However, in cases with negative TESE only smoking was identified as a predictive factor for negative sperm retrieval and was established as a risk factor.<b>Abbreviations:</b> AZF: azoospermia factor; BMI: body mass index; Crypt: cryptozoospermia; FSH: Follicle-Stimulating Hormone; ICSI: intracytoplasmic sperm injection; IU: international unit; KS: Klinefelter syndrome; LH: Luteinizing Hormone; mL: milliliter; NOA: non-obstructive azoospermia; OA: obstructive azoospermia; T: testosterone; TESA: testicular sperm aspiration; TESE: testicular sperm extraction.
Aproximately 10% of patients with non-obstructive azoospermia and 5% with non-obstructive severe oligozoospermia carry AZF region microdeletions (AZoospermic Factor) in the Y chromosome.