluate male infertility. Recently, however, testicular FNA has gained popularity as both a diagnostic and therapeutic tool for the management of clinical male infertility for several reasons:
The testis is an ideal organ for evaluation by FNA because of its uniform cellularity and easy accessibility. The trend toward minimally invasive procedures and cost-containment views FNA favorably compared to surgical testis biopsy. The realization that the specific histologic abnormality observed on testis biopsy has no definite correlation to either the etiology of infertility or to the ability to find sperm for assisted reproduction. Assisted reproduction has undergone dramatic advances such that testis sperm are routinely used for biological pregnancies, thus fueling the development of novel FNA techniques to both locate and procure sperm.
For these reasons, there has been a resurgence of FNA as an important, minimally invasive tool for the evaluation and management of male infertility.
Changes to infertility medicine
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 field began in earnest in 1978 when the first successful in vitro fertilization (IVF) cycle was performed. This technique involves controlled ovarian stimulation followed by egg retrieval, in vitro fertilization, and embryo transfer to the uterus. In the United States, the number of babies born to infertile couples with IVF has risen logarithmically from 260 babies in 1985 to almost 50,000 in 2003. Another significant advance in ART was the development of intracytoplasmic sperm injection (ICSI) in 1992.Palermo G, Joris H, Devroey P et al. Pregnancies after intracytoplasmic injection of single spermatozoon into an oocyte. Lancet 1992; 340: 17. Performed in conjunction with IVF, ICSI involves the injection of a single, viable sperm directly into the egg cytoplasm in vitro to facilitate fertilization in cases of low sperm numbers. ICSI has decreased the numerical sperm requirement for egg fertilization with IVF from hundreds of thousands of sperm for each egg to a single sperm. In addition, ICSI allows sperm with limited intrinsic fertilizing capacity, including "immature" sperm obtained from the reproductive tract of men with no sperm in the ejaculate to reliably fertilize eggs. Indeed, ICSI has become so popular that U.S. clinics have routinely used it in more than 56% of their IVF cases.
The success of ICSI has also encouraged reproductive clinicians to look beyond the ejaculate and into the male reproductive tract to find sperm. Currently, sources of sperm routinely used for ICSI include sperm from the vas deferens, epididymis, and testicle. As ART has evolved, so too have novel FNA techniques to help diagnose and treat severe male infertility. An example of this is use of testicular FNA "mapping" to systemically assess and localize sperm for ART in men with azoospermia (no sperm count) and with testis failure characterized by "patchy" or "focal" spermatogenesis.Turek PJ, Ljung B-M, Cha I, Conaghan J. Diagnostic findings from testis fine needle aspiration mapping in obstructed and non-obstructed azoospermic men. J Urol 2000;163:1709-1716 Indeed, this combination of techniques has allowed men with even the severest forms of infertility, including men who are azoospermic after chemotherapy for cancer, to become fathers.Damani MN, Master V, Meng MV, Turek PJ, Oates RM. Post-chemotherapy ejaculatory azoospermia: Fatherhood with sperm from testis tissue using intracytoplasmic sperm injection. J Clin Oncology 2002; 20: 930-936.
Accuracy 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.Firket J and Damiean-Gillet M. Value and importance of testicular biopsies in Klinefelter's syndrome. Acta Clin Belg 1951; 6:80-1. The surgically obtained testis biopsy accurately describes testis architecture, is the best technique to detect in situ neoplasia or cancer, and allows for the overall assessment of the interstitium (Leydig cell number and hypertrophy). Levin described a qualitative method of assessing testis histologic patterns that is commonly used clinically to assess testis pathology in male infertility. Recognized patterns include: normal spermatogenesis, hypoplasia or hypospermatogenesis, complete or early maturation arrest, Sertoli cell-only or germ cell aplasia, incomplete or late maturation arrest, and sclerosis.Levin HS. Testicular biopsy in the study of male infertility: its current usefulness, histologic techniques, and prospects for the future. Hum Pathol 1979;10:569-84. Johnsen proposed a more quantitative analysis of testis cellular architecture based on the concept that testis damage causes a successive disappearance of the most mature germ cell type.Johnsen SG. Testicular biopsy score count--a method for registration of spermatogenesis in human testes: normal values and results in 335 hypogonadal males. Hormones 1970;1:2-25. The Johnsen scoring system involves a quantitative assessment of individual germ cell types that is very detailed and relatively laborious for routine clinical use.
Regardless of methodology, the analysis of testis biopsy histology lacks clinical value in cases of infertility because there is no clear correlation between histologic patterns or Johnsen score and the underlying etiology of infertility. That is to say, the clinical utility of understanding the histology pattern is low, because biopsy patterns do not correlate well with specific and correctable diseases. In addition, the interobserver variability in testis biopsy readings for infertility is significant. 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.Cooperberg MR, Chi T, Jad A, Cha I, and PJ Turek. Variation in testis biopsy interpretation: implications for male infertility care in the era of intracytoplasmic sperm injection. Fertil Steril 2005; 84: 672-7. Importantly, in 28% of cases preparation artifact or insufficient biopsy size rendered the sample suboptimal for interpretation. In addition, in 46% of cases, the two reviews disagreed, and this discordance resulted in significant changes in clinical care in 27% of cases. The most common error in pathological review was the under-appreciation of mixed histological patterns that are common and characteristic of infertile men with no sperm counts. 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.
FNA cytology vs testis biopsy
In many countries, testicular FNA cytology is preferable to surgical testis biopsy for the evaluation of male infertility. 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. Unlike testis biopsy histology, however, FNA cytology has not been rigorously evaluated for the ability to distinguish in situ neoplasia and testis cancer. 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).
+ Table 1. Literature that Correlates Testicular FNA Cytology to Biopsy Histology Study # Patients % Agreement Persson, 1971 42 86% Gottschalk-Sabag, 1993 47 87% Mallidis, 1994 46 94% Craft, 1997 19 84% Odabas, 1997 24 90% Mahajan, 1999 60 97% Rammou-Kinia, 1999 30 87% Meng, 2000 87 94% Qublan, 2002 34 96% Aridogan, 2003 40 90% Mehrotra, 2007 58 94% 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. Papic et al. quantified each cell type and calculated various cell indices and ratios and found that cytologic smears correlated well with histologic diagnoses.Papic Z, Katona G, Skrabalo Z: The cytologic identification and quantification of testicular cell subtypes. Acta Cytol 1988;32:697-706. Verma et al. also determined differential cell counts in patients with normal spermatogenesis; however, the reported ratios differed dramatically from those of Papic.Verma AK, Basu D, Jayaram G. Testicular cytology in azoospermia. Diag Cytopathol 1993;9:37-42. Batra et al. have also published a cytologic schema in which the spermatic index, Sertoli cell index, and sperm-Sertoli cell indices are categorized into various histologic groups.Batra VV, Khadgawat R, Agarwal A, Krishnani N, Mishra SK, Mithal A, Pandey R. Correlation of cell counts and indices in testicular FNAC with histology in male infertility. Acta Cytol 1999;43:617-623. Using this system, they reported that differences in cell counts and indices could predict histologic categories. Among the different classification systems for testis FNA, those that attempt to correlate cytologic findings with biopsy histology hold the most promise to replace histology.