Oligospermia / Asthenospermia / Teratospermia

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 14, 2026

OAT syndrome (oligoasthenoteratospermia) is a combined sperm parameter deficit defined by three simultaneous abnormalities: low sperm concentration (oligospermia), reduced progressive motility (asthenospermia), and abnormal morphology (teratospermia). Each parameter is measured against WHO 2021 reference values: concentration below 16 million per milliliter, progressive motility below 30%, and normal morphology below 4% by Kruger strict criteria.¹ When all three fall below threshold together, the combined deficiency is termed OAT syndrome.

The triad is not a disease in itself; it is a signal that underlying pathology is impairing spermatogenesis. Common drivers include varicocele, oxidative stress, hormonal insufficiency, genital tract infection, and genetic factors. Identifying the cause determines whether restoration is feasible. OAT syndrome that goes unexplored leaves correctable conditions untreated and couples without a meaningful path forward.

In the restorative approach to male factor infertility, OAT syndrome prompts a systematic evaluation of both partners rather than a direct referral for ICSI. Treating the underlying cause can improve parameters enough for natural conception. and restorative andrology.

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.