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.