Sertoli cell-only pattern (SCO) does not always cause elevated FSH: impact on sperm retrieval results in non-obstructive azoospermia (NOA)

Abstract

OBJECTIVE: To evaluate predictors of sperm retrieval success by microdissection TESE (mTESE) in males with NOA of SCO histology. To delineate the relationships between FSH and testicular volume in this subgroup. DESIGN: Retrospective cohort. MATERIALS AND METHODS: Serum FSH was measured in 373 males with biopsy-documented SCO who underwent mTESE for sperm retrieval by a single urologist (PNS). Azoospermia was confirmed on the day of mTESE. mTESE was performed using an operative microscope with extensive search for sperm for ICSI. Pregnancy was defined as presence of fetal heart detected on ultrasound. The primary outcome was detection of sperm with mTESE. Multivariable logistic regression assessed the association between testis volume, log-transformed FSH and mTESE success with a significant p-value<0.05. From this model, associations were estimated for specific odds ratios for easier interpretation. RESULTS: mTESE was successful in 45.3% (169/373) of patients with SCO. Surprisingly, mTESE failed in men with lower FSH (P<0.001) and larger testis volume (P=0.03). By regression to adjust for FSH, the odds of retrieval is significantly lower for men with SCO who had larger testis volume >10cc as compared to smaller <10cc (OR 0.15, 95% CI 0.03 to 0.84, P=0.03). Interestingly, the ability of FSH to predict odds of retrieval depends on testis size. For testes<10cc, FSH does not affect odds of sperm retrieval (OR 1.21, 95% CI 0.72 to 2.03, P=0.47), whereas for testes >10cc, an increase in FSH actually favors success (OR 2.57 per unit increase in logFSH, 95% CI 1.41 to 4.65, P=0.002). Table 1 outlines increasing odds of success with different FSH cutoffs in the larger testis volume group. Of those with successful sperm retrieval, fertilization failed in 6.9% while pregnancy and miscarriage rates were 51% and 7.4%. CONCLUSIONS: Men with SCO may have normal FSH, which commonly occurs in men with larger testicular volume. mTESE success is lower for men with larger testes and normal FSH. This finding suggests that despite more Leydig and Sertoli cells maintaining endocrine feedback, spermatogenesis is commonly absent for SCO males with low FSH. However, it is reassuring that if sperm are found, pregnancy rates are not affected.Table 1Odds of sperm retrieval in men with larger testis volume (>10cc) as predicted by different FSH levelsFSH (IU/mL)OR (95% CI)P-value(Reference) 7.61.0101.3 (1.1-1.5)0.002151.9 (1.3-2.8)“202.5 (1.4-4.3)“303.6 (1.6-7.9)“404.7 (1.8-12.5)“ Open table in a new tab