Sperm retrieval predictive factors and testicular histology in nonobstructive azoospermia patients

Ming-Wei Li; I-Ni Chiang; Yi-Kai Chang; Shuo-Meng Wang; Hong-Chiang Chang

doi:10.4103/UROS.UROS_75_19

ORIGINAL ARTICLE

Year : 2020 | Volume : 31 | Issue : 2 | Page : 51-55

Sperm retrieval predictive factors and testicular histology in nonobstructive azoospermia patients

Ming-Wei Li, I-Ni Chiang, Yi-Kai Chang, Shuo-Meng Wang, Hong-Chiang Chang
Department of Urology, National Taiwan University Hospital, Taipei, Taiwan

Date of Submission	07-Oct-2019
Date of Decision	19-Jan-2020
Date of Acceptance	27-Feb-2020
Date of Web Publication	25-Apr-2020

Correspondence Address:
Hong-Chiang Chang
Department of Urology, National Taiwan University Hospital, No. 7, Chung Shan S. Road, Taipei City 10002
Taiwan

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/UROS.UROS_75_19

Abstract

Purpose: The purpose of this study was to investigate the potential factors for sperm retrieval prediction. Materials and Methods: This is a retrospective and single-operator study at National Taiwan University Hospital. Between January 2009 and December 2017, 66 nonobstructive azoospermia (NOA) patients were collected. They received testicular biopsy and sperm retrieval including microsurgical epididymal sperm aspiration or microdissection testicular sperm extraction. Results: Eleven patients had normal spermatogenesis, with successful sperm retrieval (SSR) 90.9%; 21 patients hypospermatogenesis, with SSR 47.6%; 13 patients maturation arrest, with SSR 30.8%; and 21 patients Sertoli cell-only syndrome, with SSR 0%. SSR declined significantly when follicle-stimulating hormone (FSH) values rise: FSH <10 mIU/ml with SSR 59.1%, FSH 10–20 mIU/ml with SSR 26.3%, and FSH >20 mIU/ml with SSR 6.7% (P = 0.003). Receiver operating characteristic curve to predict SSR by FSH achieved the area under the curve 0.792, with the best cutoff point of FSH being at 6.8 mIU/ml. Conclusion: We concluded that a higher sperm retrieval rate was statistically significantly related to lower FSH, lower luteinizing hormone, and better histology types among the NOA men. In the absence of testicular histopathology before surgery, preoperative FSH can be used for prediction and counseling. FSH ≤6.8 mIU/ml predicts SSR with a sensitivity of 63.2% and specificity of 88.2%.

Keywords: Nonobstructive azoospermia, sperm retrieval, testicular histology

How to cite this article:
Li MW, Chiang IN, Chang YK, Wang SM, Chang HC. Sperm retrieval predictive factors and testicular histology in nonobstructive azoospermia patients. Urol Sci 2020;31:51-5

How to cite this URL:
Li MW, Chiang IN, Chang YK, Wang SM, Chang HC. Sperm retrieval predictive factors and testicular histology in nonobstructive azoospermia patients. Urol Sci [serial online] 2020 [cited 2021 Mar 8];31:51-5. Available from: https://www.e-urol-sci.com/text.asp?2020/31/2/51/283253

Introduction

Azoospermia is defined as the complete absence of sperm from the ejaculate and is identified in approximately 1% of all men and in 10%–15% of infertile males.^[1] At least two semen samples should be obtained ≥2 weeks apart and performed according to the World Health Organization guidelines.^[2] Azoospermia can be categorized into obstructive or nonobstructive. Hormone profiles and testicular size have been used to predict the cause of azoospermia.^[3],[4] A follicle-stimulating hormone (FSH) value higher than 7.6 mIU/ml and/or a testis long axis shorter than 4.6 cm are prediction factors for nonobstructive azoospermia (NOA).^[5]

Owing to the assisted reproductive technology, men with azoospermia can be treated through the use of sperm retrieval techniques in combination with in vitro fertilization (IVF).^[6],[7] Retrieved sperm may be used immediately in IVF or cryopreserved for future IVF. Sperm can be retrieved from a nonobstructive azoospermic epididymis or testis. It is known that the successful rate of sperm retrieval is dependent on the histology pattern.^[8],[9] Therefore, percutaneous or open testicular biopsy before sperm retrieval in azoospermic males has been used to predict successful rate.^[9] However, preoperative testicular biopsy was not performed in our hospital because biopsy is an invasive procedure which may cause damage to the testis. The predictive value of other noninvasive approaches varied between studies.^{[3],[4],[9],[10],[11],[12]}

This study was conducted to investigate the potential factors which would predict spermatogenesis in the patients with NOA. We analyzed hormone level, testicular histology, and sperm retrieval rate. The advantage of this study was that all cases received testicular biopsy for histopathology.

Materials and Methods

This is a retrospective and single-operator study at National Taiwan University Hospital. From January 2009 to December 2017, we collected 66 cases who were diagnosed with NOA clinically, according to history, physical examination, semen analysis, and hormone levels (FSH, luteinizing hormone [LH], and testosterone). Karyotype disorders were excluded. Other genetic testing was not conducted routinely. They received testicular biopsy and sperm retrieval including microsurgical epididymal sperm aspiration (MESA) or microdissection testicular sperm extraction (mTESE). Patients with previous prostatitis, epididymitis, orchitis, spinal cord injury, or known obstructive factors were excluded. This study is approved by National Taiwan University Hospital Research Ethics Committee (approval no. 201909070RINC obtained on Oct. 17^th 2019) and the informed consent was waived by IRB.

We reviewed the histological findings and analyzed the associated factors according to histology stratifications (normal spermatogenesis, hypospermatogenesis, maturation arrest, and Sertoli cell-only syndrome). Hypospermatogenesis was defined as the presentation of all stages of spermatogenesis present but reduced to a varying degree. Maturation arrest was defined as germ cell maturity cessation at a specific point. Sertoli cell-only syndrome was defined as a complete loss of the germinal epithelium in testicular tubule.

We explored the significant factors, including hormone profiles and histology findings, which impact the spermatogenesis. The data were analyzed with statistics of the Chi-square test, Fisher's exact test, Mann–Whitney U-test, and Kruskal–Wallis test.

Surgical procedures

MESA is the first choice among all sperm retrieval techniques.^[13] During MESA, sperm-containing epididymal fluid is aspirated from optimal areas of the epididymis that are selected and sampled using high-power optical magnification provided by a microscope.^[14] The specimen was checked with microscope immediately. If MESA failed to retrieve sperm, mTESE was performed as the second step.^[15],[16] At least three incisions were made if no sperm was found. Moreover, testicular biopsy was performed and sent for pathology for definite diagnosis.

Results

Sixty-six patients with NOA were enrolled (mean age: 35.6; standard deviation: 6.8; range: 22–54). The baseline characteristics of total patients are demonstrated in [Table 1]: mean body mass index (BMI) was 26.1, smoking rate – 36.2%, mean testicular size – 11.0 ml, mean FSH – 15.1 mIU/ml, mean LH – 6.7 mIU/ml, mean testosterone level – 3.5 ng/dl, varicocele > Grade II – 17.0%, and sperm retrieval rate – 36.4%. Fifteen patients had successful sperm retrieval (SSR) by MESA and nine patients by mTESE; both methods failed in 42 patients.

Table 1: Comparison of baseline factors and sperm retrieval rate in two histopathology groups

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Eleven patients had normal spermatogenesis and SSR 90.9%; 21 patients hypospermatogenesis, with SSR 47.6%; 13 patients maturation arrest, with SSR 30.8%; and 21 patients Sertoli cell-only syndrome, with SSR 0%. No sperm was retrieved in histology group with Sertoli cell-only syndrome. The patients with normal spermatogenesis and those with hypospermatogenesis were defined as Group 1. The patients with maturation arrest and those with Sertoli cell-only syndrome were defined as Group 2. We combined four histopathology patterns into two groups due to our small sample size. Clinical characteristics were compared between Groups 1 and 2 in [Table 1]. Significant differences (P < 0.05) were found in age (P = 0.036), FSH (P = 0.013), LH (P = 0.008), and SSR (P < 0.001).

A bar chart of FSH ranges and SSR is demonstrated in [Figure 1]. The sperm retrieval rate declined significantly when FSH elevated: FSH <10 mIU/ml had SSR 59.1%; FSH 10–20 mIU/ml had SSR 26.3%; and FSH >20 mIU/ml had SSR 6.7% (P < 0.05). The mean FSH of the patients with SSR was 19.2 mIU/ml while that of negative retrieval was 8.2 mIU/ml.

Figure 1: Successful sperm retrieval rate stratified by follicle-stimulating hormone. The retrieval rate declined significantly when follicle-stimulating hormone elevated

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The baseline characteristics stratified with serum FSH level are demonstrated in [Table 2], divided into three groups: FSH <10 mIU/ml, FSH 10–20 mIU/ml, and FSH >20 mIU/ml. There was no significant difference in age, BMI, testosterone, prolactin, smoking rate, and varicocele rate.

Table 2: Baseline characteristics stratified with follicle-stimulating hormone

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Smaller testicular size was noted with higher FSH level significantly (P = 0.002). The mean testicular size was 9.5 ml in FSH >20 mIU/ml, 11.2 ml in FSH 10–20 mIU/ml, and 13.4 ml in FSH <10 mIU/ml. Higher LH level was also noted with higher FSH level (P < 0.001). The mean LH level was 8.9 mIU/ml in FSH >20 mIU/ml, 6.6 mIU in FSH 10–20 mIU/ml, and 5.6 mIU in FSH <10 mIU/ml.

The correlation between preoperative clinical factors and SSR is calculated in [Table 3]. Lower FSH (P < 0.001), lower LH (P = 0.001), and older age (P = 0.02) were positively related to SSR. Testicular size, smoking, varicocele, and testosterone were not related.

Table 3: Characteristics of successful and failed sperm retrieval

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Since higher FSH was related to lower SSR, receiver operating characteristic (ROC) curve was made to evaluate the predictive value of FSH in [Figure 2]. The area under the curve (AUC) of FSH was 0.792, slightly higher than LH of 0.776. Both showed acceptable discrimination. According to the Youden's index, the best cutoff value was FSH ≤6.8 mIU/ml, with a sensitivity of 63.2% and specificity of 88.2%. For LH, the best cutoff value was ≤5.6 mIU/ml, with a sensitivity of 78.9% and specificity of 67.6%.

Figure 2: Receiver operating characteristic curve to predict sperm retrieval rate. The area under the curve of follicle-stimulating hormone was 0.792, slightly higher than luteinizing hormone of 0.776. The best cutoff value was follicle-stimulating hormone ≤6.8 mIU/ml, with a sensitivity of 63.2% and specificity of 88.2%

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There were seven patients who had sperm retrieved by MESA. Among these seven patients, the histopathology of testicular biopsy revealed two normal spermatogeneses, four hypospermatogeneses, and one maturation arrest. Five patients had smaller testicular size (>12 ml). The other two patients, who had normal size testes and no enlargement of the epididymis, were the only two presenting with normal spermatogenesis. One patient out of the seven had an elevated FSH of 15.7 mIU/ml. The other six patients had a mean FSH of 4.3 mIU/ml.

Discussion

Although final testicular histology was highly related to SSR, we could only access the histology through biopsy before sperm retrieval surgery.^[17] Ramasamy and Schlegel^[17] concluded that a limited number of testicular biopsies provide limited or no prognostic value for sperm retrieval. Biopsy may not describe the entire histology of testis. Therefore, FSH was a surrogate marker and less invasive test for SSR prediction.

The retrieval rate declined significantly when FSH elevated. FSH was divided into three groups at an interval of 10 mIU/ml (<10, 10–20, and >20). Between the three FSH groups, there was no significant difference in age, BMI, testosterone, prolactin, smoking rate, and varicocele rate. There was a trend that BMI rises as FSH elevated. A meta-analysis^[18] demonstrated equivocal relations between BMI and FSH, while BMI had a negative relationship with testosterone. Another meta-analysis^[19] demonstrated that being overweight and obesity were associated with an increased prevalence of azoospermia or oligospermia. The small sample size of the case series might explain the insignificant results of the study.

The histology of seminiferous tubules revealed whether germ cells were present and the degree of spermatogenesis. The advancement of histology correlated to successful retrieval rate significantly: normal spermatogenesis with SSR 90.9%, hypospermatogenesis 47.6%, maturation arrest 30.8%, and Sertoli cell-only syndrome 0%. Similar results were obtained in previous studies.^[8],[20] Some studies^[8],[20] revealed SSR in Sertoli cell-only syndrome 16.3%–30.5%, but, in our series, sperm recovery was not successful in patients with Sertoli cell-only syndrome. Sertoli cell-only syndrome was defined as lacking germ cells entirely, and sperm should not exist. This could be explained by the following reasons. First, it is known that histology pattern is focal in testes. In our hospital, the pathology report revealed the most advanced stage of spermatogenesis rather than the most common pattern. Second, at least three incisions at tunica albuginea were made in our TESE procedure. Therefore, a higher accuracy of histology report may be achieved.

As mentioned in our surgical technique, if MESA failed to retrieve sperm, mTESE was performed as the second step. Among seven patients having sperm retrieved by MESA, the histopathology of testicular biopsy revealed two normal spermatogeneses, four hypospermatogeneses, and one maturation arrest. It was difficult to establish the diagnosis between obstructive azoospermia (OA) and NOA in these patients when taking their low FSH and small testicular size into account. We assumed that mixed nonobstructive and obstructive factors might both coexist in these patients. This concept may also explain why there were 11 patients with normal spermatogenesis in our case series.

ROC curve to predict SSR by FSH achieved AUC 0.792, with the best cutoff point of FSH being 6.8 mIU/ml. The cutoff point was similar to a previous Western study,^[5] which included both OA and NOA. Our study demonstrated the counseling value of FSH in Taiwanese NOA.

The effects of male age on fertility are not fully elucidated. Advancing male age appears to affect semen quality and might lead to infertility or delayed conception.^[21] A study demonstrated a significant decrease in the incidence of normal sperm with increasing age.^[22] In our study, increasing age was significantly related to the advanced stage of spermatogenesis (P = 0.036) and SSR (P = 0.02), which was incompatible with the previous study. It could be explained that various factors beyond our collected data may influence male fertility, such as ejection frequency, history of chronic illness, and exposure to environmental toxins. Further investigation was needed to clarify this discrepancy.

Cissen et al.^[23] described a mathematical formulation for predicting the probability of sperm retrieval as follows: probability = 1/(1 + exp [−β]), where β = −1.009+ (male age × 0.058) + (LH × −0.115) + (LH2 × 0.001) + (FSH − 0.019) + (testosterone × 0.034) + (AZFc deletion − 1.480) + (idiopathic NOA − 0.855). The AUC of this formula was 0.62 lower than 0.792 predicted by FSH alone in our case series. However, patient groups were not comparable according to the different inclusion criteria. Both studies may need further external validations.

The limitations of our study included small patient number and lack of complete genetic profiles. Therefore, some specific genetic diseases were not labeled. In the future, we may explore factors and testicular histology of each genetic disease, if larger cohort was achieved.

Conclusion

Higher sperm retrieval rate was statistically significantly related to lower FSH, lower LH, and better histology types among the NOA men. However, testicular size and testosterone did not contribute significantly. In the absence of testicular histopathology before surgery, preoperative FSH can be used for prediction and counseling. FSH ≤6.8 mIU/ml predicts SSR with a sensitivity of 63.2% and specificity of 88.2%. No sperm was retrieved in the histology group with Sertoli cell-only syndrome, but this result might not be adapted to preoperative percutaneous testicular biopsy because of the focal pattern in testes.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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