Clinical experience with azoospermia: aetiology and chances for spermatozoa detection upon biopsy

The clinical workup of the infertile male with azoospermia aims at determining the aetiology and estimating the chances of finding spermatozoa by testicular sperm extraction (TESE). To establish prognostic criteria, 1583 consecutive patients with azoospermia consulting the Centre of Reproductive Medicine and Andrology, Münster, a tertiary referral centre, between 1976 and 2009 comprising 9.8% of all patients providing a semen sample were included in this retrospective analysis. The frequencies of diagnoses were as follows: 21% genetic causes (14% Klinefelter syndrome, 1% other chromosomal aberrations, 2% Y-chromosomal microdeletions, 1% hypogonadotropic hypogonadism, 3% congenital bilateral absence of the vas deferens), 31% current or former maldescended testes, varicocele, urogenital infections, 15% malignancies, 11% obstructions, 7% endocrine or other chronic diseases and 12% idiopathic azoospermia. Receiver-operating characteristic curves for chances of finding spermatozoa by testicular biopsy were calculated for testicular volume, serum follicle-stimulating hormone (FSH) and the seminal markers α-glucosidase, fructose and zinc where these data were available (N=283). Histograms of the seminal markers comparing data from men with obstructive azoospermia and normozoospermia visualize their discriminating power. Evidence-based threshold values for high chances of positive testicular biopsy serving as surrogate marker for TESE were derived from the subgroup of men with obstructive azoospermia for testicular volume (≥21mL), FSH (≤10U/L) and seminal α-glucosidase (≤18mU/ejaculate). Fructose and zinc could not predict the chances of finding spermatozoa upon biopsy. Based on these three parameters, positive biopsy and presumably TESE success can be quickly and reliably estimated in everyday practice with the colour-coded figures constructed from these data. As a seminal α-glucosidase reference limit of 18mU/ejaculate can also be used to diagnose congenital bilateral absence of the vas deferens, α-glucosidase (rather than seminal fructose) should be determined as part of the clinical routine when counselling patients before testicular biopsy.