Luteinized Unruptured Follicle (LUF) Syndrome

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 7, 2026

A condition in which the dominant follicle reaches maturity and undergoes apparent luteinization (progesterone production begins) without actually releasing the egg (anovulation occurs despite apparent cycle regularity). LUF can cause unexplained infertility despite normal menstrual cycles and is identified by follicle tracking ultrasound showing a persistent follicle that fails to collapse at expected ovulation time.³

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