Testicular sperm extraction prediction for patients with nonobstructive azoospermia by Raman spectroscopy

To address the need for a noninvasive test to predict testicular sperm extraction (TESE) success for patients with nonobstructive azoospermia (NOA).

Retrospective case-control study.

A total of 20 men aged 29-50 years with NOA who underwent microdissection TESE (microTESE) procedure were divided into positive [TESE(+), N = 10] and negative [TESE(-), N = 10] categories based on the success of sperm retrieval. Seminal plasma samples were obtained before the surgery and used in the study after the microTESE outcome became known.

Raman spectral features of seminal plasma samples in 2,800-3,050 cm^-1 wavenumber range obtained with hollow-core microstructured optical fiber (HC-MOF); nuclear magnetic resonance spectral features; reactive oxygen species (ROS) level measured using enzyme-linked immunosorbent assay (ELISA).

Successive sperm extraction by the microTESE procedure.

Raman spectroscopy analysis enhanced by HC-MOF revealed characteristic spectral differences between TESE(+) and TESE(-) seminal plasma samples in 2,850, 2,875, and 2,920 cm^-1 bands related to C-H stretching vibrations, which may be associated with an elevated contribution from lipids in TESE(+) samples. The diagnostic model based on principal component analysis provided 79%/68% accuracy, 0.863/0.810 receiver operating characteristic area under curve, and 77%/66% specificity with 80%/71% sensitivity (13-19/5-12 diagnostic odds ratio) on the training/test set using 5-fold 10-iteration cross-validation. The statistical significance of higher ROS levels in TESE(-) samples was not enough for robust prediction of successful TESE.

The HC-MOF-enhanced Raman spectroscopy is a rapid, noninvasive, cost-efficient, and easy-to-use method, which can be applied to predict TESE success in men with NOA, revealing differences in biochemical profiles of seminal plasma. Although validation on a bigger cohort is needed, this proof-of-concept study highlights perspectives of the technique for its widespread use in presurgical screening, preventing the risky invasive procedure in the case of low sperm extraction chance.