It is time for a more standardized approach to identifying surgical outcome of non‐obstructive azoospermia

Non-obstructive azoospermia (NOA) is one of the most disastrous and frustrating disease conditions for the young infertile couples and doctors dealing with it. Except for special cases such as hypogonadotropic hypogonadism, most medical therapies for NOA are ineffective. Although many investigations such as spermatogonial stem cell transplantation for NOA are ongoing, they are still yet to be used for actual clinical application. Currently, the only proven treatment option for NOA which is not amenable to medical treatment is acquiring mature spermatozoa surgically and undergoing IVF/ICSI. There have been many surgical methods to retrieve mature spermatozoa in NOA with various outcomes. Recently, microsurgical approach has become a standard technique to maximize the sperm retrieval rate for NOA. Microsurgical-TESE (micro-TESE) was first reported by Schlegel, (1999). Using an operating microscope, it is expected that the surgeon is able to better visualize testicular regions containing spermatozoa by identifying differences in the size and opacity of seminiferous tubules. Since then, studies reported improved sperm retrieval rate compared with other previous surgical techniques such as TESA or conventional TESE. Recent studies reported approximately 30–70% of sperm retrieval rate with micro-TESE approach (Berookhim et al., 2014; Deruyver et al., 2014; Bernie et al., 2015). Unfortunately, many urologists performing micro-TESE often feel that there is a significant discrepancy between the real practice and the reported success rate in the articles. Supposedly, tubules with spermatozoa are expected to be larger, thicker, and more opaque under surgical microscopy during micro-TESE. However, in many NOA cases, such thicker tubules are not distinctive and operators are often confronted with rather homogenous seminiferous tubules. In such cases, if too much testicular parenchyma were taken out for extensive tissue collection, the potential risk of hypogonadism would increase. Besides, the relatively thicker tubules which are collected microsurgically often do not bear mature spermatozoa after being processed in the laboratory. Surgical technique for NOA should be developed continuously. Micro-TESE definitely has several advantages such as identifying dilated seminiferous tubules under higher magnification and minimizing surgical invasiveness. However, I am afraid that the current published data are relatively poorly analyzed in regard to micro-TESE outcome, therefore, may mislead many clinicians. Recently, Anderson & Hotaling (2015) also pointed out the limitations of the published data. They stressed the importance of implementation of standardized patient characteristics such as age, body mass index, follicle-stimulating hormone, longitudinal testis axis, testis volume, genetic abnormalities as well as tissue processing technique in dealing with surgical outcome of NOA. The author really agrees with Anderson and Hotaling. There is a chance that the published high sperm retrieval rate may be because of the heterogeneity of the included study group. NOA is not a single specific disease, in fact, it is a quite heterogeneous condition that includes all azoospermia that is not caused by obstructive lesion. Other factors such as racial difference or laboratory tissue processing also could contribute to different outcomes to some extent. Several suggestions to standardize the surgical sperm retrieval rate for NOA can be proposed. Firstly, we need more specific inclusion criteria of NOA for micro-TESE. Comparison of sperm retrieval rate only from NOA patients with elevated serum FSH could be one effective way to objectively compare the results. Secondly, micro-TESE data for cryptozoospermia may be excluded from the overall outcome data. Generally, higher chance of sperm retrieval can be expected because ongoing spermatogenesis has already been proven in these patients. Thirdly, it would be better to exclude azoospermia patients with normal FSH and normal testis size who did not undergo testis biopsy showing impaired spermatogenesis. If not, obstructive type azoospermia might be included in the study resulting in very high sperm retrieval rate. Data of life-threatening diseases such as malignancy are strictly classified according to many parameters including the