Differences and similarities between extremely severe oligozoospermia and cryptozoospermia in intracytoplasmic sperm injection

Patients with extremely severe oligozoospermia (ESO) and cryptozoospermia (CO) are suitable using intracytoplasmic sperm injection (ICSI) as an infertility treatment. However, some andrologists are confused to distinguish ESO and CO in clinic diagnose. This study was designed for the first time to evaluate and compare patients with ESO and CO to determine whether these are useful clinical distinctions. A total of 270 infertile men in our center were classified into four groups as Group nonobstruction azoospermia (NOA, n = 44), Group ESO (n = 78), Group CO (n = 40), and Group obstruction azoospermia (OA, n = 108). Comparisons of the volume of bilateral testes, the level of follicle stimulating hormone (FSH) and inhibin B were obtained in four groups. Then comparisons of fertilization rates, cleavage rate, and excellent embryos rate were obtained when couples performed ICSI. All indexes (volume of bilateral testis, level of FSH and inhibin B) in Groups ESO and CO were no difference, while Groups OA versus NOA, OA versus ESO, and OA versus CO were significant differences (P < 0.05). The rates of fertilization were no differences in Groups ESO and CO while Groups OA versus ESO, OA versus CO were significant differences (P < 0.05). Therefore, the spermatogenic functions in patients with CO and ESO were similar, better than NOA but worse than OA. However, it would be helpful to evaluate their spermatogenesis using testicular biopsies, especially accompanied azoospermia in clinical practice.