Microscopic ferning in human pre-ejaculate is highly correlated with the absence of sperm.

Objective: We characterize microscopic ferning in pre-ejaculate samples with and without sperm.

Study Design: Healthy, male, withdrawal-experienced participants provided up to three paired pre-ejaculate and ejaculate samples. We centrifuged ejaculate samples to obtain a supernatant without sperm. After sperm analysis, we dried and evaluated pre-ejaculate, ejaculate, and supernatants for microscopic ferning.

Results: Of 57 pre-ejaculate samples (N = 24 men), seven (12.3%) contained sperm, none of which exhibited ferning. Sixty-six percent (33/50) of pre-ejaculate samples without sperm exhibited ferning. Neither ejaculate nor supernatant samples exhibited ferning.

Conclusion: Ferning may distinguish clinical pre-ejaculate with and without sperm. Ferning exhibited 100% specificity for pre-ejaculate without sperm.