Correlation between testicular sperm extraction outcomes and clinical, endocrine and testicular histology parameters in 120 azoospermic men with normal serum FSH levels

We retrospectively evaluated the clinical and hormonal profiles, sperm extraction outcomes and testicular histology parameters in 120 azoospermic men with normal serum follicle-stimulating hormone (FSH) level. Microsurgical epididymal sperm aspiration (MESA) and testicular sperm extraction (TESE) were performed in 33 and 87 cases, respectively. Sperm were successfully retrieved in all the MESA procedures and in 65 of the TESE procedures. The mean serum FSH and inhibin B levels and the testicular volume differed significantly according to whether or not sperm were retrieved. The threshold serum inhibin B value for predicting successful TESE was 123.5 pg/mL (sensitivity: 69.7%; specificity: 66.7%). The 13 patients with Sertoli cell only syndrome (SCOS) had a higher mean serum FSH level and a lower mean serum inhibin B level than the other phenotypes. TESE was negative for 11 of the 13 SCOS men. The mean +/- SD inhibin B level was significantly lower in patients with 5-10 IU/L of FSH than those with 2-5 IU/L of FSH (108.30 +/- 53.86 vs. 175.23 +/- 70.17 pg/mL, respectively). The sperm retrieval rates were 71.42% for the group with 5-10 IU/L of FSH and 87.32% for the group with 2-5 IU/L of FSH. Ten of the 13 SCOS men had a FSH level between 5 and 10 IU/L. The clinical pregnancy rate was significantly lower (p = 0.04) in the group with 5-10 IU/L (50%) of FSH than in the group with 2-5 IU/L (77.5%) of FSH. In conclusion, there is no FSH value below which spermatogenesis is always found. Inhibin B assays and clinical assessments are thus of particular value in men with normal serum FSH levels.