Table V.

Summary of generally accepted causal factors and additional potential contributing factors on severe male factor infertility ordered according to the severity of the effect on sperm parameters and fertility potential.

Classification	Subclass	Factora	Fertile men (%)	Infertile men (%)	Effect among infertility patients
Causal factors	Absolute	Secondary hypogonadism	0	1.3	100% aspermia, azoospermia or cryptozoospermia
		Seminal tract obstruction	0	5.9	99% aspermia, azoospermia or cryptozoospermia
		Known genetic causesb	0	7.8	87.4% aspermia, azoospermia or cryptozoospermia
	Severe	Oncological diseases	0.3	1.6	62.7% aspermia, azoospermia or cryptozoospermia 37.3% oligozoospermia
		Severe sexual dysfunction	0	4.4	55.3% aspermia, azoospermia or cryptozoospermia 44.7% oligozoospermia
	Plausible	Congenital anomalies in uro-genital tract	1.8	10.7	40.3% aspermia, azoospermia or cryptozoospermia 59.7% oligozoospermia
		Acquired or secondary testicular damage	1.2	6.6	21.9% aspermia, azoospermia or cryptozoospermia 78.1% oligozoospermia
Potential contributing factors	Testicular health	Varicocele, Grade 2-3	12.0	26	Increased prevalence in idiopathic infertility and ‘Other testicular factors’ groups. Increased prevalence among all patients with detectable (n > 0) sperm counts, i.e. except for aspermia and azoospermia.
		Leukocytospermia	7.4	13.5	Increased prevalence in idiopathic infertility and ‘Seminal tract obstruction’ groups. Increased prevalence only in oligozoospermia cases.
	General health	Chronic disease	9.8	24.4	Increased prevalence in idiopathic infertility, ‘Genetic causes’, ‘Congential anomalies in uro-genital tract’ and ‘Other testicular factors’ groups. Contribution to aspermia excluded.
		Overweight (Obesity)	48.6 (13.5)	60.4 (22.0)	Increased prevalence in idiopathic infertily and in the majority of the causal factor subgroups.

^aIncluded clinical diagnoses are detailed in Table II.

^bAutosomal and sex chromosomal abnormalities, Y-chromosomal micordeletions, CTFR gene mutations.